Tag Archives: ice

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

Ruins of Fort Conger in the High Arctic

Retreating from Fort Conger, the U.S. Army lost 68% of its men to death by starvation and drowning. They were delivered to the northern shores of Ellesmere Island within sight of northern Greenland by the SS Proteus on August 12, 1881 and were left with ample food and fuel to survive and explore comfortably for a years or so. Continue reading

The Turbulence of Van Gogh and the Labrador Shelf Current

Vincent Van Gogh painted his most turbulent images when insane. The Labrador Current resembles Van Gogh’s paintings when it becomes unstable. There is no reason that mental and geophysical instability relate to each other. And yet they do. Russian physicist Andrey Kolmogorov developed theories of turbulence 70 years ago that Mexican physicist applied to some of Van Gogh’s paintings such as “Starry Sky:”

Vincent Van Gogh's "Starry Sky" painted in June 1889.

Vincent Van Gogh’s “Starry Sky” painted in June 1889.

The whirls and curls evoke motion. The colors vibrate and oscillate like waves that come and go. There are rounded curves and borders in the tiny trees, the big mountains, and the blinking stars. Oceanographers call these rounded curves eddies when they close on themselves much as is done by a smooth wave that is breaking when it hits the beach in violent turmoil.

Waves come in many sizes at many periods. The wave on the beach has a period of 5 seconds maybe and measures 50 meters from crest to crest. Tides are waves, too, but their period is half a day with a distance of more than 1000 km from crest to crest. These are scales of time and space. There exist powerful mathematical statements to tell us that we can describe all motions as the sum of many waves at different scales. Our cell phone and computer communications depend on it, as do whales, dolphins, and submarines navigating under water, but I digress.

The Labrador Shelf Current off Canada moves ice, icebergs, and ice islands from the Arctic down the coast into the Atlantic Ocean. To the naked eye the ice is white while the ocean is blue. Our eyes in the sky on NASA satellites sense the amount of light and color that ice and ocean when hit by sun or moon light reflects back to space. An image from last friday gives a sense of the violence and motion when this icy south-eastward flowing current off Labrador is opposed by a short wind-burst in the opposite direction:

Ice in the Labrador Current as seen by MODIS-Terra on May 3, 2013.

Ice in the Labrador Current as seen by MODIS-Terra on May 3, 2013. Blue colors represent open water while white and yellow colors represent ice of varying concentrations.

Flying from London to Chicago on April 6, 2008, Daniel Schwen photographed the icy surface of the Labrador Current a little farther south:

Ice fields seen in Labrador Current April 6, 2008 from a plane. [Photo Credit: Daniel Schwen]

Ice fields seen in Labrador Current April 6, 2008 from a plane. [Photo Credit: Daniel Schwen]

Ice in the Labrador Current as seen by MODIS-Terra on April 6, 2008. Blue colors represent open water while white and yellow colors represent ice of varying concentrations.

Ice in the Labrador Current as seen by MODIS-Terra on April 6, 2008. Blue colors represent open water while white and yellow colors represent ice of varying concentrations.

The swirls and eddies trap small pieces of ice and arrange them into wavy bands, filaments, and trap them. The ice visualizes turbulent motions at the ocean surface. Also notice the wide range in scales as some circular vortices are quiet small and some rather large. If the fluid is turbulent in the mathematical sense, then the color contrast or the intensity of the colors and their change in space varies according to an equation valid for almost all motions at almost all scales. It is this scaling law of turbulent motions that three Mexican physicists tested with regard to Van Gogh’s paintings. They “pretended” that the painting represents the image of a flow that follows the physics of turbulent motions. And their work finds that Van Gogh indeed painted intuitively in ways that mimics nature’s turbulent motions when the physical laws were not yet known.

There are two take-home messages for me: First, fine art and physics often converge in unexpected ways. Second, I now want to know, if nature’s painting of the Labrador Shelf Current follows the same rules. There is a crucial wrinkle in motions impacted by the earth rotations: While the turbulence of Van Gogh or Kolmogorov cascades energy from large to smaller scales, that is, the larger eddies break up into several smaller eddies, for planetary-scale motions influenced by the Coriolis force due to earth’s rotation, the energy moves in the opposite direction, that is, the large eddies get larger as the feed on the smaller eddies. There is always more to discover, alas, but that’s the fun of physics, art, and oceanography.

