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Lake Assal: nothing cool, but still cool (3/3)

Interpretation of the logger’s graph (using LogTag Analyzer 3 software)

The temperature curve of the 6 days/ 5 nights research period. The device was registering a value every 2 minutes (zoom in for better view)

First day (June 21st)

It is the single day when I’ve spent significant time nearby the measuring equipment in the wadi. It was haze during my hike through the salt flats of Lake Assal before entering the gorge, with little wind. The logger started to record at 10:43 AM and the first reading can be considered legit as I waited sufficient time with the sensor placed under the helical shield to accomodate the ambience before pushing the start button. As I set the device for 2 minutes logging (short intervals) the curve has the typical “saw aspect” with many small ups and downs inside the general “big waves”. The temperature was rising more abruptly until 2:17 PM when reached 47.0 C, after which slowly increased until 3:59 PM when recorded the day’s maximum temperature of 47.4 degrees Celsius (quite normal evolution). During this time the sky was clear or partially covered, but the north-western clouds never managed to block the sun.

I left the area after 5:18 PM, when the temperature was already descending and the sun was reached by the clouds just a little before disappearing behind the walls of the valley. After spending some time outside the gorge where encountering a sandstorm after 6 PM I later returned to the tripod to see if it survived the strong wind (luckily yes). This interval coincides with a more abrupt drop of 2.3 degrees between 6:09 and 6:25 PM (from 46.3 to 44.0 C), following a more constant period even if the sun was already gone for almost an hour.

The temperature curve of the first day and the following night

After this the descend is more natural until 2:57 AM when it reached 39.4 C, the lowest temperature of the night. Before 5 AM it was a strange rise from the already very high base to 40.9 C, then started to drop again. The lowest reading of 38.1 C happened shortly before 8 AM in full daylight, but the sun probably reach inside the gorge only later. I’ve spent this night around the lake and measured similar temperatures with my handheld device (38-40 C between 0 – 6 AM). Meanwhile the sky became cloudier.

Second day (June 22nd)

I left the area during this morning and returned only in the last day (26th in the late afternoon) to collect the equipment. This second day is a weird one as it is composed of the lowest maximum (44.3 C at 3:15 PM) sandwiched between the two highest minimums (38.1 and 37.6 C).

The temperature curve of the second day and the following night

This and the fact that it has some shorter abrupt drops in the early evening (again between 6 – 7 PM) suggests that it was windy, another sandstorm is very likely. However the mentioned max and the min were both registered in the expected period (afternoon, respectively early morning).

Third day (June 23rd)

During this day I was on a trip around the western part of the Ghoubbet bay, so not too far from Lake Assal (25 km from the gorge). The morning was cloudier, while the midday and early afternoon sunny and very hot. I measured 46 degrees on the black lava field with my handheld thermometer, while the wind was moderately blowing.

The temperature curve of the third day and the following night

From the morning there was a constant rise until 3:03 PM when the day’s maximum of 47.2 C was registered and the same value was reached again at 4:25 PM after a small setback. This second peak was instantly followed by a big drop of more than 3 degrees in 6 minutes, then the curve became more normal. This coincides with the time when I was finishing my hike and saw some bigger clouds forming in the north-west. Probably it was again only wind, without rain. We can also observe on this day an unnatural 3 degree warming in the evening between 9 – 10 PM (exceeding 40 degrees again), certainly khamsin. The descend happened only after midnight, while the minimum was 35.2 C in the early morning.

Fourth day (June 24th)

This day the temperature has a quite normal evolution, reaching 44.6 C at 3:07 PM following a constant rise, while after 4 PM starts the descend, which has no abrupt changes (except a slight rise in the evening) until 5:05 AM, when recording the minimum of 33.3 C. This will be also the lowest temperature of the entire measuring period.

The temperature curve of the fourth day and the following night

I was in Djibouti city on this day, so I don’t have direct info about the cloud cover over the area.

Fifth day (June 25th)

On this day I was again on a trip to Ghoubbet bay, this time in the south-eastern part, thus a little farther from my study area (around 45 km). It was less haze than on the other days, from the high ledge of the plateau I could see the other side of the bay (though only barely).

The temperature curve of the fifth day and the following night

This day the max was reached a little earlier than usually: 44.5 C at 2:29 PM, with a slight setback (almost constancy) afterwards, the concrete drop starting only after 5 PM with some abrupt changes in the first half hour. It was again a +2 degree rise in the evening, followed by a less constant decrease until dawn, when the minimum of 35.8 C happened.

Sixth, last day (June 26th)

Today in the late afternoon I came back to Lake Assal to collect the equipment. It was haze again with a few clouds in the sky (not clearly seen). The timing was good as I reached the gorge only after 6 PM when the temperature was already decreasing, thus having the daily maximum recorded also for this day.

The temperature curve of the sixth (last) day

The peak of 46.1 C was reached at 3:59 PM, exactly in the same minute when the first day’s 47.4 C happened. We can observe on the graph an abrupt early morning rise of 1.6 degrees, respectively a +2 degree unnatural drop after 1 PM. The rest is more or less a constant rise until 4 PM, then decreasing. The last reading was 43.6 C at 6:07 PM when the logger was stopped.

The mean temperature of the 6 days/ 5 nights measuring period in the wadi is a round 40.0 degrees Celsius, an unusually high average for sure. The mean maximum was 45.7 degrees, while the mean minimum, 36.0 degrees. The maximum is similar to the ones measured at the hottest weather stations in the world: Death Valley (Furnace Creek), Persian Gulf states (Ahvaz, Basrah, Jahra), central-western Sahara (In Salah, Reggane), Pakistan (Sibi, Jacobabad) and the Ethiopian Danakil (Dallol). The minimums seems to be higher than anywhere else on the planet, no station recording above 35 C average lows in any month.

General conclusions

  • Lake Assal area is one of the hottest places on the Planet, having a similar climate with the Ethiopian Danakil, where the highest yearly average of 34.6 C was recorded between 1960-1966 at Dallol.
  • The daily maximums are usually happening in the afternoon around 3-4 PM, after a more or less constant rise from the morning.
  • The late afternoon/ evening hours are characterised by instability and more abrupt changes, the wind velocity being the highest in this period.
  • Temperature rise of 2-3 degrees can happen at any time during the dark hours, exceeding 40 C even at dawn.
  • The daily amplitude is small, especially for a tropical desert. This is caused mostly by the hot and dry khamsin wind, which mixes the layers. Clouds can keep the heated air under their blanket during night, enhancing this phenomenon.
  • There are more clouds in the night and morning than at midday.
The satellite images of Djibouti taken on June 21st (left) with khamsin effect vs June 11th (right) with normal sky

Comparison with Djibouti (Ambouli International Airport) weather station

According to Wunderground’s history, but also mentioned by my driver Houmed, the temperature in Djibouti city reached 45 degrees Celsius on 21st June (2-3 PM), when the 47.4 C peak was recorded in the gorge near Lake Assal. This is only one degree shy of the city’s absolute record and certainly was caused by the khamsin. As Ambouli’s available values are all rounded I must work with these: in 21st the difference is 2.4 degrees in favour of Lake Assal.

The temperature curve of Djibouti weather station on June 21st (Wunderground/ History)

Also 22nd was a very hot day in the capital, when 44 C was measured in the same early afternoon interval. As I spent this day in the city, I can confirm from personal experience that the heat was extreme indeed. More than that, this day the two peaks were very similar, my logger measuring its lowest maximum in the gorge: 44.3 C

On 23rd the difference is bigger, the city recording 42 degrees, while Lake Assal 47.2 C: 5.2 degrees. June 24th was the “mildest” day in the capital with only 37 degrees (but likely with high humidity), while my station recorded 44.6 C: 7.6 degrees difference, the biggest one. On 25th the discrepancy is smaller again, Djibouti reaching 41, while Lake Assal 44.5 C: 3.5 degrees. In the last day, on 26th, the disparity is again high: 39 vs 46.1 C: 7.1 degrees.

The average difference between the maximums for the six days is 4.3 degrees in favor of Lake Assal. Due to the coastal placement Djibouti is usually more humid with a high heat index even with only 35-36 degrees Celsius, while Lake Assal is much more affected by the dry wind.

Comparison with Dallol (Ethiopian Danakil)

As Dallol weather station operated only between 1960-1966 and the datas are also kind of questionable, this comparison will be less concludent.

Weather statistics for Dallol (Wikipedia)

If we take into consideration the month of June, Dallol’s mean maximum is one degree higher than the average max of my six day research near Lake Assal: 45.7 degrees. However, I have some doubts regarding Dallol’s value, which compared to its absolute June max looks unusually high: only 1-1.5 degrees difference between them. That’s just too small even for 6-7 years of measurement. As I saw a lot of suspicious climate charts and tables in my life with significant differences even between the same locations, my general opinion is that many of them is based on algorythms and are not coming from real, ground based measurements.

Final question: Could Lake Assal’s depression beat the actual World Record for the highest temperature? We could not exclude this, but my opinion is that the upper limit must be somewhere between 50-52 degrees Celsius here. I think there are more chances to beat the highest low temperature for one night, the actual record being 44.2 degrees Celsius in Khasab (Oman).

I consider this research a successful one, actually it’s the first one flawlessly completed with all days and nights correctly monitored.

Lake Assal: nothing cool, but still cool (2/3)

Journey photo album

First day in Djibouti: befriending the local climate

Mosque in the center area

On the way to Arhiba square to see from where are the Tadjoura minibuses depart. The air is hot and humid with very high heat index

It seems that Menelik hotel, the iconic building of the old colonial center was recently renovated

My hotel room at “City Guest by Citylife” with the mandatory air conditioning in this climate

Palace Kempinski, the most luxurious hotel in Djibouti seen from Heron Beach

The coastal breeze is great for kiteboarding

In the early morning of June 21st (which btw is my 44th birthday) we started the journey to Lake Assal. Here we are on the Ethiopian main road with heavy truck traffic near We’a settlement

Hard life on the side of the road

We left the main road and continued on the Tadjoura way

Canyon d’Adaile, known to the local afar people as Dimbia is one of the places along the road where all tourists stop

The other is less well defined, but can happen at any time while crossing the barren plateau: hamadryas baboons

They are used with people and represent no danger, just curious and looking for food

Wind turbines near Ghoubbet bay with Ile du Diable (Devil’s Island) on the background. It’s heavy haze today, which means the hot and dry Khamsin wind is active

Near Karta village

Descending the plateau towards Lake Assal

We are lucky to see a “salt caravan”, which is carrying the manually collected salt from the lake. Afars do this even in the relentless summer, hard to belive!

