Tag Archives: Newfoundland

The Turbulence of Van Gogh and the Labrador Shelf Current

Posted on May 8, 2013 by | 2 Comments

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

→ 2 Comments

Posted in Oceanography

Tagged , , , , , , , , ,

Petermann Glacier Ice Islands: Where are they now?

Posted on January 30, 2013 by | 4 Comments

Two large calving events in 2010 and 2012 reduced the floating part of Petermann Gletscher by 44 km (28 miles) in length, 6 Manhattans (380 km^2) in area, and 42 gigatons in mass. But what’s a gigaton? Writing in The Atlantic Magazine, Julio Friedman states that if we put all people living on earth onto a scale, then we will get half a gigaton. So, Petermann’s two ice island weigh more than eighty times as all humanity combined. As a reminder, this is what the break-ups looked like:

Petermann Gletscher in 2003, 2010, and 2012 from MODIS Terra in rotated co-ordinate system with repeat NASA aircraft overflight tracks flown in 2002, 2003, 2007, and 2010. Thick black line across the glacier near y = -20 km is the grounding line location from Rignot and Steffen (2008).

Petermann Gletscher in 2003, 2010, and 2012 from MODIS Terra in rotated co-ordinate system with repeat NASA aircraft overflight tracks flown in 2002, 2003, 2007, and 2010. Thick black line across the glacier near y = -20 km is the grounding line location from Rignot and Steffen (2008).

It turns out that the smaller 2012 ice island is just as heavy as the 2010 island, because it is much thicker, about 200 m, 600 feet, or half the height of the Empire State Building in Manhattan. These thick and thin islands have since left Petermann Fjord and Nares Strait for more southern climes. The thinnest piece reached Newfoundland in the summer of 2011 where it melted away. Most of the thicker, larger, and heavier ice islands from Petermann and Ryder Glaciers now litter almost the entire eastern seaboard of Canada as the two largest pieces have split, broken, and splintered into many smaller pieces. Each of these still represents an exceptionally large and dangereous piece of ice that can wipe any offshore oil platform off its foundation. Luc Desjardins of the Canadian Ice Service now tracks more than 40 segments, some still bigger than Manhattan, some as small as a football field. The distribution along the 1500 km (1000 miles) of coast is staggering:

RadarSat imagery of eastern Baffin Island (bottom, right), western Greenland (top, right), and Nares Strait with Petermann Fjord (top, left) with pieces of Petermann and Ryder Ice Islands identified. [Credit: Luc Lesjardins, Canadian Ice Service]

RadarSat imagery of eastern Baffin Island (bottom, right), western Greenland (top, right), and Nares Strait with Petermann Fjord (top, left) with pieces of Petermann and Ryder Ice Islands identified as green dots. [Credit: Luc Lesjardins, Canadian Ice Service]

What stands out is that most pieces are close to the coast of Canada. This is expected, because often the ocean moves in ways to balance pressure gradient and Coriolis forces as we live on an earth that rotates once every day around its axis. This force balance holds both in the ocean and the atmosphere. We are all familiar with winds around a low-pressure system such as Hurricane Sandy where the winds move air counter-clockwise around the eye (the center of low pressure). This eye of low pressure in our ocean story is permanently near the center of Baffin Bay. Ocean currents then move water counter-clockwise around this eye. This results in a flow to the south off Canada and a flow to the north off Greenland. On a smaller scale this balance holds also, such as Delaware Bay or Petermann Fjord, but I will not bore you with the details of graduate level physics of fluids in motions … as important as they may be.

So, almost all the ice islands we see in the above imagery will make their way further south towards the Grand Banks off Newfoundland. Some are grounded to the bottom of the shallow coastal ocean and may sit in place for a year, or a month, or until the next high tide will lift the ice off the bottom and move it back into deeper water. Some ice islands will keep moving rapidly, some will further break apart, but none will go away anytime soon. If you want to see some of Petermann’s Ice Islands for yourself, take the ferry from North Sidney, Nova Scotia to Port aux Basques, Newfoundland and Labrador and head for the Great Northern Peninsula. That’s what I hope to do one of the next summers.

