HiLDA

You remember our plans on completing the Hilda baseline network to the nowthwest… ? – Yes, yes, Greenland.
Another year, another try – and this time with success!

Last Monday, Thomas and Konrad started again a trip to Greenland. This time, no Corona issues, perfect weather – and everything went smoothly and on time. After a great panoramic flight over nothwest Iceland and the Scoresby Sound, we finally make it to Ittoqqortoormiit, where we are greeted by Mette from Nanu Travel, who took care for our equipment through the Corona times.

While we had snow and rain in Iceland, Ittoqqortoormiit is still a winter wonderland. Meters of snow and ice, though the sun doesn’t set any longer. Temperature went up by 10 degrees since last week, so we are looking forward to comfortable consitions for setup – and plenty of woring time due to the Arctic day.

Next day we meet René and Hans from the radiosonde and telecom station up the hill, who will host our baseline measurement station for the time coming. After a short look around, we quickly decide for a suitable location and start unpacking our materials. Slowly, memories come back of the time two years ago – including the ones of all these undone things, as this station was the first one to be sent abroad. Unfinished mechanical works, an incompatible software system and non-existing remote control keep us busy for some days.

However, we have meanwhile gained a lot of experience, so it just takes time, until everything is done. Except for one thing: how to get the station online? It turns out that getting mobile data here for non-Greenlanders is close to impossible. After two days in search of possibilities, Mette saves us the day: we become commercial customers of the travel agency.
Now everything is in perfect order, so on Friday we switch on – and no more problems show up.
Konrad introduces our local caretakers in a great coffee-and-cake atmosphere to the sample handling procedures, so we can be confident that we will obtain interesting samples from this place.

Now, the Hilda network is at its maximum extension – alas, only for a few weeks.
Mýrar station will stop its operation after two years, as planned. When we finish the intensive observation period of this year in Iceland, we will take the first materials home again. Nevertheless, we have plenty of material to kep us busy in the lab for a long time!

It’s super windy! Well, not a big surprise as we are on Iceland. Nevertheless, it has an effect on our OPC-Tour as the beach part of the southbound tour is difficult to access. We definitely can feel abrasion by sand blasting – and our equipment shows some traces of wear as well.

Whereas we were able to reach the beach station, but unfortunately it was not possible to climb up Hjörleifshöfði. The station there is too exposed to the strong gusts. Of course we are curious to know how strong the guts up there were, but very unfortunately, the data recording has some gaps – possibly due to weather (we experienced that before and at other stations too). Nevertheless, winds above 20 m/s on beach level, and the station on Hjörleifshöfði is about 200m above.

While we were not able to climb up Hjörleifshöfði and got sandblasted while servicing the beach station, we spend some thoughts on the diversity of the particles flying through the air: There was sand and dust suspended in the air as well as drizzle and rain. Curious to see how the data will reflect this …

We know this will happen one day. One day, there will be so much water flowing down the sandur that we have to get off our shoes and wade through 4°C cold water in order to check the stations in the upper part of the Mýrdalssandur. But we did not expect to wade a 1km distance through 4°C cold water. Feet definitely feel differently after such a distance.

It was raining a lot during the last days, and we expected to see water here. And deep inside we hoped for the water to come and eventually bring fresh sediments to be eventually uplifted as dust (and measured by our OPCs). So here we are: Water is there and maybe there will be dust one day in future?

So, off the shoes and here we go! And so we did. The stations are located roughly some 1 to 1.5 km walk apart … and the water was covering almost the entire distance. Some minor dry patches in between, but not wide enough to get the feet warm again. Maybe rubber boots would be nice next time. However, the OPCs are now supplied with freshly charged battery packs! And hopefully we will measure more that drizzle … .

Our dust monitoring net work now consists of 15 individual stations that require our attention. Each location is chosen after a thorough discussion balancing science objectives (what do we learn) and servicing tasks (the battery needs to be changed every other day).