Now we are well below sea level, the bottom of Africa (-155 m) is close. I can see the salt factory on the shore

The hot spring near the lake is another touristic attraction where every driver stops. It’s only around 8 AM and already very hot outside, hard to tell how much is caused by the air and how much because of the water

The classical view of Lac Assal shortly before the end of the asphalt road

My driver asking the local guy if there is a chance for me to found a truck tomorrow from here to the Tadjoura road. The answer is not very positive, it seems that now the traffic is restrained (could be seasonal), also tourists are much less in the off-season. We’ll see

With a 20 kg backpack from which half is water, around 8:15 AM I started the hike towards my target. There are a few tracks on the salt pan used mostly by the salt worker trucks, one even appear (!) on some maps as a “national highway” 🙂

The surface is pretty solid in the first part

As I am approaching the foothills became a little grainier…

…then changes to the characteristic polygonal crusty aspect

Even farther there was dark mud, fortunately enough solid for walking. Certainly not the same thing for cars…

Yeah, definitely more moisture in the ground, the small pond must have similar composition as the big lake

I was a little surprised to see them here, it’s no more than 1 km to the target

The last part is on sandy-gravel surface, I am approaching the gorge

And here we are: the place looks good for my purpose also in reality. The heat is oppressive after carrying the heavy luggage for two hours, but I dont’s waste the time, only drink some water and start the preparations
The mini weather station is soon rised on the wadi’s floor and after leaving the sensor under the Barani shield at least 15 minutes to accomodate to the ambience, at 10:43 AM the logger started its operation
First reading: 42.4 degrees, a decent start
General view of the measuring spot on the lower “course” of Kadda Galeita
The legs of the tripod were secured with rocks to can handle the wind
I found a shelter under an overhang of the gorge’s southern wall, which seems to be the single proper one in the surroundings. Divine providence, definitely
Even in the shade it’s insanely hot
“The Black Midget”, my shadow around noon on the tropics
1 PM: the temperature is rising
At this period the ground must be the hottest. I check it on the sandy surface, which is the best for the highest readings
2 PM: went over 46 degrees, I am content
Around 3 PM have reached 47 degrees, the atmosphere is hellish
Good to have this shelter, the sun is extremely punishing
I used the umbrella as an auxiliary to block the heavy afternoon rays
It’s almost unbelievable how in complete shadow the hot wind can burn your feet. I measured even above 50 degrees near the ground, where I was laying on my mattress as the sun-heated air from the outside was carried inside the shelter
Resting…almost
During the afternoon the shadowy area under the overhang lessened, fortunately my head and upperbody remained protected
4 PM: Peak Heat. I managed to catch live the highest air temperature recorded by the data logger
Yeah, this selfie is more than necessary 🙂
Shelter or… prison?
A little after 5 PM the sun disappeared behind the rocky slopes and while the temperature was still very high, it started to slowly descend. I decided to leave the gorge and spend the night in a more open place to have a little advantage with the nocturnal radiation
Not my best decision: outside the conditions were even worse as the hot wind was blowing from the south-east. It was the hottest feeling I ever experienced regarding weather conditions. Out of curiosity I measured the temperature while the wind velocity was rising and saw that actually it was slightly decreasing, while the subjective feeling was of an abrupt heating. The 46 degrees felt like it was at least 60! This is the same thing but reversed as it happens during cold weather, when the moving air feels much colder (windchill). At higher temperatures than your body’s if no evaporation can happen to cool you off (sweating or wetting) your body temperature will be “attacked” stronger, you will fight harder to keep it at normal level. With an air so dry as it is here, your sweat is disappearing sooner as it can cool you, especially with wind.
And then came the “birthday-bonus”: a violent sandstorm hit my camp and took my mattress and pillow. For a few minutes I was laying on my luggage trying to keep everything on the ground, while also protecting my nose with the arms. Fortunately the gorge’s walls stopped the “flying carpet” between the boulders and I could recover it later
I was glad to see that the tripod survived the Khamsin’s blow (certainly the gorge was also protecting it), this was a solid proof for me that its stability is really good
After a difficult evening spent outside, I decided that the best strategy to finish this excursion is to start moving back to the asphalt road much sooner and not wait for the dawn when it will be “cooler”. It is so hot that you can’t even rest, sleeping is completely out of question. I need to drink almost constantly, the water (which was also hot until now) is decreasing. So I walked back around 8 km and stopped near the lake around midnight, some 1.5 km from the parking lot. Now came another big question: should I enter the lake to cool off? I knew the salt will be another risk factor. Fortunately it was again a good decision. The 33 degrees saline solution was enough to keep my body temperature controlled and while it was quite unpleasant feeling the salt crystals thickening on my skin (especially hair) after drying, the heat was the bigger threat.
After almost four hours spent inside the brine (mostly partially, regularly sprinkling it on my body) I even managed to sleep half an hour on the mattress when the temperature “dropped” to 38 degrees. The heat was trapped under the dust filled cloudy sky, the “venusian” ambience was absolutely surreal
Good morning Lac Assal…or something like that 🙂
Okay, the Garmin watch is still working…
With the local guys near the parking lot: I became “the biggest souvenir”, covered in salt like the goat skulls which they sell for tourists 🙂
I called my driver already in the evening to come after me this morning as the return to the Tadjoura road was too risky because of the difficult weather conditions combined with the uncertainty of the traffic in the off-season. He was very prompt and picked me up before 7 AM. After a well needed bath in the balmy waters of the Ghoubbet bay we were on the way back to Djibouti Ville
Khamsin is no joke: at a certain time we couldn’t see anything in front of us. Hard work, great experience
Birthday dinner at one of the best restaurants is the city: Signatures. The indian food (lobster on the right) is served professionally, it’s very tasty, strongly condimented. The mojito cocktail with ice was also impecable. However, will not tell you the price 😉
Next day I used public transport (the Tadjoura minibus) to visit the Ghoubbet bay area. Much cheaper this time as my plan is less difficult to carry out, I have smaller luggage and there is no need for precise timing. I started the hike at the “touristic beach”, well…not so touristic in the off-season (nobody, outside the two supervisors)
Not a norwegians dream, but still cooler than the air
Nobody also here. I could have waited at Lake Assal for “my lucky truck”…
This small volcanic cone near the road invited me to a visit
Definitely worth it, the view from the rim is spectacular. I decided to cross the rugged lava field to reach the other cone near the beach
Magical land, Godzilla is watching me
On the afar highway (lava flow)
Some parts are smoother…
…but most parts not really. This must be very new lava, probably from the 1978 November eruption of the nearby Ardoukoba volcano
The cool, turquoise color of the sea is very tempting as the temperature rises over the barren landscape. Of course, a refreshing bath is in the plan too
That’s precipitated salt. There is seawater inside the rocks below, just enough to wash my face
This structure is a double cone, the two craters form an “8” shape. I am standing now between them
View of the other crater with the bay were I planned to have the bath
After seeing some rubbish on the shore I decided to change to the other side, closer to the road
I hope the ground will not swallow me before 🙂
I know it’s 32 degrees, but still very nice to approach
Looks great, I even have the diving mask with me
No stress, even if I want
And again: a perfect shelter from the midday sun under the rocky ledge
The Zobject on the solidified lava
Paradise…for me
After about two hours of hedonism it’s time to leave and continue the hike. In just a few minutes the owerwhelming presence of the heat is back, the otherworldly, rugged surface only enhances the experience
As it is windy this must be close to reality. And it really was: at Lake Assal the logger recorded the second highest temperature (47.2 C) on this afternoon
Lunar or martian?
While approaching the road the terrain became even more irregular and fragmented
I can see some nice souvenirs for home 🙂
You need to be patient here, both for the terrain and the climate
The double-cone seen from the road
Beside acacia, this plant is one of the very few which can survive in the volcanic wasteland. I heard that it’s toxic, camels and goats avoid to eat them
Acacia was mentioned, here it is: the tough small tree with the distinctive umbrella shape is also known as “parachute tree” and, contrary to the one in the previous picture, it is very nutriend for the animals
Not too many cars on the road. No problem, I have enough water to reach the nearest settlement if nobody will pick me up.
Ardoukoba is somewhere there behind
Devil’s Island, the iconic landmark of Ghoubet bay
Around 4:30 PM I reached the small village, part of Lac Assal district. It was a very hot day, a need a cold Coke, maybe two
My wish was fulfilled and more than that: I was very pleased to talk in almost fluent english with a local youngster who even mentioned the “austro-ungarn” term what he learned in history class, when I told him about my hungarian roots. I wish him to continue the learning and use the knowledge for the development of his country
Finally, the Tadjoura minibus came and until dark we reached the outskirts of the capital. No AC on these cars, but they are moving fast with natural ventilation (windows down), thus except the parts inside the city when it waits or moves slowly the ambience is not oppressive
Next day in the more quiet part of the old center, I exchanged some dollars
These buildings retained the french, colonial aspect more than the newly renovated Menelik hotel
At the market. Here and generally in the center area, on the beaches, around buildings (well, almost everywhere) locals don’t really like to see visitors taking photos. The police will go a step farther: they will fine you. That’s right: basically it is forbidden to take photos in the city
One of the minibus terminals. The actual fares are very cheap (even more for the otherwise expensive Djibouti), but the drivers and their helpers often will try to overcharge the tourists. I’ve seen both during my stay, there were also honest ones. Local people are typically communicative and helpful
Taxis are constantly honking and the drivers sometimes can be a bit pushy in trying to take you inside even if you told them multiple times that you are okay or already have another way of transport. Not this guy 🙂
Another trip on the penultimate day: the starting point was the “the memorial of two japanese” (they died in a road accident) on the Ghoubbet plateau. I’ve chosen this exact place as I could show to the driver a picture taken from the Internet. First he was a little evasive, but later agreed to drop me here (maybe nobody does it before)
My main target is a viewpoint situated above the sea, which is at the end of the plateau about 5 km away, where it abruptly drops more than 600 meters. I found it on GoogleEarth, randomly checking the topography and concluded that it must be spectacular
There were a few steep slopes with unstable rocks, but generally the terrain is without serious elevation differences
Of course, you again
A last steeper portion
Nothing but a few goats
Oh yeah, that’s something! Today the haze is less, so I can see to the other side of the bay
Massive drop for sure. There could be a lot of fossils inside the exposed layers
The vivid turquoise sea is contrasting with the beige nuances of the barren land
Let’s have even more contrast 🙂
In the beginning I only saw two smaller birds (swallows I think) and then came the local boss
Devil’s Island is barely visible on the other side
I tried to identify some wild animals on the slopes, but couldn’t
Before 1 PM I started the way back, not exactly on the same path as the road is closer if I turn a little to the left. No need for the GPS now, the electric pilons are showing the direction
Gotcha! They (dorcas gazelle) were 4-5 under a big, lonely acacia tree, hiding from the strong midday sun when suddenly the stranger with the backpack disturbed their picnic
Yes, I like yours ears both from the front and the backside
Crazy: I think that I saw this exact tree on GoogleEarth!
I must disagree with Pierre Loti who stated in his writing “Obock for a day” regarding the acacia tree: “…is of no use, does not even cast a shade”. Well, it does cast a shade and a very nice one
Curious to see if the gazelles are hiding now in this valley. No, they were moving farther
These tracks in the sand could be theirs. Meanwhile the heat became oppressive, even if here we are above 600 meters elevation
Some afar nomads were here, but who knows when. In the summer the life is very hard
Just look at these plants and you will understand
Saw only a few, maybe they live more at higher elevations
The topography is less fragmented on the return way, after a single and smaller steep slope I am on a flat, dusty plain, from the other side of which the road is very close
Pure sand is not very common here, the terrain is mostly rocky
From the ground temperature I conclude that the air is probably not above 40 degrees Celsius now, but also not far
More dust devils were visible on this plain
Takîr in the turkic language, playa in the spanish, this terrain is composed of clay and is intermittently flooded. The cracks appear after drying
One steep climb and the asphalt road is near
Same thing as at Ghoubbet bay: only a few cars are passing and I have both time and resources. Tomorrow it’s my last day in Djibouti, let’s feel the african heat now!
Beside camels, goats are the single domestic desert survivors. I also saw some donkeys, but I think they are not wandering alone in the wasteland as the other two do
Close-up of the “toxic plant”. Meanwhile the “gendarmerie” situated at the meeting of the Tadjoura and the Ethiopian road is approaching. From there (after some cold Coke) I took a cheap minibus to the city
At Heron Beach: Last day in Djibouti. I’ve checked out from the hotel, also my local SIM expired today. Nothing left but recovering the equipment from Lake Assal. My driver will take me there in the afternoon, then we go directly to the airport
City Guest, I’ve spent a great week here. Many thanks for the manager, Leila and the staff!
Soon we are on the way to the hottest place of Djibouti. Haze again, that’s poetical
Karta village, the baboons were in the surroundings
More trucks now on this road, but I think they are coming from Tadjoura
The most important road sign in Djibouti
As we descend below the sea level the temperature rises
We can’t waste the time and continue on the salt pan. None of my two drivers were farther from the parking lot as no tourists were going farther
That means the adventure is mutual. Soon we are driving completely off-road on the sharp salt crust
Time is starting to press us a little as we are not sure how close can go with the car, the terrain becaming more insecure. I am prepared to do a 8-10 km walk if necessary, but that would take some time. Finally we managed to go sufficiently close (around 1.5 km), only the black mud is separating us from the gorge
Ready for the last trip, a short one
Sunset is close, I must be fast
Success: the tripod is still standing on the wadi floor, the device functional, everything intact
All data was correctly recorded. The 47.4 degrees from 21st was not exceeded later, while the minimum was 33.3 degrees Celsius
That’s all folks, it’s time to stop the logger
View of the sensor after dismounting the Barani helical shield
With its afar friend
Bye George, I mean Gorge!
Labyrinth inside the gypsum layer
Still daylight, the car is close
Houmed, a reliable driver and a nice person. It was a great collaboration, many thanks for the help!
We left Lake Assal in the dusk, Ambouli airport is waiting for us
Bye Djibouti. It was a hot journey for sure…

