Our latest paper from the Amundsen Sea was highlighted by eos.org! You can read what they Write about Our work here!
Highlighted!
Finally stepping on sea ice
Do you think it is possible to stand on an 18 cm thick sea ice floe without breaking through?
Just one week ago we almost got stuck with the ship in about 4 m thick sea ice further south. We couldn’t move south and not back north neither. This was scary and we already imagined how it would be to spend the whole Antarctic winter in the sea ice. As soon as the captain managed to break the ship free, he headed straight north to get out of the sea ice covered area. Although it was good to get into a safer area, we were disappointed that we didn’t get to do all the science we wanted to do closer to the ice shelves. And the most disappointing was that we didn’t get the opportunity to leave the ship and go on sea ice!
But suddenly before leaving the sea ice area for good we stopped for a sea ice station, because there was a perfect homogeneous ice floe that the sea ice scientists were eager to study. So four of the scientists were brought to the ice floe on a small boat and took sea ice cores to measure the thickness, temperature, salinity, phytoplankton content and chemical constellation. In the meanwhile, the rest of us sat in the day room watching them through the windows. We were very jealous at them who could get on the ice! At some point there was an announcement through the speakers: Everyone was allowed to go on the ice floe! This made us so happy that we all ran to get into the floating suits and to enter the small boat. Finally – after four weeks on the ship, we could get off and step onto a piece of ice! We were very excited, jumped on the sea ice, made pyramids, and took a lot of crazy pictures until our hands were frozen! It was amazing and a lot of fun also to see the ship from distance.
Although the ice floe looked very fragile and dangerous to step on, it was stable enough to hold all our jumps. It was fun and only the penguins were missing, but we could live with that. It was a great pay-off after the disappointment of heading north earlier than expected.
Changing plans…
My phone rang twice yesterday – the first time it was Anna Wåhlin, who had just sat her feet on land again in Punta Arenas, Chile after two months in the Amundsen Sea With Ran.
The second time it was a local, Bergen number and I was very surprised to hear Nadine’s voice on the line! It still amazes me, that (when things work) you can talk to someone on a ship in Antarctica and it sounds as if they are in the room next door…
She had bad news, there were too much ice, the captain couldn’t go nearly as far south as we had hoped for to deploy Our moorings and we have to move them further north to deeper water. 1500m instead of 800m. Where should we add the extra line? Should we rearrange the instruments? We discussed a bit and agreed on a solution.
When I woke up this morning there were five missed calls from the same Bergen number – and there was soon a new call from Nadine.
– More bad news. The captain couldn’t make it even to 1500m, they were now about to deploy the NPI mooring at 2000 m. What should we do with ours? No point in going deeper, we don’t have more lines to add and many of the instruments can’t be deployed that deep. Deploy it on Maud Rise? Move instruments over to the NPI mooring and bring the rest home? Bring them all home? Not an easy decision!
DIY drifters!
While Nadine is wathing icebergs drift by in the Southern Ocean, I brought the students in GEOF232 back to Masfjorden, a fjord just North of Bergen. No icebergs to be seen there (luckily), and the only thing we saw drift by was Our own DIY drifters that we had deployed in the fjord!
A drifter is simply an Object that drifts With the Ocean currents and then on a regular basis reports its position back. Now, you can pay a lot and buy a fancy drifter… or you can build Your own (almost as fancy). That’s what Our handy technician Helge Bryhni did! All you need is some paint trays, a bucket, flotation, some rope and chain – and one of these devices that you are supposed to put on your (expensive) car so that you can find it again if it gets stolen. To be on the safe side, Helge opted for a radar reflector and a water proof container.
[vimeo 322769334 w=640 h=564]
Video by Algot Peterson, UiB
The students got to decide where and how to deploy our four drifters – spread out or together? in pairs with different depths*? near a river outlet? on rising tides or sinking tides? – and once they were in the water they could sit back and follow the drift on their mobile phone!
*by adjusting the length of the rope we could Place the bulky plastic part of the drifter on the Depth we wanted, and the drifter would then follow (and show us) the water motion at that Depth.
Nice surprise!
Dear Dr. Darelius,
The editors of Geophysical Research Letters have selected your paper “Warm Circumpolar Deep Water at the Western Getz Ice Shelf Front, Antarctica” (MS# 2018GL081354) to be featured as a Research Spotlight on https://Eos.org and on the journal’s website. Congratulations!
I’ll post the links when they are out!
International women day
Back to RV Kronprins Haakon, we celebrate the international women today! While Elin is active in Bergen at Women in Science 14.15 @ Realfagsbygget and Anna gets excellent data from AUV Ran under the Thwaites Ice Shelf, we collected all women for a group picture on the Helideck! About 40% of the scientists on board are women, plus 3 women from the crew!