Eight stations monitor dust emission from the upper Mýrdalssandur, where water drainage systems fed by the glacier formed the landscape and deposited sediments ready to be blown away by wind. And in fact, further upstream water flows, further down stream, where – after last years experience – we installed the stations, dust was blowing.

Another seven stations were placed further to the south. First, to get an idea on something link a north-south transect assuming that the dust is blown towards the sea, and second, to investigate the spatial distribution of dust spots. Eventually, five stations were installed along the old N1, and one station on the sandy beach and one on the hilltop of Hjörleifshöfði. The brisk walk uphill every other day will keep us fit!

New year, new campaign – we promised to be back. The 2022 campaign will be much smaller than the one in 2021 without most of our cooperating colleagues. And, this time, it will be focused on southern Iceland. More precisely, on Mýrdalssandur, a place from which Thomas and Konrad had collected samples last year.

This year’s team are Kerstin, Luis, Thomas, Demetrius and Konrad, from TU Darmstadt and FU Berlin. And of course, our local cooperation partners from LBHÍ.

After settling down in Hrífunes, close to our measurement area, first exploration tours reveal – snow!, result of a very humid spring in Iceland. Luckily, the snow sheet is not a persistent problem, and after two days we can start with our setup, right when some dust emission occurs. Eventually, during the next days we install a network consisting of 15 stations in the most promising source regions, as well as covering the southern outflow towards the Ocean. As also the black beaches act as dust sources, we also monitor Hjörleifshöfði and the adjacent beach, where we encounter already blowing sand and dust.

Black clouds all over. The weather in Greenland stays rainy, snowy and stormy enough to delay our the flight day by day. We travel from Akureyri to Reykjavík and back in the evening, as the airline shifts the departure airport several times, trying to find a suitable slot for flying.
But at the end, we run out of time. As the weather forecast for the weekend is rainy again and we need to return latest by Monday, we have to pull the plug and cancel the trip to Greenland – again. Next year there will be hopefully another chance.

What is remaining now is packing all our things, picking up the last samples and returning home, while hoping that the weather will play along. Autumn has arrived in Iceland, too, and besides the colored landscape, snowy mountains become a usual sight.

A busy week lies behind Thomas and Konrad, travelling to major dust spots around South Iceland and collecting samples for the comparison with our main field site on Dyngjusandur. As these spots are not easily accessible, we cross rivers, swamps and travel many barely recognizable tracks. In particular the coastal sources of Landeyjarsandur and the estuaries of Kúðafljót and Skaftá are challenging, as they are partly under water after the heavy rain falls of the last weeks. And generally, they are not made accessible by roads. The GPS track must look like an ant track in search of food.
But in the end, by car and on foot we manage to collect 20 samples – all wet by now, but when dry, they will be of similar texture to our dust spot of the main field campaign – very promising.

So, everything done for the campaign. – – Oh wait, wasn’t there something missing, still from last year? – Yes, there was a baseline station shipped to some place and still waiting there – Greenland!
As the travel restrictions were lifted recently and we fulfill all the necessary Covid requirements, we decide that we should give it a try and spent the last week in Greenland for the setup. Everything starts quickly, flights are booked, tests arranged, and the poeple in Ittoqqortoormiit helpful in arranging the transport and lodging.
But of course, that seemed to work to smooth… And indeed, after a few days, Norland Air calls us back and informs that the airport in Greenland was closed due to rain damage. But they would be confident, that they would bring us there by another route or another day – let’s hope, that it is justified and we can successfully finish our task!

The last days of the campaign finally deliver what we were aiming at: different levels of dust concentrations, wind speed, and humidities. All relevant instruments are still working, so we are confident now that we will bring home a great data set – right until the end, when the last generator dies away, choked by an ultimate dust event with the highest concentrations of the campaign. A perfect ending…

The last days are split between dismounting and cleaning, packing the boxes and last calibrations, transferring the data home and sorting the tents into broken and reusable. And let’s not forget the social activities – the wardens and rangers invite all of us for a common dinner, a great evening out. In the same night, we get amazing northern lights as a parting gift – a perfect evening.

