Tag Archives: Greenland

Two Years Ocean Observing Below Petermann Glacier Greenland

A year ago today I last set foot on Petermann’s floating ice shelf. The 28th of August 2016 was a drizzly, cloudy day with water running over the surface of the glacier in small streams emptying into larger streams to form small rivers that merged into larger channels carved into the ice. Two years ago Keith Nichols and I set-up a weather station atop the glacier. Many friends helped. We connected copper wires, ocean sensors, and a surface station to collect data from sensors 100-m below the ice in 800-m deep water. The small 2015 project of opportunity keeps giving us hourly ocean data. I am still stunned by our luck and technology.

My Petermann story started in 2010 when a first Manhattan-sized ice cube broke off the glacier. Two days after a University of Delaware press release, the US Congress asked me to appear before one of its inquiring committees. I humbly acknowledged how little I knew then, but everyone else knew even less. In 2012 another Manhattan-sized glacier piece broke off. While satellite a image shows what happens, only hard ocean data and modeling explains why it happens. Two research proposals were rejected, sadly, to probe ocean physics with carefully designed experiments, but in 2016 Alan Mix invited me to an expedition to Petermann aboard the Swedish icebreaker Oden. I gladly accepted, but I wanted to contribute something. That “something” became the Petermann Glacier Ocean Weather Observatory.

Alan needed holes drilled through the 100-m to 400-m thick glacier. Actually, he needed mud from 800 meters below the glacier. Keith Nichols of the British Antarctic Survey drilled those holes for Alan and collected the mud. My plan was to recycle the hole, that is, we dropped kevlar line, copper wire, and ocean sensors into the ocean and connected all to a weather station. David Huntley and I designed the system that included an Iridium satellite phone. Iridium phone calls ceased in February 2016, but a “service call,” that is, a helicopter site visit fixed the station. Chris Mooney and Whitney Shefte told the story for the Washington Post on 30 December 2016.

Ocean temperature at 95-m, 300-m, and 450-m below the sea surface as well as pressure at the bottom sensor near 810-m depth (~810 dbar pressure) updated through 27 August 2017.

The graph shows the entire 2-year long data record. Each gray vertical bar indicates a month between July 2015 and December 2017. The top record shows ocean temperatures just below the floating glacier ice. It was a surprise to see the data change from -0.3 Celsius to -1.6 degrees Celsius. The latter is close to the freezing point of salt water. Hence I interpret low-temperature events as meltwater pulse that swoosh past our sensor.

At 300-m we find a smaller range of temperatures near +0.1 degrees Celsius. Note the steady increase of temperature. Fluctuations are similar, but their absolute values increase with time. The linear warming trend becomes clear at 450-m depth, because the fluctuations diminish, but the warming does not. Temperatures at all depths increased over the entire two years of hourly observations.

The pressure record of the bottom-most sensor on the kevlar line perplexes me: During the first year the sensor slides into deeper water, because the kevlar stretches as all lines do when weighted down. In July 2016 the sensor sharply rises by almost 3 meters from 810.5 to 808.5 dbar to just as rapidly drop again to the 810.5 dbar value. The same feature occurs in the summer of 2017 also. It relates to the summer melt season, but how? I do not know.

The 2-year record is not perfect as the many gaps indicate. These result from electronic and mechanical failures that, I feel, are caused by long and harsh winters when temperatures dropped below -40 degrees Celsius or Fahrenheit. These cold temperatures challenge the best batteries during the 4-5 months of total darkness. On 20. December 2016 our batteries ran out and shut down the station. The sun revived our data gathering when the solar panels recharged batteries in March 2017.

The glacier also melts about 1-2 meters at the surface each summer. This surface melt tilted and almost crashed the station that we repaired last year today. In 2015 we had 2-m of pipe to fix into the glacier ice. In 2016 we replaced this with a 4-m pole that should survive two year’s of surface melt, I hope.

There are many, many people who all contributed in ways both small and large. It takes a village to raise a station on Greenland:

Is Petermann Gletscher Breaking Apart this Summer?