To be continued…

Lake Assal: nothing cool, but still cool (1/3)

Intro: the warmest capital city

Together with Khartoum in Sudan, Djibouti city is the hottest capital in the world, having a yearly average temperature just a little shy of 30 degrees Celsius. While the “winters” are warm (kind of an european summer), the hot season is sweltering and the high humidity, characteristic for the coastal areas make the tropical ambience even more oppressive. The heat doesn’t go away even in the night, thus the living is very challenging without air conditioning, especially for non-natives. In the dark it almost feels unreal, like you are trapped inside a giant sauna without walls.

The city has a population of around 600.000, represented mostly by issa (somali) and afar ethnic groups with some arabs, french and other minorities beside. The former french colony is a busy strategic port close to the Red Sea’s Bab-el-Mandeb strait and more countries have military bases here. Before known as “French Somaliland”, after gaining the independence in 1977 the small country received the same name as its capital. Unknown for many travelers, the tourism is not very well developed here, but is rising in the recent years. Security is taken seriously, police presence is common. Djibouti’s downtown is quite noisy, with many honking green/ white taxis and old minibuses looking for the next passenger. Ambouli International Airport is close to the city and greeted me before midnight on June 18th with the first dose of african heat.

Mosque in the center area of Djibouti Ville

Choosing the target

The most iconic place associated with heat in the meteorological sense is undoubtedly the Sahara desert. An endless, empty place with the size of a continent presenting huge, sunbaked sand dunes and barren, rocky terrain. Temperatures are known to be very high there, often exceeding 50 degrees in the shade. Wait. Is this really true? Well, partially. Actually there were only a few cases when reliable temperatures above 50 degrees were measured here, the 51.3 degrees Celsius recorded in Ouargla (Algeria) on 6 July 2018 being the most certain one. Some old readings like the famous 58 degrees from El Aziziya were infirmed in the later years after specialistic investigation of the used equipment and measuring conditions. Long story short: naturally occuring +50 C air temperature is less common than people think.

Regarding my personal research, from the three main extreme categories (Cold, Heat, Amplitude) heat was the last to come. Actually it’s not exactly the first time, a few years ago I’ve visited the Ethiopian side of the Danakil depression with the same purpose, but the research was unsuccesful as I couldn’t collect the equipment from an inactive volcanic crater because of … let’s say “bad luck”, having to deal with unreliable local collaborators. Thus it’s understandable that I felt a strong need to come back to the Danakil and “finish the job”.

The sunken desertic area of tectonic origin is situated on the territory of three countries: Ethiopia, Eritrea and Djibouti. While the first one has the biggest portion, Djibouti owns the lowest spot, represented by the shores of Lac Assal at 155 meters below the sea level, also the deepest land in Africa and second in the world after the Dead Sea’s depression*.

The relief of Djibouti with Lake Assal in its center (teal color represents below sea level areas)

While second to the Dead Sea regarding the elevation, the raport between the two is reversed when we are talking about the salt concentration, Lake Assal being the saltiest lake of considerable size in the world (ten times more than the ocean), surpassed only by two small ponds (one in Antarctica, the other also in the Danakil), so one can easily float on the surface without sinking.

I have an old passion for below sea level places, which usually have a very hot climate (Death Valley in the USA is the best example). Why? There are two main reasons for this: first because of the general rule that normally temperature drops with elevation (6.4 degrees by 1 km), secondly because these places are parts of very dry, desertic environments, strong evaporation being a basic condition for their formation. A consequence of the latter is that they are often associated with salt marshes, the residue of the former lake. Badwater in Death Valley (-86 m), the southern part of the Dead Sea (around -400 m), Aydingkol in the Turpan Basin (-154 m) and Lake Assal (-155 m) all have these same two things in common: salt flats and extreme summer heat.

Soviet 500K topographical map of the Gulf of Tadjoura with Lac Assal on the left-center part

Dallol in the Ethiopian Danakil is considered to be the place with the highest average temperature in the world with a whopping 34.6 degrees Celsius, according to the short period of measurements from 1960 to 1966. June is the hottest month with a mean maximum of above 46 degrees, very similar to the well known “heavyweights” of the domain like Death Valley, the Kuwait-Iraq-Iran border area near the Persian Gulf (July-August) or the Jacobabad-Sibi plain in Pakistan (May-June). However, unlike the former mentioned ones which all reached 52-54 degrees at a certain time, no temperatures above 50 were ever recorded in Dallol, 48.9 C being the highest measurement. An unusually small gap of less then 3 degrees between the typical and the extreme values for sure, even for only 6-7 years of data. The heat is “at home” here, it’s never coming from somewhere else as in the case of most places (like Saharan origin heat in Europe for example), this must be the main reason for this constancy.

While before I’ve chosen the more interior part of the Danakil (Afdera Lake area) to completely avoid the moderating effect of the sea, now I knew that Djibouti’s Lac Assal is definitely not “too close” to the coast as in the summer months the wind (known as Khamsin) is blowing from the land, heating and drying everything on its way. The difference between the two regions is in the cooler part of the year when the wind is coming from the east (Indian Ocean), internal areas remaining warmer than coastal ones. Lake Assal’s southern shore is situated only 10 km away from the Ghoubbet-el-Kharab bay, an almost completely closed part at the very end of the Gulf of Aden. Actually the highly saline lake gets its water from this bay through the tectonic fissures.

The salt flats west of Lake Assal with the red dot marking the location of the data logger in the gorge

The general area was defined, let’s look at the small scale features. Basically I want to set the equipment at a little distance from the lake (respectively the salt pan) to have such ground below, which can heat up more (sand or gravel). Beside this I try to identify some topographical enhancement, without loosing too much elevation. After looking thoroughly everything around on GoogleEarth I found the right spot inside a gorge, just a few hundreds of meters from the salt flats. The dried riverbed’s name (known as “wadi” or “oued” in the arab world) is Kadda Galeita. Regarding the elevation the satellite data is not so precise here because of the small sizes, thus I partially concluded from the visual aspects that this place must be the best one for my purpose. Beside the general “canyon effect” (part of the solar radiation is reflected back by the walls), the concave curvature of the gorge is looking exactly to the NW, from where the strong sun will strike the slope in the early afternoon hours. Despite being on the Northern Hemisphere, because it’s inside the tropics, in this period of the year the sun passes slightly to the north above the land and June 21st is when the northern deflexion is the biggest.

In Djibouti the meteorological measurements are scarce. It seams that outside the capital’s airport there are no other weather stations at all, anything else is based on hypothetical approximations (both the regional forecasts and the climate diagrams). The city’s highest recorded temperature is 46 degrees Celsius (June and July), also just a few degrees above the summer months average maximums (40-42 degrees), a characteristic of the lower latitudes.

At present industrial scale salt extraction is happening at Lake Assal, consequently in the recent years can be reached on paved road. However the area is still kind of remote as there is no public transport from the Tadjoura main road, usually only expensive private tours and taxis are taking the tourists there. My target is about 10 km far from the “parking lot” (the end of the asphalt road).

*The Sea of Galilee (-212 m) often mentioned as the second lowest basin in the world actually is a part of the bigger Dead Sea depression. They are linked by the Jordan river, so can’t be considered a separate basin. However it is the second lowest lake.

Brief summary of the research

I arrived in Djibouti on June 18th in the late evening and after two days of rest and some acclimatization in the muggy heat of the capital, in the early morning of June 21st I was heading with a private driver to Lake Assal, which lies about 110 km west from the city.

After leaving the main Ethiopian road with heavy truck traffic, we continued on the Tadjoura way around the gulf of Ghoubbet, then turned left and reached the end of the asphalt road on the lake’s southern shore after 8 AM. From here I started the hike on the salt pan towards the target situated inside the gorge.

Haze on the salt flats of Lake Assal

The weather was already hot and became oppressive while reaching the exact location in the wadi after 10 AM. There were only a few clouds, but the characteristic summer haze caused by the hot and dry khamsin wind was present. However, I felt only weak air movement until now.

The bubble-aluminium foil protected data logger (I positioned the device’s screen to face south) and the Barani solar radiation shield under which its sensor was sheltered were mounted on a tripod whose legs were farther stabilized with nearby rocks.

The weather station in the gorge

The exact coordinates are: 11.686346 N, 42.341225 E, the elevation around -130 meters. The height of the sensor from the ground is 160-170 cm. At 10:43 AM the mini weather station started its operation. First reading: 42.4 degrees Celsius.

I waited in the shade nearby the research equipment until late afternoon, meanwhile checking the temperature more times and measuring also the ground in the early afternoon. With some luck I caught the highest air temperature live: 47.4 degrees Celsius around 4 PM and saw 73.9 C on sandy surface around 1 PM. The sky was partially covered in the hottest period, but the clouds coming from the NW never managed to block the sun.

The highest temperature of the day and of the entire measuring interval

After a sandstorm, which hit my camp in the early evening, I’ve spent the following night outside, hiking back to the asphalt road until the morning were my driver picked me up. The evening and night was still extremely hot, this phenomenon felt even more outlandish than the peak heat of the day.

I couldn’t sleep or even rest until dawn as the temperature never dropped below the human body’s and the hot wind was making the real feel even worse. Meanwile the sky became cloudier. This night’s minimum temperature in the gorge was 39.4 C !

My diurnal shelter, an overhang of the rock wall

I’ve spent the next days sleeping in the city with two separate trips to the Ghoubbet-el-Kharab bay using public transport: one to the volcanic area with new lava fields on the western side of the gulf and one to the higher plateau on the south-eastern part. Because of the proximity to the ocean, the capital is much more humid than the internal areas, having the heat index higher for the same temperatures. Here you are constantly sweaty, while at Lake Assal the khamsin sucks out all moisture from you.

