The month on Polarstern coming to an end

The cruise on Polarstern basically spanned a section across the Fram Strait, with the last station being in Kongsfjorden. As we sailed eastwards, approaching the station, Claudia and I were on deck to do underway measurements with a towed CTD. The night before we had seen the mountains of Spitzbergen in the distance, and whales had followed us all night, but now, the sea had become misty. Suddenly Andreas pointed behind us, and we now saw that we had sailed into the Fjord without noticing, and that we were now surrounded by steep mountains.

When the last station was finished we sailed down along the coast to meet up with AWI’s smaller research vessel “Heinke” which was doing fisheries research around Svalbard. For logistical reasons, some samples were transferred to Polarstern, so the dinghy went in and sailed over to get them. At the same time they took some awesome pictures of the two research vessels side by side. Mind blowing that Germany chooses to post so much money and energy into Polar research.


Heinke and Polarstern in Isfjorden

As we had been really efficient during the cruise (mainly because we were lucky with the weather) we had time for us to go visit Longyearbyen on Svalbard while the crew handled official things. We all queued up for the life boats, which took us to land despite of rain and 7 Bf wind strength. Longyearbyen came off as rainy and cold, and most of us made our way to the small shopping centre for a coffee and a cinnamon bun. Later we walked around a bit, and then went to visit the small Polar museum, which showed the history of adventurers trying to reach the North Pole in more or less crazy ways. After a few hours we were all pretty much cold and wet, and it was time to go back to Polarstern. In the small harbor sturdy sailboats were moored, and I love the north, but I have to admit that I wondered if the trip to Svalbard really is worth doing in a sailboat. The wind had picked up even more, and a few people were beginning to feel sick on the way back to Polarstern. So As we pulled up alongside, most were happy to leave the life boat. Makes you wonder what it would be like if we had to enter them in a real emergency – I guess the water and the people are not likely to be calm in such an event. Good thing that they make emergency drills with us on the first day on every cruise.
When everyone was back onboard we started the trip back to Tromsø where Polarstern would get ready for the next cruise. On the way we packed up our instruments, cleaned the labs and wrote reports. But many of us also volunteered to help out doing a “plastic transect”.

I guess many people have become aware of the growing problem of plastic in the ocean, with the horrific picture of whales washing up on beaches with bellies full of garbage and the so-called “plastic islands” in the large oceanic gyres. Despite of this, the large amount of plastic observed in the Arctic Ocean has surprised my colleagues working with the subject. On our cruise, Mine was in charge of measuring micro plastic with pumps on the CTD, but also used a number of different methods to account for larger pieces. One of the easier methods is to put a person on the deck of Polarstern for an hour, asking them to note the plastic they see as we steam towards our destination. Only problem is that it’s quite cold, so you need a fair amount of people to get a full transect from Svalbard to Tromsø. And in the end I think they managed to sign up enough to cover every second hour of the trip.

As part of her work at AWI, Mine has created a website with a litter database. Here, everybody can volunteer to count plastic while at sea. All that is needed is to take a georeferenced picture – automatic on most mobile phones as long as they have a signal I guess.

We reached Tromsø early in the morning, and sailed in through the Lofoten Archipelago in beautiful sunshine. Again. The trip to the Fram Strait was a great experience, but we were also all looking forward to seeing our families again.


A day on Polarstern

I wake up from the buzzing of my phone. It’s dark in the room and my eyes refuse to open. Whatever, I will sleep a bit more.

When I’m woken again, I don’t feel any more awake than I did the first time. But I know I should get up. I have been sleeping for nine hours – that somehow should be enough. The door behind our room is repeatedly slammed open and then closed, accompanied by running feet and muffled talking. There’s probably whales outside.


I go out in our room and look out the window. Claudia is still asleep, but I know that she wants me to open up the curtains so we get a bit of light in. It’s the Arctic summer, and never really gets dark, but our curtains block out all light. After taking a shower in our tiny bathroom I go out to find some breakfast. It’s noon, and everybody else already had lunch at 11.30. It’s the main meal of the day on Polarstern, and usually consists of potatoes, some meat, sauce and a bit of vegetables. It’s great if you’re into traditional German food. But it’s usually not really my thing. So I go downstairs to the crew’s cantina and fix myself some breakfast. Usually coffee and bread with peanutbutter or pancakes.

