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
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:

Sand surface measurement with the Greisinger precision thermometer

To be continued…