I returned to collect the equipment on 26th in the late afternoon (haze again) and found the tripod standing in its place on the wadi’s floor with the logger functional and everything intact. The research was successful, all data was correctly recorded. The first day’s 47.4 degrees wasn’t surpassed on any other day, but was approached on 23rd with 47.2 degrees. The lowest daily maximum was 44.3 on 22nd, while the minimum of the entire measuring period 33.3 degrees Celsius in the morning of 25th.

Dromedaries grazing in the desolate landscape

During my staying in the Lake Assal area I didn’t encountered any wild animals outside of four camels and hearing some high pitched bird noises inside the gorge. The vegetation is completely missing on the salt flats and is also very scarce on the sandy-gravel surface. No acacia trees, only some small tufts. At the end of the asphalt road live some locals (mostly youngsters) who sell salt and other mineral related souvenirs and there is some activity at a chinese salt extraction plant. No other tourists were present as it is low season because of the heat.

The instruments used on the field

-One LogTag UTRED30-16 data logger with the measuring range between -40 and +99 degrees Celsius, an accuracy of 0.5 degrees Celsius and a resolution of 0.1 degrees Celsius.

-One Greisinger GMH 2710-T digital precision thermometer with the measuring range between -199.9, +200 degrees Celsius, an accuracy of +-0.1 degrees Celsius and a resolution of 0.1 degrees Celsius.

-One photo camera tripod serving as the support for the instruments.

-One helical solar radiation shield from Barani Design Technologies: https://www.baranidesign.com/

Sand surface measurement with the Greisinger precision thermometer

To be continued…

Burgastyn Els, Mongolia’s highest desert (2/3)

Journey photo album

 

Every year new ice sculptures appear on the Chinggis Square, Ulaanbaatar

 

Gandan monastery

 

We are here but the flight is delayed to the next day because of snowstorm in Zavkhan aimag

 

Arriving at Donoi airport, Uliastai

 

On the way to Erdenekhairkhan (85 km of emptiness)

 

Arriving in the small village

 

Maybe this will be my home for the next two weeks

 

Halo, a very common optical phenomenon in the mongolian winters

 

Some of my roommates. I think all of us like the cold

 

Near Mukhart river source in the next morning (30 km snow covered track). This will be the starting point of all my trips to the research area

 

Pretty chilly, it was -25 degrees in Erdenekhairkhan, which is not a particularly cold place as it lies on a plateau in slope. The next night can be promising

 

At sunrise, approaching the natural amphitheatrum of Mukhart

 

Another nice optical phenomenon

 

I know this scenic place from two years before. One quarter of the way is done

 

The windchill is playing with my senses

 

Okay, so that’s my direction. Burgastyn Els desert in front of me

 

Despite the isolation, the dunes are covered with many animal trails

 

Looking back, more than half part is done. Pretty tiring terrain for a heavy backpack and big snowboots

 

Deers are common in this area

 

But most of the trails are made by these…

 

…and these guys. Horses and yaks are left to graze on the dunes unsupervised

 

In the afternoon I reached the planned camping spot on the southern col of the chosen basin

 

First view of the unnamed sandy depression

 

Arriving at the bottom. Looks good, the weather also

 

At 5 PM the mini weather station started its activity: -28 degrees now

 

Soon after the sun disappeared the temperature was falling fast

 

-33.5 degrees at 17:40, still sunshine on the ridges

 

Time to go back to the tent (1 km in straight line)

 

Only a thin layer of snow here, the wind cleared the exposed parts. On the bottom is 20-25 cm, but some areas have even above 50 cm

 

Dinner time: dried fruits, one of the best and simplest solution for extreme cold

 

The first part of the night was completely clear and calm, later cirrostratus clouds were invading the sky. Near surface measurement at my camp (dawn). In the basin must be much colder

 

That’s right, went well below -40. Still no wind, but because of the thicker cirrostratus the morning temperature was only -35 degrees

 

The surface was two degrees colder, very common on the negative topography (convex and inclined terrains can have much more differences)

 

After 10 AM I started the way back. The tent will remain here, I trust the calm of the anticyclone

 

My closest neighbor

 

These are the most tiring parts: steep, snow covered sand. Beside the legs it needs also significant upper body strength

 

Lunch time

 

Some parts are completely full with horse and yak trails

 

Mukhart’s outer (convex) contour is closer and closer

 

This view is always welcomed. Now also means that the most difficult part is over

 

First and last guy seen during the two day trip. He came on horseback to the base of Mukhart, than climbed the abrupt part on foot

 

He has an efficient style to descend 🙂

 

I can see the car. Actually I saw it first from the rim of the amphitheatrum

 

Good to see that the driver is very conscious, coming here much sooner to wait me with warm food

 

A very rare ocasion here: another car

 

Playing cards is the main program in a yurt. Unfortunately usually accompanied by smoking…

 

Magpie is the most common bird here in the winter

 

And I can’t miss out this: Erdenekhairkhan’s weather station

 

Yurt change the next day: too many children (including an infant) made the essential rest impossible. Sorry guys…

 

My street

 

Domestic goats on the hill near the village. Much smaller and with thicker coats than european ones

 

Yeah, that’s a vulture. Only 100 meters from the settlement

 

Altan Khairkhan (Golden Holy Mountain), a proeminent landmark

 

Back to the cards. And smoke. Okay, it’s not that bad

 

Village center

 

Traditional lifestyle

 

Climbing a rocky peak a few km from the settlement. Ibexes are living here…

 

…but not today

 

Second research trip: Mukhart again

 

Much cloudier today, but the following night looks promising

 

Yaks again, more exemplars this time. The snow partially disappeared from the exposed slopes. Beside the sun and the wind, the animals are also contributing to this, eating it in place of water

 

I got you!

 

The backpack is less heavy and I can follow my tracks from the previous trip. Feeling stronger I climbed the rocky peak instead of circumventing it. Worth it

 

A snow shower started, but it was short and weak

 

I found my tent moved from its original place. The south-eastern wind carried it inside the neighboring hollow. Maybe a better place to spend the next night, if it’s windy

 

Goji berries, pecan nuts and a local meal “aaruul” (kind of dried yoghurt) is the menu today. Let’s check the tripod with the thermometer

 

-38.5 degrees for the missing period (13-17 January)

 

Observing on GoogleEarth,  I was curious to see what kind of vegetation is on the slope of the nearby mountain. As I later understood from the locals, this is exactly the “burgas” (bush), which gave the desert’s name

 

I also made a walk to the northern col (another 1 km in straight line) to measure its elevation (center of image). It was almost the same as GoogleEarth showed: 2221 m. That means the tripod is 27 meters deep inside the basin

 

This hollow is the actual bottom of the basin (2192 m), but I left the tripod in the original place because of the better sky view factor

 

Warmer than the first time: -21 degrees in the afternoon

 

Back to the camp. I’ve moved the tent only a few meters from the place the wind was carrying it. Here is more protected, relatively flat and still not on the hollows bottom

 

The evening and the first part of the night was fine (clear and calm), but after midnight the wind started to intensify and till the morning completely destroyed the inversion of the basin. Minimum of the night: -40.9 degrees Celsius

 

Because of the wind I was constrained to pack the tent (it wasn’t able to stay in place even in the hollow). On the way back I met the horses again

 

The driver was there well before my arrival, this time with the second yurt’s owner

 

Lunch at the mayor’s house the next day. They heard about my activities and invited me

 

This time I was lucky and saw the ibexes on the rocky slopes (younger ones)

 

The last research trip started with some difficulty because of the snowdrifts. But we were three and solved the problem soon

 

Warmer today, very low temperatures are unlikely for the following night

 

The amphitheatrum have some visitors this morning

 

I had the strategic advantage observing them from the rim, therefore plenty of time to make pictures

 

Partially cirrus covered sky today. This setting will continue also in the night

 

Hind (female deer)

 

The horses are still in the area

 

Now it’s calm, I will leave the tent on the ridge again

 

-39.6 degrees is the minimum for the missing period (18-22 January) and only -16.5 now

 

I’ve climbed to the highest peak of the western ridge (around 2390 meters) to see Ulaagchiin Khar lake on the other side

 

View in the opposite direction

 

The researched basin from the ridge. You can observe the “burgas” vegetation on the mountains slope

 

-26.3 degrees at dusk. Not very cold, but the decrease was significant (10 degrees in less than two hours). I didn’t slept much this night. Beside that I’ve often checked the sky, wolfs were howling an entire hour in the latter part

 

And here is the main event of the night and maybe of the entire research: the small hollow beside my tent had -37 degrees (at head level) in the early morning and -39 degrees near the snow surface. That’s a solid 20 degrees lower than the temperature at my camp (only 50 meters away!) where it was -17 degrees. Even weirder is that there was colder in the early evening (-19 degrees), despite the clear and calm conditions during the entire night

 

The main basin reached -36.8 degrees. That means the small one was the same, actually even slightly colder (!)

 

This was a characteristic night with generally constant temperature drop. The instant morning temperature was close to the minimum (around -36 degrees)

 

It’s time to say goodbye to the big…

 

…and small hollows

 

Sixth and last time on the same track, became familiar until now

 

The more exposed parts of the dunes lost the snow cover during the last days

 

An entire labyrinth of trails in this area

 

You again

 

Mukhart for the last time. Remember how white was in the first day?

 

This wild cereal is very common on the dunes

 

That’s it guys. Still alive 🙂

 

The way back to the village…

 

…and to Donoi airport in the next morning

 

Otgontenger (4008 meters), the highest peak in the Khangai mountains and one of the most sacred in Mongolia

 

See you next winter!

 

To be continued…

 

 

 

 

 

 

 

 

 

 

 

 

 

Burgastyn Els, Mongolia’s highest desert (3/3)

Evaluating the measured values

 

First research night (12-13 January)

The tripod with the minimum thermometer was set around 5 PM at the bottom of the basin. The sky was clear, no air movement, still sunshine at that time. The alcohol column of the instrument showed -28 degrees Celsius. Shortly after the installation became shadowed and until 17:40 (when I left the hollow) the temperature decreased to -33.5 degrees. Near the snow surface I measured -36 degrees.

The first part of the night was completely clear and calm at my tent. After 3 AM (it was almost full moon) I observed some cirrus, than cirrostratus clouds invading the sky. At dawn I measured -17 degrees at head level and -23 close to the surface near my tent. In the hollow was -35 degrees in the early morning (-37 close to the surface), while the minimum of the night reached -41.9 degrees Celsius. This will remain the lowest temperature captured in the entire research period. In the same night Tsetsen Uul (the most representative weather station of the area) reached -38.4 degrees.

 

The lowest temperature of this research: -41.9 degrees Celsius

The 13-17 January interval

I left the research area in the morning of 13th January. As I had no logger to record the temperature curve, the single certain data what I will have after my return is the minimum value for the entire missing period. I visited the hollow for the second time in the afternoon of 17th January, when I found the index of the instrument stopped at -38.5 degrees Celsius. I can’t be sure which night gave this value, can’t even exclude the same morning when I left the basin. However most likely happened on the night from 14 to 15 January, when Tsetsen Uul reached -37.2 degrees.