Then it’s time to drop by the winch room where Laura and Wilken are working to check up on what’s happening and how their watch has been. On Polarstern cruises, there’s a tight schedule of the different instruments that go in the water to collect the samples. Sometimes everything works out as planned, but often changes occur, so before each watch we need to know what’s going on – and then continuously keep an eye on the plan.

We have divided the watches in two 12-hour shifts, and I share the night shift with Claudia – working from four in the afternoon to four in the morning. In the beginning it was hard to get used to, but as time passed we actually came to like the night shift. On a busy ship like Polarstern, with almost 100 people on board, it’s actually quiet nice to get the quiet night to yourself.

We don’t work the whole 12 hours, only when the CTD goes in – which it often does at night. So I go back to the room, where I spent a couple of hours working on the computer. At home, I usually work remotely on supercomputers through the internet, but on Polarstern this is of course not possible. Instead, I read up on papers that I need to read, and work on my own papers. Later I meet with some of the others for coffee.

In addition to the physical oceanography work we do on board, Claudia and I have agreed to keep an eye on a machine that continuously measures gases in the atmospheric. So I go to the floor beneath the bridge and note how the measurements are coming along. Then I get a small bottle and go down to the working deck, where we take a water sample everyday. Here, all the work is carried out when we are on station, and I chat a bit with the crew before going upstairs again.

Slowly, people are going to bed, and Claudia and I start preparing for the CTD. In the winch room Mine is already writing down a detailed plan for the in-situ pumps that will be attached to the line. Mine works with plastic pollution, and the pumps will measure micro plastics in the water column. We talk through the plan with the crew, and Claudia suits up to go on deck and drive the CTD out. I stay upstairs to turn on the CTD and guide the measurements. It’s all a matter of communication between me, Sebastian who is controlling the winch and the crew on deck – both Claudia, Mine’s people and the deckhand.

Once the CTD is in the water I turn it on, and ask Sebastian to start the decent. On the way down we do stops at the depths discussed with Mine to mount the pumps. In the end the CTD is at depth, 1600 metres, we take the water samples that are planned here and then pull it up so far that the pumps are located in the designated depths. And then we wait. The pumps need to be in for 1.5 hours, so we have time to get a coffee and talk, while we also keep an eye on the bottom depth and the CTD depth. The crew on the bridge always make an effort to keep the ship in the same place for the duration of the station, but there will always be some drift, so we need to make sure that the CTD does not suddenly hit the bottom. Despite of it being in the middle of the night, it’s still light outside, and the mood is good in the room – though Mine is tense, she is always worried that something will happen to the pumps. Towards the end of the pumping, the deck crew go back down to receive the pumps, and when everybody is ready I ask Sebastian to start raising the CTD. On the way up we help each other to keep an eye on the pump depth, so the CTD can be stopped in time for the pumps to come off. And we stop at the designated depths for water samples. As we approach the surface, Claudia starts calling the people who will work with the water samples. They are in bed sleeping, and since we never really know when the CTD will be at the surface, we have a list with people to call. On the computer screen we have plots of the measured salinity, temperature and chlorophyll, so many of the water sample people drop by the winch room to get to know what to expect in their sampling; the physical environment affects the biology, and the biologists may decide to do extra measurements in certain cases.

Once the CTD is back on deck it is secured, and our job is over for now. The next is Nicole who measures plankton in a net. It’s early morning, and it’s time for Claudia and I to go to bed.



Steaming northwards through the Norwegian Sea

The Norwegian Sea is calmer than the Baltic had been during our three week summer holiday, and we are now steaming steadily northwards. People are busy preparing their gear for the first station and finding their way on the Polarstern.

Polarstern usually spends our summer in the Arctic and our winter in the Antarctic, with relatively short stops in Bremerhaven in between. This year, two cruises have been carried out in the ice covered area north of Svalbard already, and two additional cruises are planned in the Arctic after our cruise has finished.

Before the ship leaves Bremerhaven in the spring, everybody who will carry out research during the season will pack their gear in boxes or containers and have it put onboard. On Polarstern, everything is stored in such a way that the gear needed at a specific cruise will be stored in an accessible part of the ship. So when a cruise starts, everybody has to locate their storage area. Unfortunately, there had been some miscommunication, and it turned out that our container had been put in storage for the next cruise leg – with the opening right against a wall, and on a deck were containers can only be moved when the eight containers located at the deck above are lifted out of the ship. Luckily, the main instrument we are using, the CTD, is already in place, and the container mainly contains spare parts.