ResearchBlogging.org
Johnson, H., Münchow, A., Falkner, K., & Melling, H. (2011). Ocean circulation and properties in Petermann Fjord, Greenland Journal of Geophysical Research, 116 (C1) DOI: 10.1029/2010JC006519

Münchow, A., & Garvine, R. (1993). Dynamical properties of a buoyancy-driven coastal current Journal of Geophysical Research, 98 (C11) DOI: 10.1029/93JC02112

Rignot, E., & Steffen, K. (2008). Channelized bottom melting and stability of floating ice shelves Geophysical Research Letters, 35 (2) DOI: 10.1029/2007GL031765

→ 4 Comments

Posted in Ice Island, Petermann Glacier

Tagged , , , , , , ,

Shots of Airborne Lasers at Petermann Gletscher, Greenland

Posted on November 25, 2012 by | Leave a comment

If shots of whiskey make you dizzy, shots of laser stun. NASA stunned me this week, when I discovered that they provide millions such shots of Greenland from which to construct detailed images of the landscape. The shots are free, no age-limit. This is better than the usual remote sensing or photography of “just” brightness. The laser gives us height, and not just the perception of it by shadows and fake angles of illumination, but hard and direct measurements of, well, height above sea level. Have a look at several million such shots of Petermann Gletscher taken in 2010 before the glacier broke to Manhattan-sized pieces:

Petermann Glacier surface elevation from laser shots on Mar.-24, 2010 at the site where the Manhattan-sized ice island formed Aug.-6, 2010. The background shows the same scene at the same time at 250-m resolution from MODIS (see below). Colors along the 350-m wide laser track line show height above sea level in meters.

Petermann Glacier on March 24, 2010 as seen from MODIS satellite at 250-m resolution with two flight tracks along which laser data are collected. The black box shows the site of the figure above. The color figure on the right shows the slope or gradients of the data shown on left. It emphasizes regions where brightness changes fast. Multivariate calculus is useful!

We see two tracks: the one on right (east) has the ice stick more than 20-m above sea level (yellow colors) while about a mile to left (west) the ice’s surface elevation is only 10-m above sea level (light blue). Since the ice is floating and densities of ice and water are known, we can invert this height into an ice thickness. Independent radar measurements from the same track prove that this “hydrostatic” force balance holds, the glacier is indeed floating, so, multiply surface elevation by 10 and you got a good estimate of ice thickness. The dark blue colors of thin ice show meandering rivers and streams, ponds and undulations, as well as a rift or hairline fracture from east to west. This rift is visible both in the right and left track, it is the line along which the glacier will break to form the 2010 ice island. All ice towards the top of this rift has long left the glacier and some of it has hit Newfoundland as seen from the International Space Station by astronaut Ron Garan:

Last remnant of Petermann Ice Island 2010-A as seen from the International Space Station on Aug.-29, 2011 when it was about 3.5 km wide and 3 km long [Photo credit: Ron Garan, NASA]

Both are images of Petermann ice. The photo measures the brightness that hits the lens, but the laser measures both brightness and ice thickness. The laser acts like flash photography: When it is dark, we use a flash to provide the light to make the object “bright.” Now imagine that your camera also measures the time between the flash leaving your camera and brightness from a reflecting object to return it. What you think happens at an instant actually takes time as light travels fast, but not infinitely fast. So you need a very exact clock to measure the distance from your camera to the object. Replace the flash of the camera with a laser, replace the lens of your camera with a light detector and a timer, place the device on a plane, and you got yourself an airborne topographic altimeter. So, what use is there for this besides making pretty and geeky pictures?

The laser documents some of the change in “climate change.” Greenland’s glaciers and ice-sheets are retreating and shrinking. Measuring the surface and bottom of the ice over Greenland with lasers and radars gives ice thickness. The survey lines above were flown in 2002, 2003, 2007, 2010, and 2011. These data are a direct and accurate measure on how much ice is lost or gained at Petermann Gletscher and what is causing it. My bet is on the oceans which in Nares Strait and Petermann Fjord have increased the last 10 years to melt the floating glacier from below.