Second research night (17-18 January)

The afternoon was changing from full sunshine to partly cloudy (cirrus-cirrostratus with some altocumulus lenticularis) and was warmer than on 12th, with the temperature around -21 degrees. The evening started well with clear sky and still air, but later in the night it became windy. No clouds till the morning, but the intensified wind completely destroyed the inversion of the basin. The temperature raised from the -40.9 minimum value to above -20 degrees before the sunrise. The same pattern can be observed in the statistics of Tsetsen Uul, which recorded -36 somewhere in the early night hours and warmed up to -19 degrees till the morning.

The 18-22 January interval

I left the research area in the morning of 18th and visited the hollow again in the afternoon of 22th January, when I found the thermometer’s index stopped at -39.6 degrees Celsius. This almost certainly happened in the morning of 19th January, when Tsetsen Uul recorded -35.6 degrees.

Third (last) research night (22-23 January)

The entire day was generally fine, also much warmer, with the afternoon temperature of -16 degrees. There were only intermittent light air movements, but thinner cirrus and cirrostratus clouds were partially covering the sky constantly. This setting continued also in the night, when the sky was starry, but slightly blurred. No wind till the morning. I’ve measured -17 degrees near my tent at dawn, which was a surprisingly high value, as I saw 2 degrees colder in the early evening hours in the same place (!) In the basin the minimum thermometer’s index was stopped at -36.8 degrees, while the temperature at the moment was also close to this value (around -36 degrees). This was a good night, very likely presented the characteristic temperature curve, but because of the too high starting temperature couldn’t reach too low, despite the 20 degrees of decrease.

But the most impressive happening was when I descended in a hollow between the dunes, just beside my tent. Certainly no more than 10 meters deep and with the drainage area not bigger than a soccer field. To my great surprise at the bottom of this banal concavity the head level temperature was -37 degrees Celsius at 8 AM (already -35 in the earlier part of the night), a full 20 degrees lower than on the nearby ridge and even slightly colder than the minimum for the entire night in the big basin with hundreds of times more drainage area! Meanwhile the near surface temperature was -39 degrees.

 

General conclusions

Compared with Tsetsen Uul the Burgastyn Els station reached lower minimums in all the 5 described intervals. The smallest difference is 1.1 degrees, the biggest 4.9 degrees, the average 3.0 degrees Celsius. In three of the five cases the difference was bigger than 3 degrees. According to the statistics on Ogimet Tsetsen Uul had only 8 cm of snow cover that time, while the researched basin had around 20 cm. In my opinion this could give an advantage of 1-2 degrees, but not above 3 degrees.

It can be noticed that the three bigger differences coincide with the three coldest measurements in the frost hollow, while the remaining two with less impressive discrepancies are the ones, when the cold was less severe. Tsetsen Uul’s lowest reading was also on 13th January, but was 3.5 degrees milder than in the high desert.

 

The minimum temperatures of 13th January in Central Asia (source: Ogimet). None of the stations presented on the map reached lower than my measurement in the same night. Note: not all mongolian stations are on the map. I heard from trustful source that Otgon village recorded -43 during this night, which was the lowest temperature in the country

The most radical conclusion results from the comparison between the small hollow near my tent and the much bigger and deeper researched basin. It is true that it was only a single night, but as the two places are very close, the snow cover similar and the general conditions were characteristic, I am strongly inclined to believe that approximately the same thing would happen during any nights with good potential for strong thermal inversions. I also think that most of the same sized and shaped hollows (which are very common in this desert) will cool the same way as the observed one.

This case is especially interesting as the place is situated right on the saddle, not in an already cooled air mass as it would be somewhere inside the bigger basin’s endorheic sector. Most likely all that impressive “thermal plunge” came from the potential of the small scale topography. Beside these this hollow don’t even have a particularly good sky view factor, as a decent percentage of the slopes have the inclination above 20 degrees.

 

Snow surface temperature in the small hollow near my camp

I have three main conclusions related to the above mentioned facts:

-First is that (regarding the drainage area) size doesn’t really matter at all.

-Second is that a 8-10 meters of depth is enough to approach the maximum potential of a frost hollow. The thermal drop will happen in a more abrupt way than in the deeper basins.

-Third is that relatively steep slopes are suitable (maybe even necessary?) for fast and efficient cold air pooling, despite the altered sky view factor.

 

As a summary this season was a modest one without a single really good night in the researched period, but the last one’s teaching compensated me for the lack of minuses. A return to the area (hopefully with all the necessary devices this time) is likely.

 

Burgastyn Els, Mongolia’s highest desert (1/3)

Choosing the target

Mongolia again. All in all it’s the country with the best potential for my plans. Home to the Siberian Anticyclone’s center it offers the biggest chances to experience strong winter temperature inversions. The area is huge, the places remote and wild, relatively untouched by the modern world. The natural advantage is enhanced by the appropriate socio-political situation, where visitors can experience real freedom.

 

The high altitude desert with Ulaagchiin Khar lake, the track from Erdenekhairkhan village (red curve) and the location of the research area (red dot)

Two years before, while researching the sand dunes north of Erdenekhairkhan I had great luck with a powerful cold snap, when at the bottom of a 60 meters deep hollow my logger registered a stunning -53 degrees Celsius, the lowest temperature ever seen by my devices.

This year’s plan is to set the equipment in another sandy depression a little farther to the north-east, where the dunes are touching the slopes of a mountain ridge. The easternmost, respectively highest part of the desert is called “Burgastyn Els” (meaning “bushy sands”). As the desert itself has no bushes, its name’s origin must be the fact that it’s situated just below the partially bush covered mountain, which is named the same way: “Burgastyn Uul”. The chosen basin is about half the depth of the previous one, but with a bigger drainage area. With its bottom situated around 2200 meters, it’s also the highest between the sand covered hollows with considerable depth (more than 20 meters).

Actually the sand is “climbing” the mountain, as you can see the dunes continuing their eastward way on the other side through the saddles, reaching and invading the remote Ulaagchiin Khar lake. Even the 2600 meter high top has a sandy overlay.

 

The chosen high altitude basin with the contour intervals (1, 5, 10, 15, 24 meters) calculated on GoogleEarth

 

Brief summary of the research

Just a few days before the asian journey the sensor of my logger became damaged and the bad timing made impossible to repair or substitute the tackle. That meant I was constrained to leave at home also the Barani radiation shield and rely mainly on the alcohol based minimum thermometer. There will be no temperature curves, no daily maximums, only the lowest values. Fortunately this is the most important thing, so let’s be positive. I also have the digital precision device for instant measurements, which is my favorite tool while on spot.

I arrived in Mongolia in the morning of 7th January by the Budapest-Ulaanbaatar (through Istanbul) international flight. From the mongolian capital I used domestic flight to Zavkhan aimag’s capital, Uliastai. At the airport a private driver was waiting for me, who was contacted by a tourism company from Ulaanbaatar. Previously this company supported me to obtain the visa at the mongolian consulate in Budapest and helped to arrange the transports and accomodations in the country during the entire journey.

The Toyota Land Cruiser owner came from Gobi Altai province and had taken me to Erdenekhairkhan (around 85 km’s), which is the closest settlement to my targeted zone. From the village we approached the research area with the jeep, following a snow covered track (around 30 km’s) not far from the Mukhart river’s source, a scenic place with interesting geomorphology. We managed to get close to the target around 13 km’s in straight line. From this point I reached the chosen place alone by foot crossing the dune field, carrying the camping equipment and the meteorological devices in a backpack.

 

Burgastyn Els desert

Even so the area is very remote, it still have some human activity in the wintertime. In contrast to the Nariyn Golin Els I didn’t saw any yurts here, only two shepherds on horseback during the entire six days of hiking through the dunes. However many horses and yaks are grazing unsupervised in the desert, many kilometers from the closest populated place.

Despite its isolation and severe climate, in most parts the surface was full with animal trails. Actually the single area which was completely lacking the domestic animals presence was the chosen frost hollow. Starting from the southern col there were only a few trails, most likely of deers.

 

View of the hollow from the southern col

I raised my tent near this southern saddle, around 1 km from the actual research place, at 2250 meters above sea level. The tripod with the attached minimum thermometer was set on the bottom of the frost hollow, at 2194 meters elevation (GPS on spot). During the second trip I’ve visited also the northern col, which represents the outflow point of the depression. According to my measurements the endorheic depth is 28-30 meters (about 5 meters more than GoogleEarth shows).

The tripod’s coordinates were: 48.286 N, 96.005 E. The thermometer’s elevation above the surface was around 160 cm. The instrument was measuring the minimum temperature from the afternoon of 12th January until the morning of 23th January. The precision electronic device was used to take instantaneous measurements of the air (holding the device in hand at head level while moving) and near the surface (leaving the instrument on the snow).

 

The tripod with the minimum thermometer on the bottom of the basin

On average the snow in the desert was rather big (for mongolian standards), reaching 20-25 cm on the bottom of the frost hollow. The weather was generally good, mostly clear or partially covered by cirrus and cirrostratus clouds, but pretty windy sometimes with some short and weak snowfall intervals. Regarding the temperatures this season wasn’t a lucky one, the clear and calm conditions were only partially covering the nights.

The research period was encompassing eleven consecutive nights. From these I spent three in my tent, the remaining ones in Erdenekhairkhan (yurt).

 

The devices used in the field

-One Greisinger GMH 2710-T digital precision thermometer with the measuring range between -199.9, +200 degrees Celsius, an accuracy of +-0.1 degrees Celsius and a resolution of 0.1 degrees Celsius.
-One meteorological alcohol minimum thermometer, USSR, 1988, with the measuring range between -50, +40 degrees Celsius.
-One photo camera tripod serving as the support for the instrument.

 

Temperature near the snow surface

 

To be continued…

Liquid frost: the hyper-cold brine ponds of Sangiyn Dalai (3/3)

Conclusions regarding the brine ponds

After returning home I correlated the new discoveries with my previous observations on the salt flat. I had some presumptions even before, but now I realized the big picture. Let’s analyze the puzzle in parts:

Case 1:

When I first visited the area in January 2011 I found a decent sized pond, which I observed/ selected beforehand using a detailed satellite image. The imagery’s date is 2010 May 27, so it was less than a year old, when I went there. The circular lake I found was more than 10 meters in diameter and (as it was only partially frozen) I estimated the maximum depth to be more than 2 meters. The temperature of the upper layer was -21 degrees Celsius. I returned here about 10 days later and found the pond frozen, except a small portion near one shore, where I measured -22 degrees Celsius close to the surface.

 

One of the biggest brine ponds of the salt flat, now inexistent (January 2011)

Next winter, In January 2012 I revisited this place and found this lake completely frozen, covered with a thick layer of salty ice. The ice was so massive I could safely walk on it and dig holes on its surface to study the brine beneath. The temperature under the ice was -23 degrees Celsius. This was an expected value as the solution beneath the ice became even more dense, conversely has even lower freezing point than before. But I was a little surprised to not found a single place where the depth exceeded 130-140 cm. I thought maybe it’s caused by more salt deposition on the bottom as the brine became even more denser during the freezing-point depression.

This particular pond wasn’t visited in the following years, I returned here only this winter, in February 2019. There was no lake, not even a shallow, frozen one. I rechecked the coordinates in my GPS at home and correlated with the imagery, but it was no doubt: that water body disappeared.

Case 2:

In January 2014 I was back to the salt flats. This time I accidentally discovered a new lake, which I recognized to be one of the bigger ponds visible on the same 2010 May 27 imagery. The 8 meter diameter circular pond was unfrozen and I measured below -23 degrees Celsius close to the surface. The shores were steep, the bottom at the deepest portion wasn’t clear because of the considerable depth, which was probable more than 2 meters.