Our group is responsible for measuring salinity and temperature in the water column, and additionally for taking water samples that will be used by other groups to determine nutrients, chlorophyll, species composition and other things that I am not fully aware of.

Our cruise is a so-called “Hausgarten” cruise. The Hausgarten is an area in the Fram Strait where the state of the ocean has been measured by the AWI for many years. As the Fram Strait is one of the main gateways to the Arctic Ocean, these longterm measurements help us understand how the inflow into the Arctic is changing.


Towards the Fram Strait

As the plane approached Tromsø, we could see the rugged coast line below, with the islands of Lofoten clearly standing out. We landed in bright sunshine, marveling at the beautiful landscape around us. The trip had started at three in the morning when the sound of my alarm clock woke me up, and at four, before the sun had risen, a bus with passengers still half asleep left the Alfred Wegener Institute and headed for Hamburg airport. In Oslo our group met up with those who had flown from Bremen, and soon we were on our way towards Tromsø where the research vessel Polarstern was waiting.

We spent the night in a hotel at the water front, and in the morning I had the opportunity to take a walk along the harbor and across the bridge that connects the island with the mainland. The sun was shining brightly and the scenery absolutely breathtaking.

A bus picked us all up and drove us the short way to the fuel dock where Polarstern was waiting. Inside, we found our rooms and I found out I would was in a room with Laura and Claudia. I never even new that Polarstern had rooms for more than two people, but ours was really nice, with a section for use during the day and a section with beds that was somewhat closed off, making it easier to sleep while others are awake in the main room. This is great because the ship continues working during the night, so those on the night shift will have an easier time sleeping during the day.


It turned out that we would have to stay at the fuel dock until early evening, so we took the opportunity to go back to Tromsø for a couple of hours. It was Sunday, so the only stores that were open were the souvenir shops and the cafes. Laura got a thermo cup with northern light on it, and Claudia got a present for her husband. We went to the Polar Museum, which looked pretty small, but had elaborate exhibitions of the Norwegian early explorers like Nansen and Amundsen, and it displayed the story of the hunters who would over winter on Svalbard to hunt for walrus, polar bear and seals. Crazy lives they had. They had a shop selling books about the Polar ocean, but I didnt find Nansens books about the Fram expedition, which were bought by my great grandmother and I now have at home – it turned out that they were part of the exhibition inside

In the evening Polarstern started moving slowly away from the dock, and soon we were steaming out between the beautiful and majestic Lofoten Islands in the midnight sun. Most people were on the deck above the bridge, but it was cold and windy, and soon there was only a few people left. We entered the Norwegian Sea around midnight and continued northwards towards Svalbard and the Fram Strait.

Polarstern in Bremerhaven

“But where were the polar bears?” We were all on our way back to the car after visiting AWI’s ice breaker, the Polarstern – and Mattis has learned enough about my work to know that Polarstern equals ice and snow, which apparently equals polar bears. But they were not there. We did, however, see a helicopter, labs, sleeping quarters and even a film with penguins – but no polar bears.

For the past couple of years my work has focused on modeling the the Arctic Ocean biogeochemistry, and this summer I will probably participate in a cruise between Svalbard and Greenland. This area is called the Fram Strait, and it’s one of the main gateways to the Arctic, where AWI has monitored the water for several years to help explain how and why the Arctic Ocean is changing.

So when the Polarstern opened its’ doors for the public this weekend, we waited in line for the kids to see where I will go this summer. We actually had to wait in line for 2.5 hours… But Esben and I took turns in the queue, while the kids went around with the other one to check out the many activities. We saw ROV’s filming and taking samples under water, talked to the scientific divers and decorated a Polarstern bag to bring home with us. And for lunch Runa chose a bratwurst of course, we are after all almost real Germans.

And finally, after going through a metal detector and becoming registered we were allowed inside the Polarstern accompanied by our new friends from the long wait. It was nice to show the kids where I worked the last time I went and where I will be this summer. And we talked about the many different nets and machines, had a look in a microscope, saw the helicopter and even the air balloon, which the kids know from a book at home. Esben noted that the bridge had even more instruments than Jensine does, which is rather impressive, and it was cool for them to see where many of the pictures from the Polarstern have been taken.

