Author: Kerstin Schepanski

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!

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 …

We already spotted it during the first dusty days. There is another active dust source area on the other side of the river fed by the Dyngjujökull, our glacier next door. It seems to be the same sort of dust source as our Flæður, although slightly more active. A bit annoying, we admit.

Driven by curiosity how this source actually may look like, we decided to check it out today. The road up to Kverkfjöll is comparable easy to drive with a 4×4 and the landscape shaped by the volcanic eruptions is just impressive! The gravel road terminates at a parking lot close to the fringe of the glacier – just a few minutes walk away from the terminal ice where plenty of milky melt water drains out of the massive ice sheet ultimately forming river-like streams.

Is this the birth of the dust we see emitted further downstream? Still suspended in water causing its cloudy-milky colour at this point, though. But further downstream along the meandering banks, where the flow slows down, it will soon deposit a fresh layer of silt and clay ready to be uplifted into the air once it’s dry and windy.

So, where does this sediment load go? Will it form a dust source looks like the Flæður region? We are here to find out – but soon realize that the dusty places on this side of the river are too far off the road to be accessed by any means of transport that is available to us. In essence, what remains from this trip, is a gorgeous visit to the Dyngjujökull – and a glimpse at the place where the milky water starts its journey towards forming future dust sources …

Stórhöfði North is now up again after a long downtime due to repeated power failures – and it is running on green energy now! During the last few days, Konrad and Kerstin went south all around Iceland to Vestmannaeyjar to install a wind generator and a solar panel at our site. As it can be quite windy there, we had to wait for an as calm as possible day. Just the healthier option when working on the roof over a cliff… . Anyway, it was a calm day and we actually could put off a layer of clothing for some hours. And we should not forget to mention our very kind, respectful but curious neighbours: Puffins and sheep.

It should be like in a halfpipe: Dust source at the bottom, mountain ridges to the east and west, perfectly channeling dust transport in north-south direction.

Admitted, this sounds a bit too ideal to be real. We are curious to know how often and how much dust is leaving the dusty halfpipe of the Flæður towards the east or the west. Two days ago, we installed one of our mobile OPC stations on the roof of the mountain fringe. And today we stop by to transfer the first recording to our server – plenty of dust seen on the hill top!

We worked it out. The whiteish sediment layer is a superb reservoir for dust particles. The brownish serves as saltators. Perfect match, perfect dust source. In any case, the water resets everything.

We see the interplay between “turning into a dust source” and “becoming flooded” since we arrived in the Dyngjusandur area end of July. Nevertheless, during the last few days the surface area drying up and changing its colour from greyish-brownish to white is larger than the area which floods during the night. So, we are kind of expecting a shift towards turning the entire area into a dust source. That’s why we are here, that’s why we set up the tower in Paradise.

Our hope for more dust in the next few days is clearly not unfounded. Nevertheless, the flood surge arrived later this afternoon washing away the dusty spots that have formed during the last days. The good thing about this “not so welcome” flooding is that it will deposit more sediment on top, which will eventually turn into a dust source – if it once turns dry. Think positive!

Our OPC network aims at revealing new perception on the way dust travels through the atmosphere when leaving the Dyngjusandur source area. For how long and far will it remain airborne? During the last week, we set up 18 stations at locations which we hope will provide us information on when, where, and how much dust is suspended in the air. Some are located directly where we observed dust emission, some are mounted in a somewhat near distance to the source, and some are placed some tens of kilometres away.

Although our station network setup looks quite ok already, we have the subliminal feeling that one station is still missing. One, that will measure dust escaping the river channel in a direction perpendicular to the bounding escarpment. A behaviour we observe in particular during easterly winds.

Eventually, A few days ago, we found a nice place for an OPC monitoring this dust transport behavior and today on our tour to the stations in the upper and middle Flæður region we found a ridge around 60 metres above the river bed perfectly suited for measuring airborne dust leaving the river bed dust source region towards the west when the wind blows from the east. We are looking forward to climb up the hill again in two days in order to receive the first recordings!

Happy faces all around! Today is the third day in a row we see dust in the Dyngjusandur area. It is THE dust spot in Iceland – and the reason why we are will spend two month somewhere in nowhere.
During the afternoon, individual dust plumes merge into a decent haze layer drifting with the wind. In particular in the middle Flæður region we observe lots of individual events … until the water floods the river bed and shuts of the dust source until the next day. 

Paradise is still not so super dusty. However, we do have individual dust plumes and devils paying our instruments a visit. Still a bit shy, though. We are sure, once the surface here is dried up like the river bed further upstream is already, it will start blowing substantial amounts of dust. It simply has to!

Some of our OPC stations are now additionally equipped with two different types of passive dust samplers: Sedimentation plates, a sticky filter disk aligned horizontally in the air flow collecting dust particles suspended in the air overflowing the disk, and passive dust samples, that collects dust from the air flow in a bottle.