Aragón, J., Naumis, G., Bai, M., Torres, M., & Maini, P. (2008). Turbulent Luminance in Impassioned van Gogh Paintings Journal of Mathematical Imaging and Vision, 30 (3), 275-283 DOI: 10.1007/s10851-007-0055-0

Ball, P. (2006). Van Gogh painted perfect turbulence news@nature DOI: 10.1038/news060703-17

Wu, Y., Tang, C., & Hannah, C. (2012). The circulation of eastern Canadian seas Progress in Oceanography, 106, 28-48 DOI: 10.1016/j.pocean.2012.06.005

Cockpit’s View of Greenland’s Glaciers, Ice-Sheets, and Sea-Ice

The glaciers and ice-sheets of Greenland retreat and melt in a warming world. Towering almost 3000 meters above sea level the ice-sheet is so thick and heavy that it depresses the bedrock underneath below current sea-level. Monitoring the ice-sheet, outlet glaciers, and sea ice of Greenland, NASA’s Operation IceBridge flies aircraft packed with radars, lasers, and optical sensors each spring and summer all over Greenland. There are exciting blogs written by the scientists aboard as they live and work out of Greenland. And today I discovered that they also provide video feeds as their plane conducts measurements. Here is an example from yesterday:

I am not entirely sure on the exact location off south-east Greenland, perhaps this is the area near Helheim Glacier, e.g.,

Greenland's bed-rock elevation from Bamber et al. (2003) digital elevation model based on remotely sensed surveys of the 1970ies and 1990ies gridded at 5 km resolution.

Greenland’s bed-rock elevation from Bamber et al. (2003) digital elevation model based on remotely sensed surveys of the 1970ies and 1990ies gridded at 5 km resolution.

but this will become clear as soon as the data are released to the public. This usually happens within a few months. The wide and open data distribution and access is one of the greatest things about this mission. If you want to see where the plane is now, this is the screenshot I took just now (site)

Locations of NASA's P3 air plane near Jacobshavn Isbrae on April-10, 2013.

Locations of NASA’s P3 air plane near Jacobshavn Isbrae on April-10, 2013.

The evolution of Jacobshavn Isbrae retreat from 1851 through present. [From NASA's Earth Observatory]

The evolution of Jacobshavn Isbrae retreat from 1851 through present. [From NASA's Earth Observatory]

Jacobshavn lost its buttressing ice-shelf during the last decade and now rapidly discharges ice from the Greenland ice-sheet directly into the ocean at a rapid rate. Most likely, the ice-shelf was melted by the ocean from below (Holland et al., 2008). This type of accelerated discharge raises global sea-level, because ice previously sitting on Greenland’s bedrock moves into the ocean where it eventually will melt. In response to the ice removed, the bed-rock rises as there is less mass above it to hold it down (Khan et al, 2010). All this has actually been measured by satellites (mass-loss) and ground-based GPS (bed-rock response). We live in a dynamic and rapidly changing world where our sensors and software show new patterns of physics that have never been seen before. There is so much more to discover …

Csatho, B., Schenk, T., Van Der Veen, C., & Krabill, W. (2008). Intermittent thinning of Jakobshavn Isbræ, West Greenland, since the Little Ice Age Journal of Glaciology, 54 (184), 131-144 DOI: 10.3189/002214308784409035

Holland, D., Thomas, R., de Young, B., Ribergaard, M., & Lyberth, B. (2008). Acceleration of Jakobshavn Isbræ triggered by warm subsurface ocean waters Nature Geoscience, 1 (10), 659-664 DOI: 10.1038/ngeo316

Khan, S., Wahr, J., Bevis, M., Velicogna, I., & Kendrick, E. (2010). Spread of ice mass loss into northwest Greenland observed by GRACE and GPS Geophysical Research Letters, 37 (6) DOI: 10.1029/2010GL042460

CCGS Henry Larsen: More on People, Places, and Services

The Canadian Coast Guard Ship is powered by such a diverse and talented group of women and men from Newfoundland, Labrador, and beyond, that one or even two posts here hardly do justice to describe how well they run their ship and its many facilities that many mid-sized cities do not have. Monday I wrote about the people who run the power plant and electric departments as well as the seamen who fight fires and run fishing fleet and port facilities. Today I want to show the airport and talk a little about the civil administration that oversees and manages all aboard the ship.

Landing deck of the CCGS Henry Larsen with aircraft preparing for take-off to survey the ice conditions ahead. Shown are Chief Officer Brian Legge (far right) who is in command of the airport and is talking to Pilot Don Dobbin (2nd from right), scientist Renske Gelderloos (3rd from right), Ice Services Specialist Erin Clarke (4th from right), and Helicopter Engineer Pierre Autran performs last checks inside the helicopter. [Photo Credit: Canadian Coast Guard Ship Henry Larsen]

The airport consists of hangar, landing pad, helicopter, traffic control, and fire fighting stations. Don Dobbin was our pilot and Pierre Autran his engineer who was pulled out of retirement for this trip. Incidentally, Pierre and I had sailed together on the same ship in 1993 more than 200 miles north of eastern Siberia. Then all flights were prohibited by Russian aviation authorities: Politics were different 20 years ago, one hopes. No such threat of being shot down existed this year between Greenland and Canada, but for severe ice conditions and poor internet connections, the airport was very busy almost every day for both ice surveys ahead and behind the ship. It also supported landing parties to set up and/or service 4 weather stations.