There is more, but Mia Zapata of the Gits sings hard of “Another Shot of Whiskey.” What a voice …

ResearchBlogging.org

Johnson, H., Münchow, A., Falkner, K., & Melling, H. (2011). Ocean circulation and properties in Petermann Fjord, Greenland Journal of Geophysical Research, 116 (C1) DOI: 10.1029/2010JC006519

Krabill, W., Abdalati, W., Frederick, E., Manizade, S., Martin, C., Sonntag, J., Swift, R., Thomas, R., & Yungel, J. (2002). Aircraft laser altimetry measurement of elevation changes of the greenland ice sheet: technique and accuracy assessment Journal of Geodynamics, 34 (3-4), 357-376 DOI: 10.1016/S0264-3707(02)00040-6

Münchow, A., Falkner, K., Melling, H., Rabe, B., & Johnson, H. (2011). Ocean Warming of Nares Strait Bottom Waters off Northwest Greenland, 2003–2009 Oceanography, 24 (3), 114-123 DOI: 10.5670/oceanog.2011.62

Thomas, R., Frederick, E., Krabill, W., Manizade, S., & Martin, C. (2009). Recent changes on Greenland outlet glaciers Journal of Glaciology, 55 (189), 147-162 DOI: 10.3189/002214309788608958

→ Leave a comment

Posted in Ice Island, Petermann Glacier, Polar Exploration

Tagged , , , , ,

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

Posted on September 13, 2012 by | 2 Comments

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.

→ 2 Comments

Posted in Nares Strait 2012, Polar Exploration

Tagged , , , ,

Nares Strait 2012: Grounded in St. John’s, Cod, and Crossing of Lines

Posted on August 1, 2012 by | 1 Comment

Hurry-up and wait: The rushed 5 am arrival at St. John’s airport this morning turned into a six-hour wait and a canceled departure for Thule, Greenland. Crew, officers, and scientists are all grounded and spend an extra night waiting. There is lots of talk about screeching-in and uncertainty if membership in the “Order of the Blue Noses” or the “Order of the Gold Dragons” substitutes the more mundane “screeching-in.” Let me explain:

Canadian authorities aboard CCGS Henry Larsen.

The CCGS Henry Larsen originates from St. John’s and most of its officers and crew are local to the town, island, and icy waters offshore where cod once ruled supreme until mis-managed industrial-scale offshore trawling almost wiped the cod out and destroyed much of the local economy that was based on cod for centuries.

Time series of (a) catch of cod (in 106 tonnes) over the Newfoundland and Labrador shelf (b) the total abundance of Gadidae over the southern Newfoundland shelf (c) the catch of shrimp and (d) crab over the Newfoundland and Labrador shelf (e) the greenness index from the Continuous Plankton Recorder (CPR) over the southern Newfoundland Shelf (f) bottom temperature from inshore on the southern Newfoundland shelf and (g) the North Atlantic Oscillation (NAO) index. The heavy solid lines in panels (f) and (g) represent low-pass filtered smoothed curves of the plotted data. [From DeYoung et al, 2004: Detecting regime shifts in the ocean, Prog. Oceanogr., 60, 143-164.]

The CCGS Henry Larsen has two crew who rotate on and off the ship every 4-8 weeks. Over the years I have met many crew who hailed from families who had worked the cod on smaller, inshore boats. They are superb and experienced sailors who know how to handle and run ships and all attached to it in harsh and icy waters. But how does this relate to screech and cod? Let me digress a moment by comparing US and Canadian Coast Guards:

The U.S. Coast Guard’s ice breaker operates 24-hours/day under military rules without alcohol or overtime to be had. In contrast, the civilian Canadian Coast Guard operates less hours at full strength with some alcohol and some overtime served in moderation. The cultures aboard US and Canadian vessels differ: US ships are permanently in training with young crew on 6-month deployments moving to a new assignment each year, while Canadian ships are working with an older, more experienced, and steady crews. The Canadian crews do the same amount of work in 12-18 instead 24 hours with 1/3 the staff. Ironically, US ships have more “unclassified” electronic capabilities with many more advanced sensor systems. Both ships also have “classified” sensors and missions that I know nothing about, but I digress. Cod and screech are potentially aboard Canadian ships operating out of Newfoundland only.

CCGS Henry Larsen crew at work: Deployment of a tide gauge (subsurface pressure sensor) in Alexandra Fjord. This is one of the instruments we will recover from Nares Strait that was deployed in 2009.

Our small motley crew of eight scientists this year consists of 4 Canadians from British Columbia, 3 Americans from Delaware, and 1 Dutch from England. Yesterday night we all converged at a fine restaurant on Ducksworth Street in downtown St. John’s, Newfoundland. A dispute is still raging among us on what is valid proof of earlier”screeching-in?” I learnt the hard way, that “laminated certificates” are invalid, but what about “un-laminated certificates?” The former are easily obtained in the vibrant port city of St. John’s with its many bars and pubs. The “un-laminated certificates” may be valid, if signed and authenticated by an officer of the CCGS Henry Larsen aboard said ship, but enforcement has been selective.