 

This lake still exist, but now is less deep (February 2019)

In February 2016 I returned to see this lake. This was an exceptionally cold winter with -46 degrees recorded at Zavkhan weather station at the end of January. The lake was now covered with a thick layer of salty slush, but its temperature was only -18 degrees Celsius, a few degrees warmer than before, unfrozen. Maybe because of the changing in the surface layer’s composition? Or because of the higher solar angle in late February? Not sure. I checked the depth of the lake using the poles of my tent and found out that the ground was very uneven on the bottom. In some places it was 1.5 m, in others (just a little farther) less than 1 m. But far from 2 meters at any point.

Case 3:

In January 2014 I searched for eutectic frozen brine, so I was looking for very shallow ponds. However I was surprised not to found a deeper lake in one particular area, as I remembered from the imagery there is one. There were some shallow frozen ponds, but none of them had considerable depth (less than 0.5 meters) as I was expecting.

 

The newly found lake is situated in an area, where on the old imagery are visible some water bodies of variable depths, but this one wasn’t there in 2010

This winter, in February 2019 I discovered this new, 2 meters deep brine lake (where I’ve accomplished the dive), which I thought to be the one I couldn’t found in 2014. But after analyzing the exact coordinates I figured out that this lake is not exactly on the same place, where the deeper pond on the imagery appears. Also the shape is different. And the deeper pond (according to the imagery) is no longer there. This lake has the slush temperature of around -22 degrees Celsius, with the incredible bottom temperature of +2 degrees. As this sensor with the 3 m long cable is a new one, I have no infos regarding the bottom temperature of the other ponds in the former research years, but I suppose, that in the case of the deeper ones, the stratification can be similar.

Case 4:

This winter, in February 2019 I discovered this partially unfrozen, new pond of around 4 meters in diameter, with the surface temperature of -24 degrees Celsius. After returning home I found out that at those coordinates there is no lake on the 2010 imagery, not even a tiny one. The imagery has a 0.5 meters resolution, so even smaller features are identifiable (like camels or bovines). It’s clear: on that date this pond didn’t existed.

 

The “new-born pond”

Taking into account the above mentioned facts, regarding the geomorphological/ hydrological aspect my major conclusion is that the lifespan of these brine ponds is small (usually less than a decade), they are constantly forming by the action of the springs under the salt crust (underground erosion/ dissolution) and disappearing by the formation of new salt deposits on the bottom of the water bodies (colmatation with evaporites).

 

The aerial view of a part of the salt pan from 2010 May 27: black arrow pointing to “Case 1 pond”, yellow arrow to “Case 2 pond”, teal arrow to “Case 3 pond”, red arrow (+ sign) to “Case 4 pond” (coordinates of this point) and the blue triangle is the location of my tent in 2019            Zoom in for a better view

Regarding the water temperatures my observation is that the surface layer generally reaches the slush state between -20 and -25 degrees Celsius, in most cases around -21, -22 degrees. There are some smaller ponds, where I saw liquids even close to -29 degrees Celsius. As the water bodies are not far from each other (sometimes it’s only a few meters between them), I consider that the general ratio between the solution’s components must be (almost) the same and these fluctuations between the freezing points are mainly caused by general concentration and not ratio changes between the constituents.

Another thing I could mention is that when the surface layer reaches the slush state at a certain temperature, the deeper layers must have an even lower freezing point as in the case of salt water the density rises constantly with the temperature decrease, so if the deeper, unfrozen layer is still heavier than the upper one, its freezing point is certainly lower. This also means that the surface layer’s slush can never reach the maximum possible concentration of the solution.

 

Note: After I get the water sample analysis results from Budapest (hopefully soon) I will update this section.

 

 

 

 

 

 

Liquid frost: the hyper-cold brine ponds of Sangiyn Dalai (2/3)

                     Journey photo album

 

Ulaanbaatar. Tsagaan Sar (Mongolian Lunar New Year) with my guide, Gansukh’s family

 

The center of Khovd, capital of the aimag with the same name and also of entire Western Mongolia

 

Street in Khovd with Ulaan Uul (Red Mountain) in the background

 

Mosque in the town. A significant kazakh minority lives in the town, who are muslims

 

On the way to Sangiyn Dalai. Somewhere near Khar Us lake’s shore

 

After crossing the barren plateau between the basins of Khar Us and Khyargas lakes we approached the target, deviating from the Zavkhan road using the GPS (around 130-140 km’s from Khovd). The weather is excellent on the salt flats: sunny, cold and no wind. I am in time to explore a little and raise my tent before sunset

 

This nice lake was my biggest hope to found unfrozen brine with decent size, but now it was covered by a thick slush layer. I know this jewel from previous trips and saw it unfrozen at -23 degrees Celsius (!). Now the slush is above -20, maybe the last snowy days diluted a little the surface layer’s composition

 

A little farther I observed a smaller pond, which was only partially covered, with the salt formations on the bottom visible. This is what I am looking for. The temperature of the uppermost layer is below -20. Great

 

I found a good place for the tent on a slightly convex portion. For my surprise I can even secure it as the salty ground was just perfect (not too soft, not too hard) at these low temperatures

 

Just before sunset, after only a few minutes walk from my tent: What the heck is this? Oh yeah, it’s unfrozen!

 

And it’s VERY deep! At least 1.5, but rather 2 meters! Astonished to found this outstanding water body here. A really pleasant gift for the end of the day. Hmmm… Yep, I can do it. I felt huge amounts of dopamine invading my body

 

On the surface it was around -20 degrees Celsius, but for my big surprise the sensor set on the bottom showed +1.8 degrees! As outside air temperature was below -25, this is really weird. I don’t believe, that the solar radiation can cause this, it’s more likely caused by a strong spring under the salt bed. I will let the sensor here during the night to observe the fluctuation. Unfortunately this logger is said to work only above -30 degrees, so I have little chances to monitor the entire night. Certainly will be below -35

 

As I expected, a very cold night was waiting for me. One of the coldest I ever spent in tent. You need to be prepared here, no chances to survive without the proper equipment

 

This is outside near surface temperature beside the tent. I haven’t observed the conversion to Fahrenheit scale as at -40 the two are exactly the same. Probably I pressed some combinations of buttons, which caused this change

 

During the severely cold night even this special lake froze. Except for a small portion near the steepest side, the brine pond was covered with a thin crust (around 0.5 cm) of salty ice. Bad news for me: looks like my big plan can’t be realized… Then again, despite the extreme conditions the logger was constantly recording. The bottom of the pond cooled only very little from yesterday afternoon as the device showed +1.2 degrees in the morning

 

Even though, I have a lot to do here as the entire ecosystem is extraordinary. This dark colored salt crust can melt the snow cover even below -30 degrees. No other dry surface is capable of this

 

This matte-white substance is completely frozen brine, an eutectic mixture of pure salt and ice. Very shallow ponds can reach this state during exceptionally cold nights, like the previous one

 

A quite dangerous place to walk around as sometimes the salt crust is very thin and it can break under your weight

 

Measuring the temperature of a pond. Meanwhile I realized the Celsius to Fahrenheit scale change, but (as I never done it before) couldn’t figure out the button combination necessary for this action and left it like this. As a matter of fact my purpose was to explore/ monitor liquids with negative temperatures not only in Celsius (which can be attained even in the case of sea water), but also in Fahrenheit scale, which means below -17.8 degrees Celsius. Therefore this unexpected joke of the fate wasn’t really a problem for me

 

In many parts the salty surface reminds me of the spiky skin of the moloch, a weird australian reptile

 

There are also very tiny ponds, like small holes in the salt crust

 

Around noon I found the big pond unfrozen again. Even if the air temperature didn’t rise above -30 degrees, under the midday sun the hard crust of the morning has transformed into a thin layer of slush. No words. It’s dream-like. After all I can do The Dive (details in part 1). Note: This picture was made by the “self-timer/10 seconds” function of the camera, using the tripod

 

After the experiment: the equipment on the lake’s shore

 

The unperturbed midday sun and complete calm helped me to accomplish this performance safe at -30 degrees air temperature

 

Standing on the place from where I’ve done the plunge

 

Mission complete. Time to leave, the driver will come after me soon

 

The Seeriyn Nuuryn Ulaan range in the distance

 

This part is a little saggy. Not dangerous, but you can’t cross it without mocking your boots

 

Camels grazing not far from the salt flats. I saw them every year in this grassy area

 

Some smaller dunes

 

Still no wind, hence I feel comfortable moderately clad below -25 degrees. But the hoarfrost don’t lie

 

The driver is punctual

 

Ganbold and his UAZ. This russian 4wd car is still common in Western Mongolia, but in the central and eastern part of the country the new korean and japanese jeeps have mostly displaced them. However the driver told me that those are not really good in the winter as diesel fuel is more sensitive to the extreme cold

 

Following our track on the way back to the road

 

This is the “main road” between Khovd town and Zavkhan sum. We haven’t seen a single car for about two hours

 

He is an experienced driver, which is a must in this harsh wilderness. Mongolian drivers are also good mechanics. The two profession is one single here. You must be able to repair your car if needed as localities/ car services are very far from each other

 

The final section on the new chinese-built asphalt road

 

Two days later I visited Khovd museum. Snow leopard skin and ibex. The former prey on the latter

 

Ibex and argali (Marco Polo sheep) horns. Both animals are very large and robust, considerable bigger than their european cousins

 

Stone heads of turkic origin. Before the mongols this region was ruled by turkic tribes. Kazakhs are also part of them and in the Altai mountains (especially in Bayan Ölgiy province) they are still the majority

 

Some war related artifacts

 

More mongolian ethnic groups are living in Khovd province. Each one has his own specific clothing

 

The brown ones are kazakh

 

Religious artifacts. Buddhism is the dominant religion of the country

 

After two days rest in Khovd we start the trip to the Altai Mountains, my second target. Herds of mixed sheep & goat are very common in Mongolia

 

Crossing Khashaat pass (2550 meters) on the border of Khovd and Bayan Ölgiy provinces. From now on we are on kazakh land

 

Tsast Uul (around 4200 meters) the highest peak of the Tsambagarav range is in front of us. Now we are heading to visit a kazakh family who are hunting with eagles, but tomorrow I will return to the mountain

 

Nice weather and is likely to be the same in the following days. The previous night was cloudy, the ground is covered with a thin layer of fresh snow

 

Yeah, this is the road…

 

Lonely tree near a frozen river. There were no others even in the bigger surroundings

 

This can happen here at any time, but Ganbold knows his profession

 

Meanwhile the mighty Tsast Uul is watching us

 

Approaching Altantsögts, the village where the “eagle family” lives

 

And here we are

 

After lunch we are heading to the nearby hills to hunt with the eagle. My host is the multiple national champion of the “eagle festival” held every year in Ulaanbaatar and also in other locations outside Mongolia

 

“Kran” is the kazakh name for eagle. They are trained to hunt foxes, rabbits, even wolves. This is an important local tradition

 

“Hmmm, what can I eat here? I can see only sheeps and goats…”

 

We move to another location. The master’s son is handling the big bird

 

I observe on a neighboring ledge another “eagle man” on horseback

 

“I’m too hungry, can’t wait more. I will eat this rival!”

