East Greenland Current Instabilities

The coast off north-east Greenland is a grey, cloudy, and icy place. I spent 4 weeks on a ship earlier this summer to place sensors on the ocean floor to measure water currents, salinity, and temperature. The data shall uncover the mystery of how ocean heat 300 m below the surface gets to glaciers to melt them from below year round. My contribution is a small part of a larger effort by German, Norwegian, Danish, American, and British scientists to reveal how oceans change glaciers and how oceans impact Greenland’s ice sheet, climate, and weather.

So, for months now I am watching rather closely how this ocean looks from space. Usually it is cloudy with little exciting to see, but for 4 days this week the clouds broke and displayed a violently turbulent ocean worthy of a Van Gogh painting:

Satellite image ocean current instabilities on Aug.-19, 2014 as traced by ice along the shelf break, red lines show 500, 750, and 1000 meter water depth. Small blue triangles top left are ocean moorings.

Satellite image of ocean current instabilities on Aug.-19, 2014 as traced by ice along the the shelf break, red lines show 500, 750, and 1000 meter water depth. Small blue triangles top left are ocean moorings.

A wavy band of white near the red lines indicates the East Greenland Current. The red lines show where the water is 500, 750, and 1000 m deep. All waters to the left (west) of the red lines are shallow continental shelf while all waters to the right (east) are deep basin. Some islands and headlands of Greenland appear on the left of the image as solid grey. The image covers a distance about the same as from Boston to Washington, DC or London to Aberdeen, Scotland. Black areas are ocean that is clear of ice while the many shades of white and gray are millions of ice floes that act as particles moved about by the surface flow. Using a different satellite with much higher resolution shows these particles. The detail is from a tiny area to the north-west of the red circle near 77.5 North latitude:

Individual ice particles as seen on the north-east Greenland shelf from LandSat 15-m resolution from Aug.-21, 2014 near 77.5N and 10 W.

Individual ice particles as seen on the north-east Greenland shelf from LandSat 15-m resolution from Aug.-21, 2014 near 77.5N and 10 W.

Strongly white areas indicate convergent ocean surface currents that concentrate the loose ice while divergent ocean currents spread the ice particles out in filaments and swirls and eddies.

This is how many real fluids look like if one takes a snapshot as satellites do. Stringing such snapshots together, I show the fluid motion as comes to life for about 3 days:


Notice how the large crests seaward of the red line between 74 and 75 North latitude grow and appear to break backward. This is an instability of the underlying East Greenland Current. It starts out as a small horizontal “wave,” but unlike the waves we watch at the beach, the amplitude of this “wave” is horizontal (east-west) and not vertical (up-down). The mathematics are identical, however, and this is the reason that I call this a wave. As the wave grows, it become steeper, and as it becomes too steep, it breaks and as it breaks, it forms eddies. These eddies then persist in the ocean for many weeks or months as rotating, swirling features that carry the Arctic waters of the East Greenland Current far afield towards the east. The East Greenland Current, however, continues southward towards the southern tip of Greenland. The wave and eddy processes observed here, however, weaken the current as some of its energy is carried away with the eddies.

I could not find any imagery like this in the scientific literature for this region, but similar features have been observed in similar ocean current systems that transport icy cold waters along a shelf break. The Labrador Current off eastern Canada shows similar instabilities as does the East Kamchatka Current off Russia in its Pacific Far East. And that’s the beauty of physics … they organize nature for us in ways that are both simple and elegant, yet all this beauty and elegance gives us complex patterns that are impossible to predict in detail.

Beszczynska-Möller, A., Woodgate, R., Lee, C., Melling, H., & Karcher, M. (2011). A Synthesis of Exchanges Through the Main Oceanic Gateways to the Arctic Ocean Oceanography, 24 (3), 82-99 DOI: 10.5670/oceanog.2011.59

LeBlond, P. (1982). Satellite observations of labrador current undulations Atmosphere-Ocean, 20 (2), 129-142 DOI: 10.1080/07055900.1982.9649135

Solomon, H., & Ahlnäs, K. (1978). Eddies in the Kamchatka Current Deep Sea Research, 25 (4), 403-410 DOI: 10.1016/0146-6291(78)90566-0