There are also arguments, that a crossing of the Arctic Circle (certified by a Commanding Officer of a Canadian Coast Guard ship) or the crossing of the International Dateline north of the Arctic Circle (certified by a Commanding Officer the CCGS Henry Larsen) may supersede the more common “screeching-in” ceremonies and certificates. I am the main person making these arguments facing authorities with powers that exceed mine by far.

Our failure to leave for Thule, Greenland today may give some of us a chance to get potentially needed “screeching-in” certificates, but I very much doubt that these “laminated certificates” carry much weight. Time will tell. It will also tell if we get to Thule tomorrow. Hurry-up and wait.

→ 1 Comment

Posted in Nares Strait 2012, Oceanography

Tagged , ,

Nares Strait 2012: First Challenges and Petermann Ice Island Coming

Posted on July 31, 2012 by | 9 Comments

Petermann Glacier’s 2012 ice island is heading south, the Canadian Coast Guard Ship Henry Larsen is heading north, and my passport went through the washer. Ticket agents at Philadelphia airport refused to accept my worn passport to get into Canada. My journey appeared at a dead-end, but ticket agents, U.S. State Department employees in downtown Philadelphia, and a Jordanian cab driver got me to Canada with a new passport, a new ticket, and a new lesson learnt in 4 hours. I did not believe it possible, but it was. I arrived in Canada with an entire day to spare.

Over the years I learnt to plan and budget generously for Arctic research, and then improvise with what is available. I was taught to bring spares of all critical equipment to prepare for loss and failure. I learnt to allow for extra time as missed planes, weather, and who knows what always make tight schedules tighter, like passports going through washers. I learnt that patience, civility, co-operations, and seeing the world through other people’s eyes and responsibilities get me farther than fighting. After I got my PhD in 1992, I learnt that the very people who cause troubles by enforcing rules and regulations are often also the most likely to know the way out of trouble. The ticket agent who denied my passport was also critical to help me get a new one. Thank you, Beth.

Our science party of eight from Delaware and British Columbia and the ship’s crew of 30-40 from Newfoundland will meet on the tarmac of St. John’s tomorrow at 4:30am, fly to and refuel at Iqaluit, Nunavut, and arrive at the U.S. Air Force Base at Thule, Greenland. The crew who got the ship from St. John’s to Thule will return with the plane home. It usually takes two days sailing north by north-west to reach Nares Strait from Thule, but this year the ice will be a challenge far greater than getting a new passport in 4 hours.

Western North-Atlantic and Arctic regions with Greenland in the west (top right) and Canada (left). Blue colors show bottom depth (light blue are shelf areas less than 200-m deep) and grey and white colors show elevations. Nares Strait is the 30-40 km wide channel to the north of Smith Sound, Baffin Bay is the body of water to the south of Thule.


The ice island PII-2012 is moving rapidly towards the outer fjord at a rate that increased from 1 km/day last week to 2 km/day over the weekend. I expect it to be out of the fjord an in Nares Strait by the weekend when we were hoping to recover the moorings with data on ocean currents, ice thickness, and ocean temperature and salinities that we deployed in 2009. The ice island is threatening us from the north: Without a break-up, it is big enough to block the channel as another large ice island did for almost 6 months in 1962.

Petermann Glacier, Fjord, and Ice Island on July 31, 2012 at 08:05 UTC. Nares Strait is to the top left. Petermann Glacier, Greenland is on bottom right. PII-2012 is at the center.


At the southern entrance to Nares Strait, lots of multi-year ice is piling up near the constriction of Smith Sound. Winds and currents from the north usually flush this ice into Baffin Bay to the south, however, the same winds and currents will move the ice island out of Petermann Fjord and into Nares Strait. We will need patience, humility, and luck to get where we need to be to recover our instruments and data. A challenge that cannot be forced, we will likely wait and go with the flow rather than fight nature. We will have to play it smart. We are the only search and rescue ship for others. I am nervous, because this year looks far more difficult than did 2003, 2006, 2007, or 2009. In 2005 we were defeated by the winds, but that is a story for a different day.