I am disturbed by new ocean data from Greenland every morning before breakfast these days. In 2015 we built a station that probes the ocean below Petermann Gletscher every hour. Data travels from the deep ocean via copper cables to the glacier surface, passes through a weather station, jumps the first satellite overhead, hops from satellite to satellite, falls back to earth hitting an antenna in my garden, and fills an old computer.

A 7-minute Washington Post video describes a helicopter repair mission of the Petermann data machine. The Post also reported first result that deep ocean waters under the glacier are heating up.

Sketch of Petermann Gletscher’s ice shelf with ocean sensor stations. The central station supports five cabled sensors that are reporting hourly ocean temperatures once every day. Graphics made by Dani Johnson and Laris Karklis for the Washington Post.

After two years I am stunned that the fancy technology still works, but the new data I received the last 3 weeks does worry me. The graph below compares ocean temperatures from May-24 through June-16 in 2017 (red) and 2016 (black). Ignore the salinity measurements in the top panel, they just tell me that the sensors are working extremely well:

Ocean temperature (bottom) and salinity (top) at 450-m depth below Petermann Gletscher from May-25 through June-16 2017 (red) and 2016 (black). Notice the much larger day-to-day temperature ups and downs in 2017 as compared to 2016. This “change of character” worries me more than anything else at Petermann right now.

The red temperature line in the bottom panel is always above the black line. The 2017 temperatures indicate waters that are warmer in 2017 than in 2016. We observed such warming for the last 15 years, but the year to year warming now exceeds the year to year warming that we observed 10 years ago. This worries me, but three features suggest a new ice island to form soon:

First, a new crack in the ice shelf developed near the center of the glacier the last 12 months. Dr. Stef Lhermitte of Delft University of Technology in the Netherlands discovered the new crack two months ago. The new rupture is small, but unusual for its location. Again, the Washington Post reported the new discovery:

New 2016/17 crack near the center of Petermann Gletscher’s ice shelf as reported by Washington Post on Apr.-14, 2017.

Second, most Petermann cracks develop from the sides at regular spaced intervals and emanate from a shear zone at the edge. Some cracks grow towards the center, but most do not. In both 2010 and 2012 Manhattan-sized ice islands formed when a lateral crack grew and reached the central channel. The LandSat image shows such a crack that keeps growing towards the center.

Segment of Petermann Gletscher from 31 May 2017 LandSat image. Terminus of glacier and sea ice are at top left.

And finally, let’s go back to the ocean temperature record that I show above. Notice the up and down of temperature that in 2017 exceeds the 2016 up and down range. Scientists call this property “variance” which measures how much temperature varies from day-to-day and from hour-to-hour. The average temperature may change in an “orderly” or “stable” or “predictable” ocean along a trend, but the variance stays the same. What I see in 2017 temperatures before breakfast each morning is different. The new state appears more “chaotic” and “unstable.” I do not know what will come next, but such disorderly behavior often happens, when something breaks.

I fear that Petermann is about to break apart … again.

Only in Thule Greenland

… do you find a machinist working metal to take photos while I do oceanography the old-fashioned way by pulling up 100 meters of kevlar line to recover an ocean probe.

Wolstenholme Fjord March-26, 2017. [Photo by Mogens Werth Christensen]

The data were subsequently used by ocean acousticians to test speed of sound propagation as part of an NSF project on testing an underwater communication system to move data from A to B via C or D. The automated weather station reports ocean temperature and saltiness as well at

http://ows.udel.edu/ice

Web-site is low-bandwidth to be used operationally by Air Force personnel in Greenland and local communities where internet access and speeds are severely limited.

Greenland Oceanography by Sled and Snowmobile

Wind chill matters in Greenland because one must see and breath. This implies exposed skin that will hurt and sting at first. Ignoring this sting for a few minutes, I notice that the pain goes away, because the flesh has frozen which kills nerves and skin tissue. The problem becomes worse as one drives by snowmobile to work on the sea ice which I do these days almost every day.

