Tethersonde campaign
13.10. - 02.11.2014
Longyearbyen / Hornsund / Ny-Alesund, Svalbard

Research topics during the campaign

Description and goals
A big source of uncertainty in climate modelling is the parametrization of processes shaping the atmospheric boundary layer (ABL) in the Arctic. This campaing was aiming for a better understanding of the processes shaping the ABL and trying to find a way to improve their parametrization. It is expected that these will undergo big changes during the ongoing climate change; especially surface properties will be heavily influenced. For further information read: "Vihma et al (2914), Advances in understanding and parameterization of small-scale physical processes in the marine Arctic climate system: a review"

Simultaneous measurements were taken from three locations on Svalbard: Ny-Ålesund, Longyearbyen and Hornsund. This selection will open up the opportunity to examine the spatial variability of the ABL properties. Also it will be possible to see a temporal evolution on a larger / synoptic scale features in the measured profiles and frontal passages / changes in airmasses.

The work was carried out in Collaboration with UNIS, the University of Tartu and the Alfred-Wegener-Institute.

Reports from Longyeabyen (by Daniel)
I met Siiri at the airport at 5:00 in the morning to catch the flight to Longyerbyen. On that day two airlines had a connection going up there and of course we were on different planes. After a early morning coffee we had to say goodbye again. After a couple of hours and stops in Oslo and Tromsø. I arrived in the early afternoon. We started straight away with the preparations to have to Tethersonde up and running on the next day. Fortunately I had a safety training a few weeks earlier and had not to do it again. Not that it is no fun, but it was just nice to have more to to prepare the campaign.

Preparing the Tethersonde during night time. Due to regulations most of the operation took place at night. Also the polar night was approaching and "daytime" became more and more dark.
After arriving at our office at UNIS we were told that a polar bear had visited Longyerbyen. We just missed it by about half an hour. It was scared off to a place near where we wanted to work. How nice...a polar bear next door. We had a meeting with the head of safety at UNIS and agreed, that we can work if we take some extra precautions. During the day we brought equipment out to the "Old Aurora Station" in Adventdalen, which would serve us as a base for operations for the next two weeks. Due to regulations we were only able to take profiles, if the local airport has officially closed. Also we had every time to call in and ask, if we can start to work and also to tell them when we stop. Longyearbyen is a remote place and there are quite often emergencies or people, that had to be flown to the mainland for medical treatment. So every time a meidcal plane was coming in or the helicopter had to go out to help people in need we had to stop our measurments. Luckily this night nobody needed assistance and we were able to take our first profiles. Around 1 a.m. in the morning we stopped.

The polar bear came back to town. So the Governor of Svalbard decided to tranquilize the animal and fly it somewhere far away. We were able to continue our soundings in the evening. Often it is better to let your eyes adjust to the dark and use only small lights; that will allow you to sport a polar bear easier. But due to the unique set-up it was safer to have the lights illuminate the surroundings and work on our instruments in the dark; only with small head torches. (Daniel)

16. - 20.10.2014
We were able to collect a couple of interesting situations like a cold front moving in. Also the word spread across the city, that there are some people with a big, orange balloon. So we got more frrequent visitors during the night; sometimes as late at 2 a.m. in the morning. But of course we were always happy to talk to people, because once the system is set up it needs only little work to keep it running. So you sit quite a big amount of time in the station an wait for the balloon to go up and down. Unfortunately it was not possible to sleep, because we had to keep an eye on the tetherline (if it gets too horizontal the balloon has to be taken in. Also increasing wind speeds could inhibit a continuation of the measurments. The balloon can only operate in wind speeds up to 10 m/s. Afterwards the risk gets too high to loose or damage the balloon. Also the visitors often stayed for some time and helped us with getting the balloon back to the storage...a simple container for shipping. It was always a good feeling to have an extra pair of eyes to look out for polar bears. A few time we even had a dog guarding us. That was very much appreciated.

On Saturdays and Sundays it was possible to work partly during daylight.
21. - 26.10.2014
Our collaboration with the airport was very good, but sometimes they had to tell us "bad news". One day around around 4 p.m. we called them and asked, if we can start with our operations. No problem, just wait for one hour so that the helicopter is back. An hour later we called again. They were very sorry, but we had to wait another couple of hours. The helicopter was now back, but with a sick person on board. It seemed more severe and thez had to call in an ambulance plane from the mainland. We decided to call it a night, because the conditions were anyway not favorable and waiting in the hot-dog-stand for another few hours and then may not measure anyway...maybe better so safe some energy. Always working in the nighttime and preparing stuff during the day took away a lot of energy.
During the last night with Siiri we were only able to take one profile. It was rather calm and only very light snowfall. But higher up it was aparrently a bit more. A while after we started to turn back the tetherline we realized, that it had a crust of snow and ice of about 5 mm on it. Also the sensor, once close enough to see, had a icy crusting. No reason to risk equipment; especially because it didn't seem like an interesting situation anyway.
By then it was already decided, that we were able to continue the next week. Some of the UNIS students were happy to help me out after Siiri had to leave.

27.10 - 2.11.2014
This week was haunted by unfavorable weather. The first night or too we had too high wind speeds. Then we had one night of measurments. It was a bit hectic, because I was the only one with experience with the system and had to instruct the others while working on the system. Also some of the head torches were on strike and we had to work with minumum light. But fortunately the students were very motivated and also on guest from the week before popped up. He knew the drill and he had a bright head torch. And again his dog. After that it was much easier.
The next few days we had a kind of sand storm...very local just outside Longyearbyen. We didn't want to get sand and dirt in the system and once again were not able to work. In the end we only managed two nights of measurements. The last day was realy on the edge, but since the balloon was needed two weeks later for a course at UNIS we decided not to risk anything and just call it a succesful campaign.