Photo: Rudi Caeyers, UiT
Ran under Thwaites II!
The new Swedish AUV (autonomous underwater vehicle) heroine Ran has returned from her second mission beneath Thwaites ice shelf! Just in time for the international women’s day tomorrow!
An AUV is sent down in the water with a pre-programmed mission, e.g. “dive down to 500 m depth, swim 2 km to the east while measuring salinity and temperature and then come back here so that I can pick you up”, while a “ROV” (Remotedly operated vehicule) is connected to and steered from the mother ship via cables.
The name Ran is borrowed from Nordic mythology, where she is the goddess of the deep sea. According to the legend (and wikipedia), Ran catches seamen in big nets and then keeps them with her at the bottom of the sea. Luckily Ran escaped both the nets and the sea ice that was closing up around her pick up spot… and made it safely back to the mother ship were Anna Wåhlin and the rest of the AUV-team was waiting. I bet they were nervous!
On her second trip, Ran ventured three kilometers in under Thwaites, and brought back information on the sub-ice shelf hydrography and currents but also water samples that will be analyzed back in the laboratory.
Ran and I have one thing in common – neither she nor I would be where we are today without Anna’s support and stubborness. I’m so happy Your “baby” is successfull, Anna. You’ve worked so hard for this to happen! Congratulations!
You can read more about Ran and the expeditions (in Swedish) here!
WOMEN IN SCIENCE 8/3 14.15 @ Realfagsbygget
… if you don’t know what to do on Friday afternoon… then maybe drop by the library in “Realfagsbygget”, Bergen!
… and yes, that’s me jumping with the penguins!
First paper from our Amundsen moorings published!
Guest blog by Karen Assmann
Maybe you remember the blog posts I wrote a year ago about the cruise to the Amundsen Sea onboard the South Korean icebreaker Araon? (If not, see here!) Maybe you have even been wondering what we have been doing with all the data we recovered? About two weeks ago we had our first paper using these data published in a journal called Geophysical Research Letters: Warm Circumpolar Deep Water at the Western Getz Ice Shelf Front, Antarctica
Our two years of data show that there is a constant flow of warm water towards the western Getz Ice shelf and that this flow is pretty fast (20 cm/s). The distance from the shelf break, where the warm water comes from, to the ice shelf front is just 110 km so it takes only about a week to get from the deep ocean basin to the ice shelf front and the water does not have time to cool down much along its way. Temperatures in the inflow reach up to 1.59°C at the ice shelf front which makes this water the warmest that has been observed at any ice shelf front in the Amundsen Sea. The water reaching the Getz ice shelf cavity is hence warmer than the water reaching the fast melting Pine Island and Thwaites Ice Shelves further east!
To investigate what drives changes in the temperature and thickness of the warm bottom layer, we compared our ocean observations to wind data from the area and found that stronger easterly winds in the area make it harder for the warm water to reach the ice shelf front, because they depress the warm bottom layer over the shelf break. Climate projections indicate that these easterlies will weaken in future, making it easier for the warm water to get to the ice shelf base. We also find that gradients in the wind field over the shelf break control the thickness of the warm layer on longer time scales. This is a mechanism that previous studies have used to link changes in the wind field to changes in ice shelf flow velocities and melt rates, but these studies have lacked oceanic observations to support their hypothesis. Our observations close that gap and prove that the ocean does indeed react in the way that these studies imply
There is more science using these and the other mooring at the western Getz Ice Shelf moorings in the pipeline, so watch this space!
This is the Getz ice shelf in the Amundsen Sea! Our moorings were placed within the yellow Box, and the observed mean current is shown in (b). Panel (c) show the mean wind field.
Treasure hunting in Antarctica!
Yesterday the weather finally allowed the technicians from the Nowegian Polar Institute (NPI) to leave the research station Troll and fly out to go treasure hunting on the Fimbull ice shelf! Two years has gone by since they last visited the sites where NPI installed sub-ice shelf moorings more than ten years ago… and where we two years ago installed an “ApRES”. While the sub-ice shelf moorings measure the temperature and the currents in the water beneath the ice shelf, the APRES measures how fast the ice thins, and we can then calculate the basal melt rate. When combining the records we can hopefully learn a lot!
Like most Places in Antarctica, the snow that falls on the Fimbull iceshelf never melts away, so there was a few meters of snow to dig through in order to reach the instruments and to download the oh so precious data – a true treasure hunt!
Judging from the photos, the solar panel system that Helge Bryhni, a technician here at GFI, helped me design in order to power my APRES, appear to have survived two Antarctic winters… and we are now eagerly waiting for the report on how they’ve performed… and to have a look at the new data!
More stories from the successful treasure hunt at the Fimbul ice shelf will appear at @oceanseaicenpi soon!
