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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Aguita Brava volcano: Mars on Earth (2/3)

                      Journey photo album

 

Rough start with one full day delay. At Miami airport

 

My hotel room in La Paz . Pretty cool, but clean and has good hot shower

 

Basilica of San Francisco, one of the most emblematic buildings of the capital (16th century)

 

The center

 

Visiting Tiwanaku pre-columbian archeological site the next day: The “Gate of the Sun”

 

Another famous statue of the religious complex

 

It’s easy to make new friends here  🙂

 

Huayna Potosi (6088 m) seen from the road back to El Alto

 

Descending to the city center with an aerial cable car (the cheapest and fastest method)

 

La Paz: Crowded traffic with lots of street vendors on both sides

 

Arriving in Uyuni (hostel)

 

Starting from Uyuni with a private driver to the south-western alpine desert, where my target is located. There are daily flights from the capital. Uyuni is a prosperous touristic center, all because of the nearby Salar de Uyuni, the biggest salt flat in the world (more than 10.000 square km’s, over 140 km’s in diameter)

 

San Cristobal silver mine

 

Villa Alota village

 

Climbing higher and higher. I start to feel dizzy

 

At over 4600 meters it is obvious: I’m not well acclimated…

 

Snowy peaks on the chilean border

 

Approaching the Eduardo Avaroa National Park. You need to buy an entrance fee here

 

Straight towards my target

 

The final part became more wintry, but still manageable without any technical difficulties. We are approaching 4900 meters elevation

 

I start the journey by foot around 1:30 PM from near the fumaroles and hot muds of the Sol de Manana complex. Some tourists are present at the bigger geysers. The weather is quite windy and felt much colder than at the lower elevations

 

First time above 5000 meters. I’m in good shape but the backpack feels heavy at these altitudes. The breathing is difficult. From here I can see Aguita Brava volcano in front of me

 

Tired, around 5 PM I set my camp on the barren plateau. No tent, only a bivy sack and a good sleeping bag. My survival strategy is to shelter from the westerly winds behind a big boulder

 

Below -20 degrees on the ground beside me. The night is clear and surprisingly even windless. The Milky Way looks completely different from these heights. It is more similar to the nebulas seen on Discovery or National Geographic. After some hours of strong headache and nausea I start to feel better and decide to climb the mountain in the dark to reach the crater’s bottom before sunrise. I leave the unnecesary things here, securing the bivy sack with nearby rocks and at 4 AM I’m heading to the volcano

 

The main peak was farther than I thought. The sunrise found me struggling on the ridge. But the view is awesome!

 

Finally at 5500 meters on the top of Aguita Brava. No wind even here, I feel very lucky

 

First view of the crater. The lowest part still in shade. What? A lake? I didn’t expected this. The place is completely dry on GoogleEarth

 

While descending in the caldera I suddenly feel how the cold is intensifying. It means the inversion layer is thick, filling the entire endorheic part of the basin. Okay, it’s no water nor ice at the bottom, only a dry lakebed. But a strange thin mist was present on the lowermost layer. Probably this tricked me. First I thought it is something related to the volcanic activity like the fumaroles at Sol de Manana

 

I do a quick near surface measurement with the electronic precision device. Wow! That’s really impressive for a tropical latitude!

 

The alcohol thermometer shows even lower values. It seems I’m not late. Here the night is not over. The mist must be caused by the strong inversion. I know the air is extremely dry on the Altiplano in the wintertime, but here on the bottom, close to the ground probably contains much more water vapour

 

In a couple of minutes the weather station started its activity. The snow mound is where I buried the logger to protect it from the extreme cold. The sensor can measure down to -40 degrees, but the logger itself is functional only to -30

 

It was difficult. But the project is on track

 

As the sun reached the lowest parts, after only a couple of minutes became considerable warmer in the crater

 

My self-designed talisman at the bottom of Aguita Brava caldera

 

Juriques volcano (5704 m) in the background

 

Putana (5890 m), the smoking volcano (sulphur dioxide) is another major peak on the chilean border

 

The plant living at the highest altitudes (around 5200 meters)

 

At noon became surprisingly warm. Still no wind, my face is burning. As the water in the thermos is lessening I compensate the fluid loss by eating small ammounts of snow. Dehydration is a serious danger at high altitudes

 

Around 2 PM, back to the camp. The other thermos waits for me here

 

Exhausted but very content. I go to sleep early today

 

Next morning. Doesn’t slept much, but the long rest was certainly helping

 

Approaching Sol de Manana geysers

 

Nobody is here now, I can enjoy the nature’s spectacle in solitude

 

Primordial landscape. The battle between cold and heat

 

After reaching the main road, I was waiting for the trucks which are coming from the Apacheta mine. Non of them appeared, but I had luck with a jeep coming from the geysers

 

At Polques hot springs. The driver will take some tourists to the border than he will pick me up here and we will reach Uyuni in the evening

 

Local bird hunting in the shallow water

 

Laguna Chalviri (around 4400 meters elevation)

 

Yeah, here the winter UV is stronger than at home the summer version. By the way: today I’m turning 40…

 

Uturunku, the highest peak in southern Bolivia. On the way back to Uyuni

 

Two days later I take a local bus (very cheap) to cross the famous Salar de Uyuni. Close to the shore is puddly, but after that is only dry salt pan as far as you can see

 

Short stop at Incahuasi island in the middle of the salar

 

The bus has elevated bottom, probably to can handle the puddles close to the shore

 

Almost 150 km’s of pure whiteness. We are heading to Llica settlement on the other side of the salar

 

From the village (background) I will go to a lesser known but very interesting geological structure: the Hoyada Ulo meteor crater

 

I had the crater’s coordinates on my GPS, but didn’t really know which way is the best. It ‘s around 7-8 km’s in straight line. Meanwhile the landscape became “western-like”

 

I reach the high plato around sunset. Feeling some presence of indian spirits I continue the hike until dark

 

Next day at dawn I’m on the rim of the crater. Surpisingly mild +1 degree Celsius here at head level.  (I know. This picture looks like a movie screenshot from the 60′ 🙂

 

But I measure -14 degrees on the bottom. Nice inversion.