→ 9 Comments

Posted in Ice Island, Nares Strait 2012, Petermann Glacier

Tagged , , , , , ,

The currents and winds of Nares Strait

Posted on July 27, 2012 by | 6 Comments

[Editor's Note: Undergraduate Allison Einolf of Macalester College in Minnesota summarizes her work at the University of Delaware that was supervised by Andreas Muenchow as part of an NSF-funded summer internship.]

I’m about to fly to Thule, Greenland for a research expedition into the Nares Strait. We had planed to survey Petermann Fjord, but our proposed cruise track is facing an obstacle twice the size of Manhattan.

We’re heading up north to pick up instruments that have recorded current velocities, salinity, temperature, and ice thickness in Nares Strait since 2009. I’ve been working all summer on data retrieved on a similar cruise three years ago, focusing on what effects the ice arches have on currents north of the ice arches.

Nares Strait MODIS satellite imagery of the study area and ice arch April 21, 2008. Red dots are instrument locations. Arrows show current velocities.

Nares Strait MODIS satellite imagery of the study area and ice arch April 22, 2009. Red dots are instrument locations. Arrows show current velocities. Note the lack of the southern ice arch, but the presence of one north of the study area.

Continue reading →

→ 6 Comments

Posted in Ice Arch, Ice Cover, Ice Island, Oceanography, Petermann Glacier

Tagged , , , , , ,

Petermann Ice Islands Stuck in Ice

Posted on June 13, 2012 by | Leave a comment

Several pieces of the Manhattan-sized ice island that broke off Petermann Glacier, Greenland in 2010 arrived, dispersed, and melted off Newfoundland last summer. They provided stunning displays visible to the naked eye from the coast. The Canadian Ice Service just distributed this set of radar images showing 4 pieces that are all grounded and/or stuck in ice. None are moving.

Overview of fragments of Ice Islands that broke off Petermann Glacier, Greenland in 2010 as of June-11, 2012 from RadarSat composites. [Credit: Luc Desjardins, Canadian Ice Service]

In the open ocean ice is moved by winds stressing the ice from above and by ocean currents stressing the ice from below. Typical sea ice varies in thickness from 1-5 meters (3-15 feet) which is much less than the 30-130 meters (90-400 feet) thick ice islands. Winds thus push thick ice islands much less than they do push the thinner sea ice. Thick ice islands are moved by ocean currents, not winds.

This is why oceanographers like myself love these bits of ice islands to bits: they tell us about the ocean below the surface that satellites do not see, but, sadly, all fragments are stuck either to the seafloor in shallow coastal waters or are cemented in place by immobile sea ice that is “land-fast:” Think of it as ice that is glued to land and to each other. This sheet of glued-together ice extends some distance offshore. The distance can be a few yards during a cold winter night in Maine or 100s of miles off Siberia. Offshore islands, rocky outcroppings, or grounded ice islands all anchor land-fast ice by adding local support and thus strength and stability to the immobile land-fast ice.

Too much talk, lets explain this with an image of the largest ice islands, called PII-B1. It is about 4 km wide and 9 km long. I dropped a black dot in its center as it is hard to see where to look in this image. I also show land in grey, open water in blue, and ice in shades of white and yellow:

Land-fast and mobile sea ice off Baffin Island with Petermann Ice Island PII-B1 grounded near the 150 meter isobath (black dot). Thick lines are 100, 200, and 300-m bottom depths. MODIS Terra data at 250-m resolution from June-6, 2012, 15:05 UTC.

There is clearly a 30-km wide band of ice attached to the land with a line of blue water separating it from ice that is mobile and has different signatures. A blue band of ocean has emerged, I speculate, as the result of winds from the south that moved the mobile ice to the north-east (to the right in the image). Neither the land-fast nor the grounded ice island PII-B1 embedded in it moved, so open water appears where there was mobile ice before. This is called a shore lead and I bet there are plenty of seals and whales feasting there now. Note also the arched entrance to Home Bay (bottom left) where loose ice is scattered towards the headland of Henry Kater Peninsula.