Navigating on the sea ice by identifying ice bergs with LandSat imagery. The imagery also shows polynyas and thin ice in the area. [Photo Credit: Sonny Jacobsen]

Mar.-22, 2017 LandSat image of study area with Thule Air Base near bottom right, Saunders Island in the center. Large red dots are stations A, B, and C with Camp-B containing weather station, shelter, and first ocean mooring. My PhD student Pat Ryan prepared this at the University of Delaware.

My companion on the ice is Sonny Jacobsen who knows and reads the land, ice, and everything living on and below it. He teaches me how to drive the snowmobile, how to watch for tracks in the snow, how to pack a sled, and demonstrates ingenuity to apply tools and materials on-hand to fix a problem good enough to get home and devise a new and better way to get a challenging task done. Here he is designing and rigging what is to become our “Research Sled” R/S Peter Freuchen, but I am a little ahead of my story:

Sonny Jacobsen on Mar.-27, 2017 on Thule Air Base building a self-contained sled for ocean profiling.

First we set up a shelter in the center of what will hopefully soon become an array of ocean sensors and acoustic modems to move data wirelessly through the water from point A in the north-west via point B to point C. Point C will become the pier at Thule Air Base while the tent is at B that I call Camp-B:

Ice Fishing shelter to the north-east of Saunders Island seen to the left in the background.

Next, we set up an automated weather station (AWS) next to this site, because winds and temperatures on land next to hills, glaciers, and ice sheets are not always the same 10 or 20 km offshore in the fjord. It is a risk-mitigating safety factor to know the weather in the study area BEFORE driving there for 30-60 minutes to spend the day out on the ice. It does not hurt, that this AWS is also collecting most useful scientific data, but again, I am slightly ahead of my story:

Weather station with shelter at Camp-B with the northern shores of Wolstenholme Fjord in the background. Iridium antenna appears just above the iceberg on the sidebar of the station. Winds are measured at 3.2 m above the ground.

With shelter and weather station established and working well, we decided to drill a 10” hole through 0.6 m thin ice to deploy a string of ocean instruments from just below the ice bottom to the sea floor 110 m below. Preparing for this all friday (Mar.-24), we deploy 22 sensors on a kevlar line of which 20 record internally and must be recovered while 2 connect via cables to the weather station to report ocean temperature and salinity along with winds and air temperatures. It feels a little like building with pieces of Lego as I did as a kid. Engineers and scientists, perhaps, are trained early in this sort of thing.

Weather station with ocean mooring (bottom right) attached with eastern Saunders Island in the background on Sunday Mar.-26, 2017.

Sadly, only the ocean sensor at the surface works while the one at the bottom does not talk to me. I can only suspect that I bend a pin on the connector trying to connect very stiff rubber sealing copper pins from the cable with terminations equally stiff in the cold, however, there are other ways to get at the bottom properties albeit with a lot more effort … which brings me to R/S Peter Freuchen shown here during its maiden voyage yesterday:

R/S Peter Freuchen in front of 10” hole (bottom right) for deployment of a profiling ocean sensor. The long pipes looking like an A-frame on a ship become a tripod centered over the hole with the electrical winch to drive rope and with sensors (not shown) over a block into the ocean. This was yesterday Mar.-28, 2017 on the way from Camp-B back to Thule Air Base.

The trial of this research sled was successful, however, as all good trials, it revealed several weaknesses and unanticipated problems that all have solutions that we will make today and tomorrow. The design has to be simple to be workable in -25 C with some wind and we will strip away layers of complexities that are “nice to have” but not essential such as a line counter and the speed at which the line goes into the water. There can not be too many cables or lines or attachments, because any exposure to the elements becomes hard labor. This becomes challenging with any gear leaving the ocean (rope, sensors) and splattering water on other components. Recall that ocean water is VERY hot at -1.7 C relative to -25 C air temperatures. This means that ANYTHING from the ocean will freezes instantly when in contact with air. Efficiency and economy matter … as does body heat to keep critical sensors and batteries warm.

