A while ago I was asked by the university (#realfaguib) if I wanted to present myself and my work in a short movie that they want to show to future students – and a few days later I found my office occupied by cameras of different sizes and three very nice journalists/moviemakers/photographers that came along. I quickly realized that making a short movie – I think they only want a minute or two – takes a loong time! Repeat, repeat, repeat – look into the camera, walk faster, walk slower, one more time, slower, shorter, clearer, louder, start over, look that way, look here, smile, don’t smile… at the end of the day, I was quite happy that I’m not a Hollywood movie star but an oceanographer in Bergen
Camera – and light – invasion of my office!Kjersti and me doing our best to ignore the camera…
I remember vivid discussions with Anna over a loaf of freshly baked bread from our new bread machine. We were in the Southern ocean, somewhere in between New Zealand and the Getz Ice shelf in the Amundsen Sea on board the Korean icebreaker Araon and we talked about the moorings we were about to deploy, the proposal we have started writing, the experiments we wanted to run – but most of all we talked about what actually happens when ocean currents meet an ice shelf front. That was four years ago – and I’m super excited to see that a few days the results of those discussions (and a good deal of work on board Araon, on and around the rotating Coriolis platform in Grenoble and in numerous offices around the world) were published in Nature! Ice front blocking of ocean hear transport to an Antarctic ice shelf by A. Wåhlin, N. Steiger, E. Darelius, K. M. Assmann, M. S. Glessmer, H. K. Ha, L. Herraiz-Borreguero, C. Heuze, A. Jenkins, T.W. Kim, A. K. Mazur, J. Sommeria and S. Viboud – in Nature! (For those of you who are not into peer reviewed litterature and scientific publishing – this is probably scientific equivalent to an Olympic gold medal!)
So what did we find out – well, to make a long story short – we oceanographers talk about two types of currents. They are both driven by pressure gradients – but for what we call barotropic currents, the pressure gradient is caused by differences in sea level (i.e. in how much water there is) while for baroclinic currents, the pressure gradient is caused by differences in density (i.e. how heavy the water is). The barotropic current is depth independent – this means that the current is equally strong from the surface down to the bottom, while the baroclinic current changes in strength (and potentially in direction) with depth. Our observations showed that the currents bringing heat towards the Getz ice shelf had both a barotropic and a baroclininc (bottom intensified) part. The barotropic part was the stronger one and the one carrying the majority of the heat. But when the current reached the ice shelf front (Anna was brave enough to deploy a mooring only 700m from the ice shelf front) – the strong barotropic current had to turn, and only the weaker baroclinic current was able to enter the ice shelf cavity. The experiments at the rotating table showed the same thing – barotropic currents turned at the front, while baroclinic currents could enter.
Experiments at the Coriolis platform in Grenoble – a 13 – m large combination of a swimming pool and a merry-go-round!
You can read more about what we did in the Coriolis lab here, and about when Karen recovered the moorings here
Today I’ve been listening in on the COSMUS cruise-planning meeting at AWI in Bremerhafen – it’s been great to hear all the groups that are joining the cruise tell about the exciting research that they are planning! During 75 days – no that’s not a typo, 75 days or almost eleven weeks* – at sea, physical oceanographers, sea-ice physicists, all sorts of biologists and bio-geo-chemists will live and work onboard Polarstern – and people will do so many cool things! There will be bottom landers that measures the oxygen consumption of benthic fauna, bottom crawlers that map the ocean floor at millimeter precision, microplastic filtering, profiling with high cameras to quantify the amount of sinking organic matter… and off course plenty of good old CTDs and moorings! There will also be seal tagging, and I was excited to see my name in the group of people that gets to go on the ice and actually meet the beasts up close!
I joined Polarstern on a cruise in 2005, when I’d just started on my PhD. I bet many things will have changed – but rumours has it that “Zillertal” (the small bar) is still around!
Joining Polarstern in Cape Town for my first Antarctic cruise in 2004. In 2021 I’ll do it once again.
*I didn’t tell my husband yet that the cruise will be that long, not quite sure about how to break the news… I’ve been told to tell things like that when there are lots of people around – and preferably nice food on the table… but I’m not sure about that one!
