Category Archives: Oceanography

North Greenland Glacier Ice-Ocean Interactions 2014

I will travel to Spitsbergen in six weeks to board the German research icebreaker Polarstern. She will sail west across the Fram Strait towards northern Greenland where some of the last remaining glaciers exist that still discharge their ice via extensive floating ice-shelves. If all goes well, we will deploy instruments on the bottom of the ocean across a 30 km wide submarine canyon (Norske Ore Trough). The instruments profile ocean velocities from the bottom to the surface of the canyon that connects the deep (warm) ocean to the shallow continental shelf areas which then connect to two large outlet glaciers, Zachariae and 79N Glaciers. These are two of three glacier that terminate the North-East Greenland Ice Stream (NEGIS) which contains about 15 per cent of Greenland’s ice sheet:

Speed of Greenland's ice sheet movements. NE indicates the fast-moving (red) North-East Greenland Ice Stream with 3 branches connecting it to the ocean. [From Mauri Pelto's blog]

Speed of Greenland’s ice sheet movements. NE indicates the fast moving (red) North-East Greenland Ice Stream with 3 branches connecting it to the ocean. [From Mauri Pelto's blog]

The most southern is Storstrommen Glacier, a tidewater glacier with an almost vertical glacial front attached to the bedrock. The next one up north is Zachariae Glacier which lost its extensive ice-shelf during the last 3 years in a dramatic collapse reported on Mari Pelto’s blog. Presumably, there is little floating ice-shelf left that is attached to the lacier. And only 30 km to the north, we have 79N Glacier whose real name is the Danish Nioghalvfjerdsfjorden. It rivals Petermann Gletscher in ice discharge, areal coverage, thickness, and more with one exception: Nioghalvfjerdsfjorden’s ice-shelf appears remarkabe stable, nobody knows why exactly, but it may provide clues on how Greenland’s ice sheet interacts with and responds to forcing by the oceans. I show a recent Landsat image taken from Neven’s Arctic Sea Ice Forum; the floating glacier is on the left (east) of the image with a set of 5-7 out-cropping islands towards the right (west) providing some pinning support for the ~30 km wide front of the glacier:

Landsat image of Nioghalvfjerdsfjorden on Mar.-22, 2014.

Landsat image of Nioghalvfjerdsfjorden on Mar.-22, 2014.

Our 2014 study area is actually to the east, just outside the frame of the above image. The reason is lack of ship time, as this year’s deployment is just a small pilot study to better prepare and understand a larger German-led experiment that will take place both on the glacier and its adjacent ocean and land in 2016 and, I hope, beyond. Furthermore, we are scheduled to be there in June, a tad early for all the sea ice to clear out of the area (79N Glacier MODIS summer imagery) which also explains my intense interest in how the ice develops. And a first fairly clear MODIS image came about yesterday morning:

Ice-covered coastal waters off northeast Greenland April 14, 2014. Red contour indicates 100-m water depth. The "horseshoe" shaped red island is Belgica Bank with Norske Oer Trough to its south-west.

Ice-covered coastal waters off northeast Greenland April 14, 2014. Red contour indicates 100-m water depth. The “horseshoe-shaped red island is Belgica Bank with Norske Oer Trough to its south-west.

Belgica Bank is about as big as the Georges Bank in the Gulf of Maine. In past decades rafted multi-year ice and tabular icebergs often grounded over shallow Belgica Bank and thus provided an anchor to maintain stability for a year-round land-fast ice cover called the Norske Oer Ice Barrier. This year-round land-fast ice area, however, disintegrated in 2003 and has become an intermittent and not a regular feature for unknown reasons.

Before I can get onto the German icebreaker in Spitsbergen, my 3500 kg of equipment had to be repaired, rebuilt, re-powered, and shipped from British Columbia to Germany via rail, ocean freighter, and truck. It all arrived in 86 pieces only last friday, two weeks behind schedule, because of ice and confused shipping schedules in the Canadian Gulf of St. Lawrence. Lots of great people in Canada, the USA, and Germany made it happen. Wish us luck for the next step in this exciting scientific exploration to reveal one of many of Greenland’s glacier and ocean mysteries.

Hughes, N., Wilkinson, J., & Wadhams, P. (2011). Multi-satellite sensor analysis of fast-ice development in the Norske Øer Ice Barrier, northeast Greenland Annals of Glaciology, 52 (57), 151-160 DOI: 10.3189/172756411795931633

Wadhams, P., Wilkinson, J., & McPhail, S. (2006). A new view of the underside of Arctic sea ice Geophysical Research Letters, 33 (4) DOI: 10.1029/2005GL025131

Arctic Heart Beat and Disappearing Old Ice

Have a look at this beautiful movie that shows how the Arctic Ocean moves its oldest and thickest ice around from 1987 through 2013:

[Credits: Dr. Mark Tschudi, University of Colorado and NOAA's]

The Beaufort Gyre moves ice off western Canada and Alaska clockwise while the Fram Strait outflow between eastern Greenland and Spitsbergen exports much of the ice into the North Atlantic Ocean with the East Greenland Slope Current. The dividing line between the westward flux (into the Beaufort Gyre) and the eastward flux (into Fram Strait) stretch out to the north of the Canadian Archipelago and Greenland.