It’s been five years since I last went on a cruise on the Polarstern. Back then my work focused on modeling Southern Ocean biogeochemistry, and especially the trace metal iron, and I was lucky to go on a 10-week cruise from Cape Town in South Africa to Punta Arenas in South America. My group was responsible for measuring chlorophyll and particulate organic carbon on the way, while others measured nutrient concentrations, oxygen, salinity, temperature etc.  All in all, it gave an overview of the conditions in the ocean when we were there and helped understand how the physics controls the biology to some degree. Apart from the interesting science, it’s quiet a privilege to go to such a special place as the Southern Ocean, and I am sure the next cruise will be another great experience.

A workshop in Potsdam; the Lena Delta

Currently, my work focusses on the Arctic Ocean – that is, the whole Arctic Ocean, a fairly large area. I don’t really focus on the many rivers that supply fresh water to the Arctic Ocean. But in connection with a permafrost conference in Potsdam, a friend and colleague of mine, Vera, arranged a workshop focussing on the Lena River, Lena Delta and Laptev Sea. I thought it would be interesting to join.

In case people are not really familiar with the Lena River or the Laptev Sea, I have embedded a map below.

The Lena River is located in a permafrost region, where the ground is frozen year round. It is the largest of the rivers supplying water to the Arctic Ocean. As the planet is warming, the question is how this area will change, if the water discharge will increase and how the substances it brings with it will affect the Arctic Ocean.

Up until recently, the Russian shelves have been dominated by ice, but in recent years, the ice is breaking up earlier and is formed again later in the season. This means that light can penetrate into the water, which probably mean that more biological production can take place.

But this region is so remote that only a few Russian research vessels visit, and therefore not much is known about the “old normal” or how this is changing. And it is in regions like this that our models can be used to gain more knowledge about what might happen as the ice becomes more scarce.


The view from my hotel window towards the Telegraphenberg where AWI has offices in Potsdam.

Sea-ice in our model

To understand how the Arctic sea ice is changing and how it affects for example the underlying ocean currents, we work with a global sea ice ocean model (FESOM). For the last few years, a lot of effort has been put into improving the representation of the sea ice in the model. One focus has been on the large cracks – or leads, to use the correct name, that we know exist in reality. These are very difficult to capture in large scale models, but my colleague Qiang has now succeeded in modelling these leads and has put a video of the results on youtube. In this run, the horizontal resolution is 4.5 km in the Arctic Ocean. That’s quiet high.

Changes in Arctic sea ice

I knew that climate change was occurring when I started working at AWI, but I was not aware of how rapidly the temperature is changing in the Arctic or to what extent it has changed the area of the sea-ice.

The thing is, that while temperatures are increasing all over the planet, the increase happens faster in the Arctic than anywhere else; studies show that the mean Arctic temperature in 2010 was 4 degrees C warmer than the average for 1968 to 2010. And 2010 was not a particularly warm year.

The most obvious impact of the rising temperature is that the extent of the summer sea-ice becomes gradually smaller with time. The September sea-ice extend, has almost been reduced by 40% since 1979. The picture below shows had the ice extend has changed since 1950, based on measurements and models.

The decrease in sea-ice does not just change the habitat for the ever popular Polar Bears, the increased freshwater content also changes the  stratification of the water column, which can lead to changes in the ocean advection and mixing, in the nutrient supply, species composition etc. This can in turn further impact the climate in the Arctic but also globally. I guess I will get back to that in another post.

Arctic sea-ice

Mean extent of Arctic sea-ice as measured by satellites and predicted by models. (from NCAR:

Other, and more obvious impacts of the reduced ice cover is, that it opens up for shipping across the Arctic Ocean, shortening the path from Europe to the Asia significantly and introducing hazards such as oil leaks to the Arctic environment. Also, drilling for oil may begin as the ice recedes.

Sea-ice has been continuously measured from space by satellites since 1979. Below I have added a film from NASA showing the record minimum of 2012, comparing it to the average distribution from 1968 to 1995.

The summer sea-ice extend has reached the lowest values in 2007 and 2012. 2016 does, unfortunately, appear to become another year with high Arctic temperatures and low sea-ice extend.