While most of the team is heading home now, Thomas and Konrad plan their trips for the next days. Soil sampling of the most interesting dust spots around Iceland is the task. Bad weather and worse roads may interfere, but hey, we are used to that meanwhile. And – another window may open for the HiLDA project, but this will be another story for another time…

The flooding ‘allows’ us to rethink our strategy – most instruments were carried from the measurement site to a safe storage. Some of them don’t make it back, as in case of the scintillometer, the realignment is too time-consuming. While thinking of the implementation on a new level – literally, as we have been delivered 30 cm of fresh sediment in two flooding days – a new challange creeps over the horizon: Wind.

20 m/s mean winds are predicted for several days. In the first night, we take the risk and leave the setup – our tent and equipment – unchanged, which turns out to be too optimistic. Later, we find readings up to 35 m/s in some of our stations on the mountain tops. Anyway, the tent is ripped, the poles of the wind fence broken – we need to think smaller and therefore reduce the setup to the basic experiment for a day. But as we are scientists and therefore curious, when the worst storms are over day be day another instrument finds its way back to the field site. Partly improvised, as different parts were damaged during the floods and storms.
Of course, also our sleeping tents were subject to to rearrangement – one actually took off for the next mountain (including sleeping bag and mattress), but decided 10 m above ground just to place it self outside the camping area. In view of flying pumice rocks, we decide to sleep behind strong walls – be it a car or a wooden hut.

But why fighting dust? – Well, as soon as the basin dries up, we get what we paid for – dust, more dust, way more dust – too much dust!
At 10,000 µg/m³ PM₁₀, the generators go on strike, and only the battery-run equipment survives. Lucky us, we can draw the ‘Ask Villi’-card, and after only four hours of blackout, we are provided with a working 5 kW generator from Möðrudalur for powering our field site. Yippie!
Our Hondas, having suffered dust and sand for a month now, get a treatment by the mechnic Svavar, but will be on spare from now on.

Another issue arising with the dust – well, except the impossibility to work during the daytime due to the ‘breathtaking experience’ – seems to be electricity. One by one, the digital inputs of our Rasperry Pis controlling our OPCs die away, and fastest in the places with the highest dust load. Luckily, this only affects the wind readings. But nevertheless, Konrad now checks on every service trip, whether the system has to be reprogrammed to a new input. That of course doesn’t make days shorter…

Our main site in Paradise is entirely flooded. Since two days, we do experience quite warm temperatures in the low twenties and strong southerly foehn winds blowing down from the glacier. Reason for this is the dance of a high and a low pressure system over the Atlantic Ocean south of Iceland. It generates a northwards air flow across central Iceland – statistically perfect wind conditions for dust emission! And a pressure constellation we are waiting for. However, this atmospheric circulation pattern comes with a ‘but’. Like a hairdryer, the wind increases the air temperature at the surface of the glacier, which in turn enhances the melting rates – sending a lot of water to our main measurement site.

We are prepared for having some water around at our main site occasionally. Up to a few centimeters depth, it’s not pleasant, but we can live with it – if it dries up quickly. But not with some 30 centimeter and a river running through the setup. That’s way too much water for the instruments, which are supposed to measure parameters like turbulence and hopping sand grains.

Luckily, we see the water coming. Since the early afternoon, it is arriving in the terminal lake area. Slowly but persistently. Earlier during the day than usual, which is suspicious and warns us that this time more water may arrive. At some point during the afternoon it becomes obvious that this time the flooding will be more pronounced than what we had experienced so far. Torn between the risk that the water level will reach the instruments, and the hope that it will magically stop increasing before, we eventually turn off all instruments and start dismounting the low-hanging ones. Just in time, as it turned out later. Early evening, we realize that even these instruments placed on two pallets (… water will never get that deep …) will get flooded if not removed. In a hurry, with all persons available – and in shorts – we carry all equipment to elevated ground. Hopefully being safe for the night …