Congratulations to @MarkusMelin4 and @cisprague who has recovered four out of four moorings in the Amundsen Sea! Despite fishing vessel rescue-operations, iceberg-on-top-of-mooring-problems and strong winds the four moorings and all of the instrumentation are now safely on deck! One of the top boys had suffered from an iceberg encounter and the connector plug on my ADCP (A large instrument that measures the current velocity in the water column using acoustics and Doppler theory) had been leaking…. but that’s just little scratches when you consider that they’ve spent two years in the water!
I look forward to see what the records has to tell us about the currents and the hydrography around the Getz ice shelf. Stay tuned!
Uff – seawater can do horrible things to instruments. Luckily it can be repaired! Photo: Markus Melin
CTD – which is short for Conductivity-Temperature-Depth – is indeed a much appreciated instrument by every (sea-going) oceanographer. You send it down to the bottom of the ocean, and back comes nice profiles of temperature, conductivity (from which one can calculate salinty) – and whatever other sensor you’ve attached (oxygen, chlorophyll, and turbidity for example)
The CTD in its rosette on its way down into cold Antarctic water on a Polarstern cruise.
Most of the time the CTD is mounted on a rosette, which carries bottles so that one can also collect water samples from selected depths. But make sure to have the bottles open when you send them down – otherwise they will implode, and that is not a good thing, believe me!
Filling bottles with water at the freezingpoint (-1.9C) is a cold job!
The first mooring was successfully recovered yesterday (hipp hurray!) by @cisprague & co onboard Araon – but then Araon had to steam towards the Ross Sea to help a fishing boat that sent out SOS – alarm. Finger’s crossed for a happy ending – and a quick return to science.
Araon is steaming south for a new expedition to the Amundsen Sea and it’s now out of range on marinetraffic.com (unless you pay) … but @cisprague (Christopher Iliffe Sprague – one of two Swedish students on board who will hopefully recover the moorings Karen & co deployed two years ago) is still on Twitter so internet connections onboard must have improved since I was onboard in 2016… the icebergs look the same, though!
Have a happy cruise – and good luck with recoveries & science!
Not much polar oceanography in this post… but a lot of colors, physics (or is it chemistry?) and most importantly, a lot of fun! so I thought I’d share the results of me and my daughters playing in the kitchen a few evenings ago. (not much homework this week!)
Guess what will happen? (you’ll find the answer at the bottom of the post)
Milk, food coloring and a bit of soap was supposed to create a firework of colors… didn’t work out (the dye just sank when we added the soap) but it got pretty anyway!
DIY-lava lamp! Sunflower oil, food coloring, water and some aspirin make the trick!
Impressive equilibrium… much easier than it seems! We even managed to put the match on fire!
Toothpaste for elephants? Didn’t know where to get hold on H202 stronger than 3% (which I found at the pharmacy) so our toothpaste was nothing like the crazy ones we saw on youtube… but definitely the children’s favorite!
Then come and join us! We are currently have one PhD position at the University of Bergen (apply here*, deadline 10/1, 4 years) and one position at the Norwegian Polar Institute in Tromsø (apply here, deadline 7/1, 3 years) open. Both candidates will work on processes related to oceanic heat transport and melting ice shelves in the Weddell Sea, Antarctica – an exciting topic! If you’ve got questions about the positions, then don’t hesitate to contact me!
*The position in Bergen is announced only in Norwegian since it includes 25% duty work related to the project “EkteData” which aims to increase the interest for math and science among high school students. The candidate must therefor speak a Scandinavian language.
… and happen to be in Bergen 12 or 13 December, 2019? Then you shouldn’t miss out on the concert in Grieg Hallen where the Bergen philharmonic orchestra and researchers from University of Bergen joins up on the stage to take us on a cultural&scientific journey to the the depths of the oceans! You can read more about the concert series here (in Norwegian only).
On Friday I’ll be in the entrance during the pause together with a couple of “Nansen water catchers” and Snotra, one of UiB’s amazing gliders – see you there!
Seaglider deployment in the Iceland Sea. Photo: K. Våge