 

A smaller salar. Partially frozen now

 

That’s water there. Very salty, therefore still liquid at these temperatures

 

After the sun appears the season changes to spring. I decide to climb to the highest ledge

 

Definitely worth the effort! Salar de Coipasa, another huge salt flat can be seen in the background

 

A condor is patrolling above his empire

 

The weird “viscacha” is like a hybrid between a marmot, a squirrel and a rabbit

 

No way. I must turn back. Meanwhile became quite warm

 

When returning I found llamas on the bottom. Very peaceful animals, like bolivian people in general. No need for shepherd dogs, as the bigger predators are rare on the Altiplano. Pumas are said to live “everywhere”, but the reality is they are in small numbers for the huge territory. Meanwhile the temperature climbed to +16 degrees. Remember the -14 from the morning? That means a 30 degrees daily amplitude!

 

Before complete dark I reach Llica. It was a long day. I think the coca leaves helped me 😉

 

Rising more than 1600 meters above the flat landscape, Volcan Tunupa (5321 m) is the biggest landmark in the middle of the salt desert. On the car back to Uyuni

 

The bus is creating waves on the waters close to the shoreline

 

Two days later I start the second (and last) trip to Aguita Brava. As now the full tourist circuit is open the approache is much cheaper. I travel with two french who are heading to Chile. I think french are the most common tourists in Bolivia

 

Reaching Villa Mar settlement in the late afternoon. After sleeping in the village we continue the journey to the high plateau the next morning

 

This snow wasn’t there the other day. Certainly the wind is responsible for this change. We must turn back a little to take the smaller road

 

Before 8 AM I leave the car. It is windy and the -8 degrees feels much colder. My plan is to climb the mountain today and descend to the other side tomorrow

 

The wind intensifies, the sun has no warming effect in these circumstances. It’s ironic how similar the pictures can be while representing completely different realities

 

In the first part I felt markedly stronger than the other time but above 5100 meters the walking/ breathing became harder and harder. The last 100-200 meters was a complete struggle. I thought after 2 weeks at 3500-4000 meters I can handle these heights without any problems. But it was far from truth. The 1400-1500 meter ascent in 7 hours was too much

 

I left the unnecessary luggage on the rim of the crater. The westerly wind was very strong here, blowing straight in my face while I started the descend into the caldera

 

Oh, no… After this extreme struggle I found the weather station on the bottom fallen over. I underestimated the local weather conditions trusting the crater’s “sheltering effect”. But the gales were present even here. Even now is present! Luckily non of the instruments were damaged and I managed to collect everything. I also checked the logger’s daily statistics and found out the best day was the first when the temperature climbed from -26.6 degrees to +4 degrees Celsius

 

The steep climb on the friable volcanic debris back to the rim was somehow less strenuous than I was expecting after the former difficulties. My guess is that after the organism is over the highest part and starts descending again it recovers (partially). Therefore a new climb will be less hard as you have already visited the former height before. I understand the logic and also knew the theory, but I’m surprized because of the contrasts and because of the short time you need for these changes. After packing full my backpack again I started to descend the mountain on the otherside

 

No real altitude sickness from now on, but I was definitely exhausted when reaching this boulder where I set the same kind of camp (around 5000 meters elevation). Now the protection has real meaning as the westerly is still blowing. It was a very hard day. Time to sleep

 

Next morning I’m heading to the Dali Desert, where the main road is passing. The night was alternately windy, with some calm intervals between. It was nice full moon and in a certain time the bright disk was positioned exactly above my head. I mean vertically

 

The surreal Cerro Amarillo (5661 m)

 

The wind became even stronger while I reached the road, but the lower elevation and higher sun angle takes away from the cold. After a new bath at Polques (where I met 2 other hungarians) a jeep taked me back to Uyuni. The same reasonable price again

 

The main plaza in Uyuni. The small town is a tourist magnet. There is little to see in the settlement itself, everything is about the salar. The small center area is crowded with hostels, tourism offices and restaurants

 

And of course: souvenir shops

 

Tours and tours and tours… Sharp contrast between the small, modest brick buildings and the big, colored buses and modern jeeps

 

Many street dogs, but they are all harmless. In Bolivia the quadrupeds are surprisingly gentle

 

Pique macho, a traditional bolivian dish. Not really a delicacy, but good when hungry. Or just to tease the many scandinavian feminists  😉

 

In the same evening I’m back to La Paz. The plane took off 20 minutes…earlier. Never seen such a thing in my life. I was very surprised how easy is to travel in Bolivia. Maybe too easy?

 

Plaza Murillo, one of the main meeting places of the capital

 

Mercado a Las Brujas (Witches Market), another tourist hotspot of the center area. Beside the many colored clothes and wallets you can found here all kinds of weird things like various medicinal plants and even dried llama fetuses

 

The next day I visit the National Weather Service’s office and found out some important infos (see in part 3)

 

As tomorrow in the morning I will start my journey back to Europe I will use this day to see more of the city. Heading down to the lower elevations

 

There are many cable car lines, all colored differently

 

The richer part of the city

 

In the afternoon I climbed a precipitous hill situated in the outskirts. It was quite difficult because of the friable rocks, also uncomfortable, as many cactuses grow on the steep sides

 

I have no time for the highest peak, the relief is too fragmented from this side

 

The high Andes at sunrise from the plane. Bye lack of oxygen!

 

To be continued…