My only quibble is that, according to the movie, no old ice exits via Nares Strait or the Canadian Archipelago which is not true. During our field work in Nares Strait from 2003 through 2012 we always met rather heavy, thick, and old ice streaming south:

A graduate student in our oceanography program, Autumn Kidwell, is credited with directing me to this movie. Oh, and the Norwegian Ice Service in Tromso has a job opening for a smart remote sensing person ;-)

Formation of Nares Strait Ice Bridges in 2014

Darkness and cold covers North Greenland, Ellesmere Island as well as Nares Strait, the waterway that connects these two inhospitable places. And despite the darkness of the polar night, I can see that three beautiful arches made of ice connect Greenland to Canada. It is possible to walk across water, if the water is frozen. Stuck to land, ice arches or ice bridges shut down ice motion while the ocean under the ice keeps moving. Lets have a peek at how this looked from space yesterday:

Ice arches of Nares Strait on January 26, 2014 from MODIS thermal imagery.

Ice arches of Nares Strait on January 26, 2014 from MODIS thermal imagery. Surface temperatures in degrees Celsius are all below zero despite the missing “-” sign stripped by Adobe Illustrator.

The colors above show the temperature that satellite sensors “see” at the surface of the ice. Red is warm, blue is cold, and grey is land, but “warm” here is still below the freezing point of sea water near -2 degrees Celsius, so even the red or “hot” spots are covered by ice. The 300 deep ocean in Nares Strait generally flows from north to south without trouble under the ice, but just behind the fixed arching ice bridges, it sweeps the newly formed thin ice away to the south. The “warm” spots that form to the south of each ice arches have their own stories:

Farthest to the north a massive ice arch spans almost 200 km (150 miles) across. It faces the open Arctic Ocean to the north and it formed a few days before Christmas 4-5 weeks ago. It was still shedding large ice floes from its edge as it tried, and finally succeeded, I think, to find a stable location. Nevertheless, one of its larger pieces of ice moved into Nares Strait on January-3, 2014 where it became stuck on both Greenland and Ellesmere Islands:

The large floe from the edge of the first ice arch becames firmly lodged on both sides of the 30-km wide entrance to Nares Strait on January-4 (not shown), perhaps aided by strong winds from the north with wind speeds exceeding 40 knots (20 m/s). This second northern arch then aided the formation of the third ice arch in the south. All three arches became first visible on January-8:

Jan.-8, 2014

Jan.-8, 2014

A subsequent lull and short reversal of the winds brought warm southern air masses into Nares Strait while water and drainage pipes froze at my home in Delaware:

Weather record from Hans Island at the center of Nares Strait for January 2014. [Data from Scottish Marine Institute in Oban, Scotland.

Weather record from Hans Island at the center of Nares Strait for January 2014. [Data from Scottish Marine Institute in Oban, Scotland.

“Warm” here refers to -10 degrees Centigrade (+14 Fahrenheit). Air temperatures in Nares Strait today are -21 degrees Celsius (-5 Fahrenheit) while ocean temperatures under sea ice are near -1.8 degrees Celsius (+29 Fahrenheit). It is these “hot” waters that “shine” through the thinner ice as the satellite senses the amount of heat that the ice surface radiates into space. More details on this one finds elsewhere.

I enjoy these elegantly arching ice bridges across Nares Strait, because they challenge me each year anew to question how sea ice, oceans, air, and land all interact to produce them. Nobody really knows. It is a hard problem to model mathematically and many graduate theses will be written on the subject. A student in our own program, Sigourney Stelma, just presented first results and movies of computer simulations of ice bridges forming. Perhaps I can convince her to post some of them on these pages?

Kozo, T.L. (1991). The hybrid polynya at the northern end of Nares Strait Geophys. Res. Let., 18 (11), 2059-2062 DOI: 10.1029/91GL02574

Kwok, R., Pedersen, L.T., Gudmandsen, P. and Peng, S.S. (2010). Large sea ice outflow into the Nares Strait in 2007 Geophys. Res. Let., 37 (L03502) DOI: 10.1029/2009GL041872

Muenchow, A. and H. Melling. (2008). Ocean current observations from Nares Strait to the west of Greenland: Interannual to tidal variability and forcing J. Mar. Res., 66 (6), 801-833 DOI: 10.1357/002224008788064612

Fish, Fashion, and Climate: Simple Thoughts on Complex Systems

I love pickled herring, but the fashion of eating this delicacy varies with changing cultures and climates. In northern Europe it used to be a standard fare, perhaps still is, but in my native coastal North-Germany it was poor man’s food Continue reading

First Research Mission for Norway’s new Icebreaker

The Norwegian government just committed ~$4,000,000 to explore ecosystems in the Arctic Ocean. This new study includes ocean surveys Continue reading