As summer is arriving fast in the Arctic, the land-fast ice will disappear, breaking up as the sun and air above and the ocean below weakens the ice by melting. This will expose the thicker ice islands and icebergs to wind-forced storms and waves more violently than it does now. And even those ice island grounded to the bottom of the ocean in shallow water will become free during a time of higher than normal sea level, perhaps during a spring tide, perhaps during strong winds from the north. Then these currently stuck-in-the-ice ice islands will continue their journey south towards Newfoundland and the Atlantic Ocean that they began in 2010 when they were born in northern Greenland.

EDIT: For context I append an earlier RadarSat image from October-18, 2010 when all segments were much closer in space.

Petermann Ice Islands in northern Baffin Bay of Coburg Island, Canada at 76 N latitude on Oct.-18, 2010, about 2 month after they separated from Petermann Glacier, Greenland at 81N latitude. [Credit: Luc Desjardins, Canadian Ice Service]

→ Leave a comment

Posted in Ice Island, Oceanography, Petermann Glacier

Tagged , , , ,

Ice Drift from Nares Strait to Newfoundland: The 1871 Polaris Expedition and Petermann Ice Islands

Posted on January 10, 2012 by | Leave a comment

“Nineteen ship-wrecked members of the Polaris expedition of 1871-72
drifted on ice floes a distance of over 2500 km from Nares Strait near
79°N latitude to Newfoundland. Surviving this six months long ordeal,
they inadvertently mapped for the first time a drift of icy waters
from the Arctic to the North Atlantic Ocean. That they survived to
tell the tale is tribute to two Inuit, Joe Ebierbing and Hans Hendrik,
whose hunting skills and diligence provided food for the entire party
(Hendrik, 1878). Almost a century later, 1962-64, ice island WH-5 was
carefully tracked via ships and aircraft from north of Ellesmere
Island (83°N) to the Atlantic via Nares Strait (Nutt, 1966). The
movements of ice and water so revealed are one link in the global
hydrological cycle whose significance to global climate has yet to be
understood …” [from Muenchow et al. (2007)]

'Captain Hall's Arctic Expedition -- The "Polaris"'', a wood engraving published in ''Harper's Weekly'', May 1873.

The BBC contacted me this morning asking great questions related to the Petermann Ice Islands and icebergs. These reminded me of the opening paragraph quoted from a paper on the oceanography of Nares Strait. I published it in 2007 with two friends and fellow sailors of icy waters, Kelly Falkner and Humfrey Melling. In 2003 we sailed together on the US Coast Guard icebreaker Healy and making detailed measurements on ice, water,and bottom sediments. We reported strong southward currents from the Arctic Ocean into Baffin Bay opposing the local winds. Ocean currents were particular strong about 100 meters below the surface on the Canadian coast of Nares Strait. I am still working on these data as they relate to the flux of fresher Arctic waters into the Atlantic Ocean and their climate impacts.

There is history and drama in these places: Hall Basin is named after the leader of the Polaris Expedition, Charles Francis Hall, an American who was likely poisoned in 1871 with arsenic by his German Chief Scientist Dr. Emil Bessel aboard the Polaris beset in ice in Hall Basin. Bessel has a tiny fjord off Greenland named after him, it is located about 10 miles south of Petermann Fjord, named after August Heinrich Petermann, a German cartographer who traveled little himself but mapped much of what others had traveled. Joe Island, named after the Inuit hunter Joe Ebierbing of the Polaris ice drift, is the island that broke the 2010 Petermann Ice Island at the entrance of Petermann Fjord into PII-A and PII-B. The second Inuit hunter of the infamous 1872 drift, Hans Hendrick has Hans Island named after him which is very much in the center of Nares Strait and is currently claimed by both Canada and Denmark.

The Wikipedia entry on the Polaris Expedition has a well-written introduction while the book by Pierre Berton”The Arctic Grail”provides the story along with many other foolish and professional travails to reach the North Pole during the 19th and early 20th centuries.

→ Leave a comment

Posted in Oceanography, Polar Exploration

Tagged , , , ,

Petermann Ice Island(s) 2010 through 2011, Part-1

Posted on January 6, 2012 by | 1 Comment

An ice island 4 times the size of Manhattan spawned from a remote floating glacier in north-western Greenland the first week in August of 2010, but it quickly broke into at least 3-4 very large pieces as soon as it flowed freely and encountered smaller, but real and rocky islands. A beacon placed on the ice transmit its location several times every day. It shows a rapid transit from the frigid, ice-infested Arctic waters off Canada’s Ellesmere, Devon, and Baffin Islands to the balmier coasts of Labrador and Newfoundland:

Track of Petermann Ice Island from Aug.-2010 through Aug.-2011 traveling in shallow water from northern Greenland along Baffin Island and Labrador to Newfoundland.