A big Thank-You to Operation IceBridge’s John Woods for something related to this post that I wish not to advertise 😉

Preparing Ocean Work outside Thule Air Base

I am heading to North Greenland in 3 days time to work where temperatures will be close to -20 F. The ocean is covered by 3-4 feet of sea ice that is frozen to land. We will drill lots of ice holes to deploy ocean sensors that will connect via cables to weather stations and satellite phone. Fancy $20,000 GPS units will measure the tides across the fjord and provide a group of future Naval officers a reference for their fancy electronic gear to measure sea ice thickness remotely by walking and comparing results to those obtained from planes overhead. Cool and cold fun.

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The ocean pier at Thule Air Base in Greenland in March 2017. The view is towards the north-west along my proposed mooring line [Photo Credit: Sean Baker]

There has been much packing and shipping the last weeks, about 2300 lbs to be precise,which made my body stiff and sore. Another way to hurt my aging body was to learn shotgun shooting for the unlikely polar bear encounter on the sea ice. My shoulder still hurts from the recoil blasts of the 12 gauge pump-action gun with 3” long cartridges that included a 1 oz. lead slug. I also tested a cot and sleeping bag that will be with me on the ice for emergencies. The night in my garden a few days ago was cozy, but the cot required an insulation mattress, as it was too close to the ground. It was rough sleeping, because of unexpected noises not cold, but I did sleep some and woke up when the sun came up.

Cot, air mattress, and down sleeping bag testing in my garden after a rough night.

Cot, air mattress, and down sleeping bag testing in my garden after a rough night.

The clear skies over Thule during the 2 weeks that the sun is up again also gave me the first Landsat image. It shows the landfast sea ice, but it also shows its very limited extend as very thin ice and perhaps even open water occurs while the winds blow along the coast from the north. This cold wind moves the mobile sea ice offshore to the west thus opening up the oceans that will promptly freeze, however, the back ocean still shows under the inch-thin new ice:

Wolstenholme Fjord as seen by LandSat on Feb.-27, 2017. The line with the red dots extends from Thule pier seaward towards the north-west. Note the dark spot near the left-top corner that shows thin new ice or even open water. White contours are ocean depths in meters.

Wolstenholme Fjord as seen by LandSat on Feb.-27, 2017. The line with the red dots extends from Thule pier seaward towards the north-west. Note the dark spot near the left-top corner that shows thin new ice or even open water. White contours are ocean depths in meters.

This thin new ice is the limit of where I expect to be working. After measuring ice thickness directly via drilling through the ice, my first measurement will be that of how temperature and salinity varies from under the ice to the bottom of the ocean.

Working on the sea ice off northern Greenland [Photo credit, Steffen Olsen]

Working on the sea ice off northern Greenland [Photo credit, Steffen Olsen]

Danish friends do this routinely about 60 miles to the north where they work out of the Inughuit community of Qaanaaq, but Inglefield Fjord is much deeper and connects to warm Atlantic waters from the south that, I believe, we do not have in Wolstenholme Fjord. Hence I expect much less heat inside Wolstenholme Fjord and perhaps a different response of three glaciers to ocean forcing. This theory does not help me much as I will have to lower instruments via rope and a winch into the water. How to attach rope to instruments and winch? Knots.

I am very poor at making knots as my hand-eye co-ordination and memory is poor. So I spent some time this week to learn about knots such as

that should work on my braided Kevlar lines that I connect to shackles

Fancy knots on shackles in my home office ... yes, Peter Freuchen is on the bookshelf, too.

Fancy knots on shackles in my home office … yes, Peter Freuchen is on the bookshelf, too.

There are always devils in the many details of field work. Another worry is that my 10” ice-drill is powered by 1 lbs bottles of propane. It is not possible to send these camping propane canisters via air, but larger 20 lbs tanks exist in Thule for grill cooking at the NSF dormitory where I will be staying. So I also will have to learn how to fill the smaller container from the large one. Just ordered another adaptor from Amazon to travel with me on my body to do this.

I am both terribly nervous and excited about the next 6 weeks. This is my first time working on the ice, because before I have always been on icebreakers in summer. These past Arctic summer expeditions on ships created an unreal and distant connection that, I hope, will be shattered by this spring. I will get closer to the cold and icy seas that are my passion. Oceanography by walking on water … ice.