 

Nope. We are friends and will continue the hunt together

 

As no wild meet is available, we are playing with what we have

 

Ganbold is not big a fan of hiking. At least not by foot 😉

 

No rabbits, but still wonderful here

 

Tsast Uul in the distance. We will meet tomorrow

 

For a lil’ while I became a kazakh. Or it’s maybe more? Many people say hungarians are related to kazakhs

 

The champion with his honours

 

Kran serving dinner. Our meal was also lots of meat, traditional kazakh style. They eat even the eye of the sheep (I admit I skipped that one). No place for vegans here

 

Next morning we start the way to the mountain

 

The night was starry, but now the clouds are invading the sky. The top of Tsambagarav is covered by altocumulus lenticularis

 

Stopping/ eating in an isolated mongol yurt. As I understood, kazakh yurts are bigger, hence more difficult to keep it warm during winters. Therefore kazakhs are living in houses in the cold season

 

This doesn’t looks very good. The forecast showed only partially cloudy for today

 

We reached close to 2500 meters elevation and soon I started the ascent. It’s noon now. My plan for today is to set my camp a little higher and do an acclimatization trip to 3000-3500 meters

 

The tent was raised at 2700 meters elevation. It wasn’t easy. No strong wind, but those frozen rocks…

 

The weather worsened as I climbed higher. The wind intensified and snow started to fall. Anyhow I reached above 3500 meters, that’s enough for today

 

Back to the camp. In the late afternoon the weather conditions improved and the night was completely starry. It was much more comfortable in the tent than at Sangiyn Dalai as it was about 10 degrees warmer. So I rested pretty well

 

As I expected (and hoped) the next morning the weather was good. I started the climb in dark. Temperatures in the -20s, but the windchill was quite strong. On the surface certainly was colder as my feet felt it soon. On the mountain, because of the steep terrain you are more predisposed to frostbites as the contact with the solid surface is much longer than when you walk on flat terrain. Altitude also worsens this

 

Nice sunrise, but not (yet) for me. Since I climb from the west I am in the shadow of the mountain

 

Reaching a flatter portion above 3600 meters elevation. Now I can see what is waiting for me in the final part. More than I thought

 

Traversing an exposed, edgy section with some easy technical parts. No need for the crampons until now. The snow is small and has good consistence, the wind is mild to moderate

 

Finally, somewhere above 3800 meters the Sun found me. Or I found him. I climbed constantly for more than 3 hours, it’s time to eat something. That something is goji berries & pecan nuts

 

The steep rocky part soon is over. I feel the altitude. No sickness, but I’m sluggish

 

Definitely crampons time. At around 4000 meters

 

After 5 hours of strenuous effort from the camp I reached the top of Tsast Uul. The GPS shows between 4200-4210 meters. On the maps usually appears with 4193 m, so it’s pretty close. Ganbold told me no climbers are going to Tsambagarav in the winter, not even mongolians. Instead in the summer many, including westerners

 

Looking to the east (towards Khovd)

 

The top is very flat, more like a plateau

 

A zoom to the west: many other high peaks of the Mongol Altai

 

Now it’s almost noon, the temperature (still in Fahrenheit) is only slightly colder than my bath in Zavkhan sum (-22.3 in Celsius). Of course this is not a correct measurement, but when it’s windy solar radiation has little effect on the sensor

 

The steep slope of the glacier

 

There are some hidden crevasses under the snow on the ice cap. This hole was made by me, involuntary of course. Fortunately I had the luck and strength to pull myself out before disappearing completely. The driver told me that Khüiten Uul’s Potanin glacier is extremely dangerous because of these formations and according to his knowledge it was a single mongolian climber who reached the top of the 4374 meters peak (highest in Mongolia) in the winter, but he died on the descent

 

I will follow the same way back. When it’s steep on the ice is safer to step backwards

 

It’s warmer and the wind is light. The hard part is over. I forgot a thermos somewhere during the ascent, but I will recover it following my trails. Otherwise soon it will be tough for my kidneys…

 

On the last part the weather became really warm as the wind stopped completely and the early afternoon sun was doing his best. At a certain time I felt comfortable in a single blouse. Incredible how much difference between the windy morning and this abundance of radiation. Only rocks. Pretty tiring as the snow is small and your feet are constantly unstable on the steep slope

 

I saw the driver’s car coming while descending the mountain. He arrived much sooner this time, maybe he was a little worried. I packed everything in time (also have found the lost thermos) and started the last, easy part back to the meeting point

 

I’m okay, he’s okay, Khovd is waiting for us

 

It was my pleasure

 

Because of the snow drifts we must found another way through the rocks. It was on the limits, the car almost crashed at a certain point. Thanks to the drivers experience we managed to get out from the labyrinth

 

Last view of Tsambagarav. Or maybe not?

 

Back to the asphalt we stopped to eat beside the road, then helped another guy to start his frozen diesel engine. Here people always help each other as they know very well what it means to be blocked in the middle of nowhere

 

My hotel room in Khovd. See the picture? Its Tsambagarav

 

Giant mongolian boot (gutul) in the center of the town. Its match is on the other side of the road

 

Next day I go to a hike to Ulaan Uul sandstone mountain in the vicinity of the town. Frosty morning in Khovd. And back to Celsius  🙂

 

He has the teeth, I have the ice axe. But the contact remained only verbal

 

Ulaan Uul at sunrise

 

It’s colder than on the mountain. But without the windchill is not that bad

 

After about 10 km’s on the road I turned to the right and started to climb the mountain from the back side. Because of the new snow layer now is dangerous to try the rocky front side

 

Following goat trails between the sandstone boulders

 

On the top is much warmer and there is still no wind. The thermal inversion is very strong

 

Khökh Seeriyn mountains, another 4000er

 

Khovd in the mist. You can see the runway beside

 

And…Tsambagarav. Again

 

Descending on the same side. From the road I hitchhiked and reached the town by car. The traffic is rare, but the few cars will certainly stop for you. Often without waving

 

Restaurant in Khovd. Today is Sunday, many of them is closed, including this one. I can’t order my favorite soup…

 

Next day I have the flight back to UB

 

Approaching Ulaanbaatar. This winter is completely free of snow in the capital

 

With my buddy 🙂

 

The Government Palace on the Chinggis Square

 

The Giant Buddha statue of the Gandan monastery

 

Turquoise reflections on the streets of Ulaanbaatar. It’s almost spring here

 

Stone caravan on the way to the airport. I will certainly return here

 

To be continued…

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Liquid frost: the hyper-cold brine ponds of Sangiyn Dalai (1/3)

Intro: Freezing-point depression

This chapter will be a little different than the “classic exiles” as the research’s main target will be not air, but water and beside this the writing has a separate personal/ philosophical section. However the plan is strongly related to the local climate’s peculiarities, therefore worthy to include here as a new episode.

We know that water freezes at 0 degrees Celsius. In a practical approach a mixture of ice and water has always this same temperature, not influenced by the elevation (atmospheric pressure) as in the case of the water’s boiling point, which can decrease very much in the high mountains. This is valid for pure H2O, but if we dissolve some substances in the water (especially salts) the freezing point will start to decrease.

In the case of NaCl (rock salt) at maximum concentration (23.3%) this can go as low as -21.1 degrees Celsius. There are a few other salts (MgCl, CaCl), which can decrease the freezing point even farther. This is lab science, but how about nature?

 

The relation between the temperature and the salt content in the case of NaCl solution

Sea water contains around 3.5% salt and freezes at -2 degrees Celsius. The Arctic and Antarctic waters have this temperature under the ice. Are somewhere on the planet conditions so extreme to cool liquids to temperatures much lower than this?

 

Choosing the target

As you can conclude there are two terms, which are crucial here: 1. extremely salty water (brine), 2. severe cold. The combination of these two is mandatory.

Regarding nature/ climate, the first premise is mostly related to aridity, where the lack of rainfall and the strong evaporation will increase the salt content of the water bodies situated on the bottom of the closed basins and the second premise is about persistent seasonal cold, when these concentrated fluids are exposed to very low temperatures for a long time. Something like a crossing between the Dead Sea and Siberia? That’s right.

After a thorough pondering I’ve concluded that outside of Antarctica’s Dry Valleys (where this kind of environment has already been studied: https://en.wikipedia.org/wiki/Don_Juan_Pond), north-western Mongolia offer the best conditions for this phenomenon to happen.

 

 

Here are places which receive rainfall so low as Death Valley in the US, while at the same time have average winter temperatures similar with Central Siberia. Zavkhan sum of Uvs aimag is a good example for this combination of extremes, where the mean yearly precipitation is around 50-60 mm and the average January temperature is under -28 degrees Celsius.

Beside this, winter is the dry season, therefore snowfalls are quite rare and inconsistent here, with January and February averages under 1 mm and the snow thickness of the midwinter is usually between 0-5 cm. Locals refer to 4-5 cm as “big snow”.

 

 

Because of its dry climate the Great Lakes Basin of Western Mongolia has many salt lakes/ flats, which due to the higher mineral content, in the winter-time can cool down to much lower temperatures than the sea-water before freezing.

I chose the salt pan of Sangiyn Dalai lake in southern Uvs aimag (situated around 1030 meters above the sea level) to be my research area for this new purpose, where I suppose to have excellent chances to found liquids in natural context at extremely low temperatures.

 

The location of the Sangiyn Dalai salt pan on the map of Mongolia (red dot)

Brief summary of the research

I reached the salt flats on 9th of February and set my camp on its surface in the afternoon. I know this area for some time (I’ve been here more times in the past winters) and with the help of a detailed satellite image and GPS I identified many small and medium sized brine ponds/ lakes (1-20 meters in diameter) which can remain unfrozen at air temperatures lower than -30 degrees Celsius.

 

Satellite view of the lake and salt flats (brown part on the western shores)

This season is an average one, but now became colder as the daily maximum remained below -25 degrees and were good chances to have a night minimum of around -40. The sky is clear, the air is still. The typical thermal inversion of the mongolian winter. The snow cover in the area is around 3-4 cm thick and is only partial on the salty surface.

 

My tent in the salt desert

The particular lake I hoped to found unfrozen had now a layer of salty slush on its surface, hence the bottom pattern was not visible. The liquid’s temperature was close, but not below -20 degrees. Not far away I found a smaller one, which was only partially covered and was colder (below -20 near the surface).

Shortly after the tent was raised I discovered another lake, which was between the few still unfrozen water bodies seen by me on this day. But this one was more impressive than the others as it was significantly bigger (around 8-10 meters long) and surprisingly deep (around 2 meters) for its size.

 

The newly discovered unfrozen brine lake

The uppermost layer had a stunning temperature of -21, -22 degrees Celsius, but for my great amazement at the bottom it was above 0 degrees (+1.8 to be precise). This “warm” bottom cooled only very little even after the frosty -40 degrees night, the device shoved +1.2 degrees Celsius.

While there was a thin crust of salty ice on the surface of the lake, a small portion near the steepest side remained unfrozen. I concluded that this strange phenomenon must be caused by a strong spring under the salt bed.

 

Measuring the temperature of another pond . This is Fahrenheit scale, in Celsius it means -24.5 degrees

Even if the air temperature did not rise above -30 degrees Celsius, at midday the solid crust had transformed to a pasty slush. I collected half liters of brine from this lake with the purpose to found out the exact composition of the minerals (and maybe microorganisms) in the solution after returning home.