American Adventures Abroad: The Four Germanies

I am American and damn proud of it. I was born in Germany, left almost 30 years ago, and, like a plant from another ecosystem, I am exposed to the new Germany for the first time. I know the difficult histories of both West and East Germany that since 1989 are one united country. The 100 people aboard the research icebreaker R/V Polarstern perhaps represent this new country well. Most crew and scientists were born and raised in either East or West Germany, extinct countries which each had a range of characters to form a distinct and diverse German fabric:

The first person I met when boarding the ship in dry dock was X. After introducing myself as an American scientist to sail the FS Polarstern in stilted if decent German, he revealed to me that he volunteered in the NVA, the soviet-style Nationale Volks-Armee for more than 10 years. Like many low-level Nazis a generation or two before him, he argues that not all was bad in the regime that he served. While this may be true, it strikes me odd, that this is the first things one reveals of oneself and a regime that created walls and killing zones to prevent its own citizens from leaving. Suspecting an uneasy history of guilt, I did not argue despite strong feelings to present different perspectives. Hence his next move is to state that American activities in Europe, Asia, South-America, Middle East, and Africa are the root source of all the problems in these regions. Again, not taking the bait, I listen, ask gentle probing questions to expose more detail, however, not much follows after the first rant that, perhaps, reflects a general feeling more than fact. I heart variations of this theme often in Germany both at sea and on land.

Our nurse and stewardess Kerstin also hails from the former East-Germany where she grew up the same time that I did in West-Germany, but unlike X., she embraces life as it presents itself without resentment, regret, or judgment. She signed on for a year working aboard Polarstern for a sense of adventure and to see the world in a different way. She is naturally curious on all things that relate to people, science, and life. She has little interest in politics, ideologies, and theories on how the world works, but she uses her own mind, experiences, and stories to make everyone around her laugh often. People like her should run the world.

The second Mate, Felix, was in charge when I boarded the ship. He is probably in his early 30ies and gave me the first tour of the ship in dry dock, a task that revealed a deep pride in the ship, its capabilities, and all it represents in a forward-looking modern Germany. He has clearly sailed to many ports and dealt successfully with people of different countries, cultures, and educations. Despite cursing and cussing of an ol’ salt, he is a hard-working, no-nonsense guy who gets things done efficiently. He also smokes like a chimney and likes to drive the ship while breaking sea ice. He did this often and smartly throughout the expedition.

A wonderful surprise to me aboard this ship is the large number of foreigners. There are three Danes aboard one of whom hails from New Zealand; two Canadians, two Belgians, and two Englishmen are aboard; while Brazil, China, Netherlands, Poland and the USA are each represented by one scientist. The two Canadians may as well come from two different countries, as one hails from English-speaking British Columbia and the other from French-speaking Montreal. Catherine’s Quebecoise language and perspectives are the most beautiful of all on this diverse ship. I could listen to her for hours …

Then there is a fourth group aboard who are perhaps the largest: They are the very young Germans who were born after the collapse of the communist empires in the East and they will become the new Germany. It is a foreign country to me, one I like from the distance, and it is a very young country with much potential to make a positive impact in the world.

Science party aboard R/V Polarstern after 4 weeks at sea in July 2014.

Science party aboard R/V Polarstern after 4 weeks at sea in July 2014.

Arctic Oceanographers Ashore In Tromso

Oceanographers are a bit crazy. This is especially true after sailing and working 4 weeks aboard a ship in the ice and fog and snow and drizzle that characterize summer in Fram Strait between northern Greenland and Spitsbergen. The one color one does NOT see is green, there just is none. So, when we got off FS Polarstern last thursday, what did we do? Continue reading

Men and Women on Edge 2

Bruce Chatwin came up during a late-night party aboard FS Polarstern this morning after all work and packing was completed this last day of a 4 week expedition to Fram Strait, a deep connection Continue reading

Men and Women on the Edge 1

EDIT: Original post was too long and rambling. One advice by wise female council, I decided to turn this into two separate posts. This is the first. July 5, 2014.

The “Quiet American” is not a popular book in the United States of America, but to me it described the dilemma and dangers of being American very well. Continue reading