PS114 - Weekly Report No. 1 | 10 - 15 July 2018

Into the Arctic

[16. July 2018] A walk through the ship shows: Everything is ready to go! Just a few days ago there were partly unpacked transport boxes everywhere (from whole containers to small cardboard boxes).

On Tuesday morning we, that means 47 scientists, boarded Polarstern in Bremerhaven. After a long dock time in the shipyard there are always many last-minute jobs to do. Nonetheless we cast off punctually at 10 am. We had a couple of additional persons on board in the locks and then on the river Weser who set up some of the new instruments installed in the shipyard. After they went from board we set out on our long transit northward to our study area. By now we are almost in the Fram Strait, between Svalbard and Greenland, at the transition between the Nordic Seas and the Arctic Ocean.

Fig. 1: An acoustic release, which is mounted at the bottom of a mooring line, is being tested. The release allows us to unfasten the mooring from the sea floor after 1 to 2 years in the water and to retrieve it at the sea surface. (Photo: Alfred-Wegener-Institut)

Fig. 2: An instrument, which will be mounted on a mooring line and which takes water samples every 8 days, is being filled with necessary liquids and the mechanical components are adjusted. (Photo: Alfred-Wegener-Institut)

During the first three days we had brilliant weather, calm seas and it still got dark at night. Yesterday the fog crept up and the temperatures dropped below 10°C. The general comment was, that now it feels just like every other year in our study area. And at night it no longer gets dark.

The long transit allows us to prepare without having to rush. This extra time was especially helpful because we have a total of seven 20-foot containers with gear that needed to be sorted. The space on board had to be allotted to the different groups, since the gear had to go somewhere. And, of course, everyone wanted to have a comfortable and convenient work space. In the end a solution for that was found.

This cruise will cover a lot of mooring work. Moorings are cables that are deployed vertically in the water column for 1 to 2 years and on which different instruments can be mounted. These instruments can continuously measure the water properties, such as temperature, velocity or nitrate concentration and light over several years. Additionally, they contain instruments which take water samples and samples of particles in the water column which can then be analysed in the lab. Since 2016, the FRAM Infrastructure Initiative has resulted in the addition of many different and sometimes novel instruments deployed in our moorings. This means that almost a third of our scientific party is kept busy with the preparations for more than 10 different instrument types (Pictures 1 and 2).

Fig. 3: Large Volume air samples are taken on the sighting platform on top of the bridge. They will be used to determine the concentration of organic trace compounds. (Photo: Alfred-Wegener-Institut)

Fig. 4: We managed to fit three gas chromatographs on this table. They will measure climate active gases from water samples. (Photo: Alfred-Wegener-Institut)

Still, countless types of data cannot (yet) be measured by our moorings. Because of that, many of our cruise participants collect samples which will be analysed on board. Some of these air and water samples are already being taken during our transit. These are used for example to determine the distribution of long lived organic compounds as well as the species distribution of small phytoplankton. Nitrate isotopes are used to follow the path of energy through the food web. A lot of instruments have been set up for these measurements (Picture 3).

We will also take video images and samples of the water column and the sea floor in our study area. Numerous filtration devices are set up to pump particles from the water which are then used for further analysis in the lab. Additionally, we will measure numerous gases on board the ship (Picture 4).

Our team consists of a lot of old hands, but also quite a few newcomers. Because of this we had a lot of explanations and briefings next to the general preparations and anticipation for the work to come. After all, we want to explore new things which call for complex instruments and work flows! By now we are well prepared and look forward to our first mooring retrieval on Monday.

With the best regards,

Chief Scientist Wilken-Jon von Appen on behalf of the scientific crew on board Polarstern