 

The coldest dive

As a “cold fanatic” I had a big dream for a long while, when I accidentally discovered the hyper-cold solutions near a former bay of Uvs lake: having the coldest bath ever taken by a human. This wish later transformed to “performing the coldest dive” as an even more complete form of the previous. And I want to do this unsupported, alone in the wilderness. After many years of planning, struggle and bad luck related to injuries and improper climatic conditions, on 10th of February 2019 shortly after midday the time has come.

 

After a -40 degree night even this special lake froze

This newly discovered lake has the size & shape ideal for my plan and the actual conditions were just on the limits of the coldest possible as most of the water body had some thin slush on its surface. I am here, physically, logistically and mentally prepared. Let’s do it.
I call this “The Convergence”.

After relocating the tent close to the lake’s shore and sorting everything to help me in this action, at 1:30 PM I was ready. Shorts, scuba gloves & socks, swimming goggles & cap. Just the minimal protection for this extreme environment. Most of my body will be in direct contact with the hyper-cold fluid. The temperature of the uppermost layer represented by the salty slush was around -22 degrees Celsius.

You have VERY short time here, no fumbling or bad calculation will be excused. The body looses heat 25-30 times faster in water than in air and at these freezing temperatures the solution can cause you frostbites in less than 30 seconds (!), much sooner than hypothermia can install, even before hyperventilation is over. And this is valid for any part of exposed skin. Frostbite is by far the biggest risk here. I know very well what this medium is capable of as it is not the first time I expose myself to these elements.

 

Traversing the hyper-cold lake

The dive went smooth. Good adherence on the margin, haven’t touched the bottom or the side with any body part, no brine entered inside the goggles and I managed to get out of the water in less than 15 (maybe 10) seconds.

 

Close-up of the thermometer: -7.3 degrees in Fahrenheit means -21.8 in Celsius (the sensor inside the brine slush)

Because of the speed I haven’t seen almost anything while underwater, reaching/ grabbing the other side and pulling my body out of this natural rapid-freezer in a single flow-like movement. The coldest sensation was just when I emerged/ left the water as then my entire body passed through the -20 degrees brine-slush layer. Probable the fastest cooling rate a human ever experienced.

 

The equipment used in the experiment

After out from the lake I knew the real danger was over. The tent was waiting for me with the strong greenhouse effect inside. The temperature difference between exterior and interior was certainly above 20 degrees Celsius in this part of the day.

I guess many people will think it’s still very dangerous when you are out wet at -30 degrees, but I can tell you from this and previous similar experiences that during midday sun and complete calm, for a few minutes you are safe, it’s almost “comfortable”. Of course, this feeling is enhanced by the adrenaline and endorphine rushes, preceded by massive dopamine ammounts and followed/ topped by serotonin release. A complex and thick biochemical cocktail. Genuine catharsis.

 

Mission complete

The instruments used in the field

-One LogTag Tred30-7R data logger with the measuring range between -40 and +99 degrees Celsius, an accuracy of 0.5 degrees Celsius and a resolution of 0.1 degrees Celsius.
-One Greisinger GMH 2710-T digital precision thermometer with the measuring range between -199.9, +200 degrees Celsius, an accuracy of +-0.1 degrees Celsius and a resolution of 0.1 degrees Celsius.

 

The LogTag data logger measuring the bottom temperature of the brine pond

To be continued…

 

 

 

 

Aguita Brava volcano: Mars on Earth (3/3)

Interpretation of the logger’s graph

 

The temperature curve of the 7 day research period. I configured the device at home in Romania. Take therefore away 7 hours from the graph’s time to reach the bolivian local time. The 15:21 starting value means 8:21 AM

As I found the tripod with the instruments fallen over and partially buried under the snow on June 27, I had to found out when this happened. Analyzing the graph I noticed a remarkably elevated maximum temperature of 16.8 degrees Celsius in the early afternoon of June 22. That’s definitively an impossible value at these altitudes. The certitude regarding this conclusion is confirmed by the extreme fluctuation what happened shortly afterwards, when in a matter of a single hour the temperature dropped more than 14 degrees than rised again more than 10 degrees.

This would certainly not happen if the sensor was properly sheltered in the radiation shield. Here the sensor was over-exposed and the extreme temperature change must be caused by alternating windy and calm periods. So the fall over happened before. But when?

Closer view of the unrealistic high with the following dubious fluctuations (zoom in the image)

The first two days (when I was present in the region) are excluded. At the time the weather was fine, without even moderate wind. The temperature curve of this period is also realistic. Going a little ahead the things started to make sense. In the night of 21-22 the temperature was suspiciously high and constant (between -1 and -5 degrees). This can happen here only during very cloudy or windy weather (or both). And in the next day was the dubious 16.8 degrees maximum. Puzzle solved.
On the other hand in the last 4 days the maximums didn’t climbed above 0 degrees. This is probably because the sensor became snow covered. As the minimums of these days are quite low (approaching -20 degrees) and the temperature curves are looking regular I suppose the weather was again clear and not very windy (at least in the night).

After this short detective work let’s go back to the scientific evaluation. We have only 2 days to take in consideration as having valid datas:

June 20: This first day was the luckiest with both the lowest (-26.6 degrees Celsius) and highest (4.0 degrees Celsius) temperatures, respectively the biggest daily thermal amplitude (30.6 degrees).

The curve of the first day with the sharpest temperature rise (take away 7 hours to reach the bolivian local time)

During this interval happened a temperature rise of 12.7 degrees in 60 minutes and 6.7 degrees in 15 minutes.
Even if the weather station started its activity more than an hour after the astronomical sunrise, because the crater’s bottom was still in shade the inversion wasn’t affected before the sun reached the lowest elevations. This fact can be clearly seen in the graph, where the temperature remains almost uncheanched between 8:21 and 8:51. The minimum was registered at 8:36 AM.

The datas from the first hour of observation (take away 7 hours to reach the bolivian local time)

Then the temperature started to rise very fast and in less than 3 hours and a half climbed to +4 degrees, the maximum of the day. What’s interesting this happened pretty soon, just after midday. In the early afternoon the curve became close to an isotherma, remaining mainly around 2-2.5 degrees Celsius. In the latter part of the afternoon the temperature started to plummet and the vigorous fall continued during the evening hours. I was not present in the crater in this warmest period, but the extreme temperature rise was obvious also outside. It was absolutely no wind even at noon. A light breeze started after 1 PM. This explains why the maximum was registered at 12:16 PM.

June 21: The temperature dropped to -22.1 degrees Celsius in the morning at 7:46 AM. The sharp rise started again just before 9 AM and continued to the noon when reached 3.7 degrees, the days maximum. You can observe an outstanding upward curve during the first part of the night when the temperature rised from -16 to -5 degrees before starting to plummet again. It means even light winds can seriously disturb the night inversions in the basin. The amplitude for this day is 25.8 degrees, quite big, but significantly less than the first days’s 30.6 degrees. The night was clear again, but sometimes I noticed a light breeze at my camp (the same place, around 6 km’s from the crater). The near surface temperature was also less low than in the first night (more than 5 degrees milder). There were some cirrus clouds in the morning. I was present in the surroundings to around 3 PM and the weather was comparable with the day before: sunny, calm or light winds and quite warm for these elevations.

General conclusions

-If the weather is clear and calm the inversion layer in the crater is thick (filling completely the endorheic basin).
-During ideal conditions the lowest temperatures occur around 8-8:30 AM. The inversion is destroyed only well after the astronomical sunrise, when the sun reaches the bottom of the caldera.
-When is partial snow cover the head level air temperature above the snowy part is much closer to the ground level temperature above the uncovered part than to the snow surface temperature just below. The minimum temperatures above the snow surface are much lower than in the air above (up to 8-9 degrees difference).

-Because the first air movements usually start after midday the maximums are registered around noon when the heating of the ground is at peak levels.
-Clear skies are prevalent in the area during winter, but the calm conditions are much rarer. Strong winds (mainly westerly) blow often even at the crater’s bottom.
-The nights and mornings have more calm periods, the afternoon beeing the windiest part of the day.
-During windy weather the night minimums are significantly warmer (up to 20 degrees Celsius).
-The cooling period has a much longer curve than the warming period. The steepest parts of the graph are the ones just after the sun reaches the depression’s bottom, but it continues quite abrupt to the noon without major changes.
-The daily thermal amplitude can exceed 30 degrees, producing probably one of the biggest fluctuations in the entire world. *
-The minimums can go down well below -25 degrees (very likely also below -30 in certain conditions), lower than the current bolivian national record (-31 degrees Celsius) and maybe than any other official temperature measured between the tropics.

*The actual world record for the highest amplitude in 24 hours is more than 55 degrees Celsius and it was observed in Browning, Montana-USA. However this is a completely different kind of temperature change as the big difference was caused by a sudden change in the weather conditions and not by the pure physical potential of the local air.

 

Comparing my results with the local and global statistics

After the return to La Paz I visited the National Meteorological & Hydrological Service of Bolivia. There I found out some important datas:
-The lowest official temperature ever measured in a bolivian settlement is -25.7 degrees and it was registered in Uyuni (around 3700 meters elevation).
-The lowest official temperature ever measured in Bolivia is -31 degrees and it was registered at Laguna Colorada Weather Station in May 1992, close to the lake with the same name (around 4300 meters elevation).

The chart with the lunar/ annual minimums recorded at Laguna Colorada

-On 20 June 2018, when my logger recorded -26.6 in the crater of Aguita Brava volcano the minimum temperature in Uyuni was -9.4 degrees Celsius. Unfortunately they have no infos about Laguna Colorada for the same day. They only sometimes get datas from there. My guess is when those -25.7 and -31 degrees happened it was continuous snow cover in both locations. The difference between a -9.4 and a -25.7 degrees is enormous and can’t be explained otherwise, taking in consideration the weather was constantly clear and even windless on 20 June 2018.

The minimum and maximum temperatures in South America on June 20, 2018 with Potosi (Bolivia) having the biggest thermal amplitude : 27.1 degrees Celsius: from -10.5 to 16.6 degrees Celsius (source: Ogimet)

In the period of my staying it was no snow cover in Uyuni nor in any other place in the country situated below 4000 meters and the satellite datas showed the immediate surroundings of Laguna Colorada it was also free of snow. Definitely out of question to go even close to -31 degrees under these circumstances. During my visit the caldera was only partially snow covered and still went down to -26.6 degrees Celsius and close to the snow surface even much lower (-35 degrees). Interestingly the temperature close to the uncovered surface was about the same as the air at head level above the snow. I have no doubt if the same atmospheric conditions are present and there is continuous snow cover in the crater the minimum would go well below -30 degrees, surpassing the lowest official bolivian temperature.

 

Coldest place between the tropics?

To my knowledge beside Laguna Colorada there is a single place situated on tropical latitudes where the temperature plummeted below -30 degrees. It’s Ollagüe in Chile with -37 degrees Celsius. This is the lowest temperature measured between the tropics what I found on the net. Ollagüe settlement is situated right on the border with Bolivia, but it is also a high volcano named Ollagüe nearby. The village’s elevation is similar with Uyuni’s and much lower than Laguna Colorada’s, so a -37 degrees there is a little dubious for me. Maybe it was registered somewhere on the volcano? Is this data reliable at all? Maybe it was only -27? It looks much more realistic for a place situated at 3700 meters elevation at these latitudes. However, until solid facts reveal the truth this remains an open question.

In my opinion the crater of Aguita Brava is a strong canditate for both the titles “the tropical pole of cold” and “the pole of diurnal thermal amplitudes”.

 

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