Initial progress was slow as it took the new ice island almost 30 days to wiggle itself free of the narrow constraints of Petermann Fjord:

Petermann Glacier discharges its large ice island into Nares Strait on Aug.-30, 2010.

As soon as it left its home port, it hit broke hit tiny Joe Island on Sept.-9, 2010 and broke into two pieces, PII-A and PII-B for Petermann Ice Island A and B. Not a good start for a new island setting out to sail all the way to Newfoundland where PII-A arrived a year later, but I am getting ahead of my story.

Petermann Ice Island breaks into two segments on Sept.-9, 2010 as seen in this radar image provided by the European Space Agency. Greenland is at the bottom right, Canada top left, the Arctic Ocean is at the top right.

Once in Nares Strait both ice islands experienced a very strong and persistent ocean current. PII-A, about 1.5 the size of Manhattan went first followed by the larger (about 2.5 Manhattans) and thicker PII-B. Their tracks follow each other closely and they almost kiss on Oct.-8, 2010 when both are caught in the same eddy or meander of a prominent coastal current flowing south along Ellesmere and Devon Islands.

Pieces of Petermann Ice Island on Oct.-8, 2010 off southern Ellesmere Island about 600-km to the south of their origin. RadarSat imagery is courtesy of Luc Desjardins of the Canadian Ice Service, Government Canada.

Within a week the larger 136 km^2 piece PII-B breaks into three pieces of 93.5, 28.9, and 11.3 km^2 by Oct.-16 while PII-A stays largely intact at 73.6 km^2. These are all very large islands, the land area of Manhattan is about 60 km^2 for comparison. Some of these pieces approach the coast, some become grounded for a few days to a few weeks, some break off smaller pieces and spawn massive ice bergs that are not always visible from space. PII-A enters Lancaster Sound a week ahead of PII-B on Nov.-14, but exits it within 2 weeks:

Multiple pieces spawned from Petermann Ice Island as seen by RadarSat on Nov.-26 and Nov.-28, 2010 composited and anotated by Luc Desjardins of the Canadian Ice Service, Government Canada.

Notice also the evolution of a string of segments that Luc Desjardins of the Canadian Ice Service identified as pieces from Petermann Glacier. Glacier ice has a darker radar backscatter signature than the sea ice around it. All these pieces eventually enter the Baffin Island Current, a prominent large ocean current that extends from the surface to about 200-300 m depth. The Petermann pieces are moved mostly by ocean currents, not winds, because there is more drag on the submerged pieces of the 40-150 meter thick glacier ice. In contrast, the much thinner sea ice is mostly driven by the winds. This is also the reason one often finds areas in the lee of icebergs and islands free of older ice which is swept away by the winds as the iceberg moves slower as it is driven by deeper ocean currents. I will talk more of these in a later post.

As part of a large oceanography program in northern Baffin Bay and Nares Strait in 2003, we collected ocean temperature, salinity, chemistry, and current data along lines roughly perpendicular to both Baffin Island in the west and Greenland in the east along with the trajectory of PII-A in the fall of 2010 (red dots) and the almost identical track of a much smaller ice island from Petermann Glacier that passed the area in 2008:

Map of the study area with trajectory of a 2010 (red) and 2008 (grey) beacons deployed on Petermann Glacier ice islands over topography along with CTD station locations (circles) and thalweg (black line). Nares Strait is to the north of Smith Sound.

I will talk about these data and the subsequent tracks of PII-A and PII-B from 2010 into 2011 in Part-2 of this summary on how the first of this piece (PII-A) arrived off coastal Newfoundland in the late summer of 2011. Rest assured that there are many more pieces coming to coastal Labrador and Newfoundland in 2012 and 2013 where they put on a majestic display of abundant icebergs such as this last remnant of PII-A as seen from the air on Nov.-2, 2011 in Notre Dame Bay, Newfoundland.

Last surviving fragments of PII-A on Nov.-2, 2011 from a survey by air of southern Notre Dame Bay conducted by Canadian Ice Service, Government Canada..

→ 1 Comment

Posted in Ice Island, Oceanography, Petermann Glacier

Tagged , , , , ,