Helicopter pilot Don Dobbin with scientist Dave Riedel on Hans Island servicing a weather station in the center of Nares Strait. Ellesmere Island in the background. [Photo Credit: Allison Einolf, Minnesota]

The air traffic control takes place both on the flight deck where Chief Officer Brian Legge is in charge and from the bridge where the officer-of-the-deck is in overall command as either First Officer Chris Steward or Second Officer Rebecca Acton-Bond place the ship, alert the entire ship, and often oversee other science operations as well. All of these are demanding jobs, all these jobs need precision in the concise communication of orders and permissions granted or denied as well as execution of all operations, because helicopter operations are probably one of the most dangerous and critical operations possible on the ship.

Attention to detail, clear communication, and calm execution lower the risk of death and destruction that helicopters can and often do cause. The National Science Foundation sent me to a 4-day course in helicopter safety and what to do if accidents happen over water or on land. It was a sobering course. For this reason, perhaps, Captain Wayne Duffett is almost always on the deck during flight operations, but as all good chief executives, he lets his officers and navigators run the operations but is available for help on consultation should it be needed.

Second Officer and navigator Rebecca Acton-Bond on a sunday on the bridge of the CCGS Henry Larsen in August of 2012 in Nares Strait. [Photo Credit: Canadian Coast Guard, Kirk McNeil, Labrador]

Leading Seaman and helmsman Melvin Cobb on the bridge. [Photo Credit: Canadian Coast Guard Ship Henry Larsen]

The navigator always works with a helmsman or quartermaster who steers the ship following instructions of the officer of the deck, they are on the look-out for ice and bergs to find the best routes. “Best” here refers to the route that requires the least amount of ice breaking. So, if there is one thing that icebreakers like the Larsen are really good at, it is how to avoid ice, because it is a violent and high-energy activity. Fuel is not cheap and less ice is broken, the faster and more efficient the tasks at hand can be accomplished.

And as all people on the ship, everyone has more than one job and this includes the helmsmen and quartermasters like Melvin Cobb or firefighters like Derick Stone, Carl Rose, Paul Gillingham, and Rueben Hillier. They are often members of the deck crew that help landing parties to get ashore and stay save while ashore. This involves the zodiac as well as guns to protect from polar bears:

Seamen Paul Gillingham and Rueben Hillier in the zodiac steered by Chief Officer Brian Legge in Alexandra Fjord, Ellesmere Island on Aug.-13, 2012. A tide gauge was recovered and re-deployed near this site. [Photo Credit: Canadian Coast Ship Henry Larsen, Barbara O'Connell]

Zodiac launched for a landing part to dismantle a weather station at Cape Baird, Ellesmere Island. Chief Officer Brian Legge at the helm with Melvin Cobb and Derick Stone in the back and center left of the boat filled with scientists Humfrey Melling, David Riedel, Andreas Muenchow, and Renske Geldeloos. [Photo Credit: Canadian Coast Guard Ship Henry Larsen]

Landing party at Cape Baird, Ellesmere Island to dismantle a weather station. Scientists David Riedel (foreground) and Humfrey Melling (background) are protected by Melvin Cobb (with gun) from polar bears. View is towards the north-west across Lady Franklin Bay to the west of Nares Strait. [Photo Credit: Renske Gelderloos, Oxford University]

Taking down a weather station on Cape Baird, Ellesmere Island, view is to the south-west. People from right to left, the author, David Riedel (kneeling), Melvin Cobb, and Humfrey Melling (covered). [Photo Credit: Renske Gelderloos, Oxford University]

Polar bear on an ice floe in Kennedy Channel as seen from the bridge as the ship was approaching a station a day’s polar bear walk from Cape Baird. [Photo Credit: Canadian Coast Guard Ship Henry Larsen]

There is still more to describe such as the hospital, the restaurant and bar, as well as the superior fishing of sailors and fishermen from Newfoundland to find and hook valuable items such as sensors and computers that some scientists left unattended for 3 or 5 or 9 years at the bottom of the unspoiled seas that border Arctic Greenland and Canada. There will be more … as there are more great people who make great science possible.