Category Archives: Arctic Glacier

Petermann Gletscher and Greenland Climate Change

Multi-media story of two old-style scientists on a Greenland data rescue mission. Keith (Nicholls) and I were joined by Chris Mooney and Whitney Shefte of the Washington Post who just posted

Testifying before the US Congress back in 2010, I refused to endorse the view that a first large calving at Petermann Gletscher in North Greenland was caused by global warming. Additional events and analyses of new data and old data, however, convinced me that climate change forces Petermann Gletscher into a new and unknown state.

Oceanography below Petermann Gletscher for 400 Days

Ocean data from 810 meters below sea level under one of Greenland’s last remaining ice shelves arrives every 3 hours at my laptop via a 3-conductor copper cable that passes through 100 meter thick ice to connect to a weather station that via a satellite phone system connects to the rest of the world. This Ocean-Weather station on the floating section of Petermann Gletscher has reported for 400 days today. I am still amazed, stunned, and in awe that this works.

The station started 20th August of 2015 as a small part of a larger joint US-Swedish expedition to North Greenland after friends at the British Antarctic Survey drilled holes through the Empire-State-Building thick ice shelf. It is powered by two 12 Volt car batteries that are recharged by two solar panels. When the sun is down, the car batteries run the station as in winter when temperatures reached -46 C. When the sun is up, the solar cells run the station and top off the batteries. The voltage during the last 400 days shows the “health” of the station:

Battery voltage at the Petermann Ocean-Weather Station from Aug.-20, 2015 through  Sept.-23, 2016. The polar night is indicated by slowly declining voltage near 12 V while during the polar day voltage is near 14 V with oscillations in spring and fall during the transition from 24 hours of darkness to 24 hours of sun light.

Battery voltage at the Petermann Ocean-Weather Station from Aug.-20, 2015 through Sept.-23, 2016. The polar night is indicated by slowly declining voltage near 12 V while during the polar day voltage is near 14 V with oscillations in spring and fall during the transition from 24 hours of darkness to 24 hours of sun light.

There is an unexplained outage without data from February 12-25 (Day 175-189) which happened a day after the first data logger shut down completely without ever recovering. Our station has 2 data loggers: A primary unit controls 2 ocean sensors, atmospheric sensors, and the Iridium satellite communication. The secondary unit controls 3 ocean sensors and the GPS that records the moving glacier. Remote access to the secondary logger is via the primary, however, each logger has its own processors, computer code, and back-up memory card.

Inside of University of Delaware command and control of five ocean sensors and surface weather station. Two data loggers are stacked above each other on the left.

Inside of University of Delaware command and control of five ocean sensors and surface weather station. Two data loggers are stacked above each other on the left.

The primary logger failed 11th February 2016 when we received our last data via Iridium satellites until Keith Nicholls and I visited the station 27th and 28th August 2016 via helicopter from Thule, Greenland. Since I could not figure out what went wrong sitting on the ice with the helicopter waiting, I spent a long night without sleep to swap the data logger with a new and tested unit. I rewired sensors to new data logger, switched the Iridium modem, transceiver, and antenna, changed the two car batteries, and now both data loggers with all five ocean sensors have since reported faithfully every 3 hours as scheduled as seen at

http://ows.udel.edu

Lets hope that the station will keep going like as it does now.

The major discovery we made with the ocean data are large and pronounced pulses of fresher and colder melt waters that swosh past our sensors about 5 and 25 meters under the glacier ice. These pulses arrive about every 14 days and this time period provides a clue on what may cause them – tides. A first descriptive report will appear in December in the peer-reviewed journal Oceanography. Our deeper sensors also record increasingly warmer waters, that is, we now see warm (and salty) waters under the glacier that in 2015 we saw more than 100 km to the west in Nares Strait. This suggests that the ocean under the glacier is strongly coupled to the ambient ocean outside the fjord and vice versa. More on this in a separate future posting.

Time series of salinity (top) and potential temperature (bottom) from four ocean sensors deployed under the ice shelf of Petermann Gletscher from 20th of August 2015 through 11th of February 2016. Temperature and salinity scales are inverted to emphasize the vertical arrangements of sensors deployed at 95m (black), 115 (red), 300 m, and 450 m (blue) below sea level. Note the large fortnightly oscillations under the ice shelf at 95 and 115 m depth in the first half of the record. [From Muenchow et al., 2016]

Time series of salinity (top) and potential temperature (bottom) from four ocean sensors deployed under the ice shelf of Petermann Gletscher from 20th of August 2015 through 11th of February 2016. Temperature and salinity scales are inverted in order to emphasize the vertical arrangements of sensors deployed at 95m (black), 115 (red), 300 m, and 450 m (blue) below sea level. Note the large fortnightly oscillations under the ice shelf at 95 and 115 m depth in the first half of the record. [From Muenchow et al., 2016]

P.S.: The installation and year-1 analyses were supported by a grants from NASA and the Jet Propulsion Laboratory, respectively, while the current work is supported by NSF for the next 3 years. Views and opinions are mine and do not reflect those of the funding agencies.

The Ice Shelf of Petermann Gletscher, North Greenland and its ocean below: Introductions

“In 1921 owing to starvation I had to go directly from Cape Heiberg-Juergensen to our cache at Cape Agassiz … during this journey the greater part of the glacier was mapped.” — Lauge Koch, 1928

Traveling by dog sled, Geologist Lauge Koch mapped Petermann Gletscher in 1921 after he and three Inuit companions crossed it on a journey to explore northern North Greenland. They discovered and named Steensby, Ryder, and H.C. Ostenfeld Glaciers that all had floating ice shelves as does Petermann (Ahnert, 1963; Higgins, 1990). In Figure 1 I reproduce the historic map of Koch (1928) that also contains his track in in 1917 and 1921 both across the terminus and across its upstream ice stream. In 1921 all four starved travelers returned safely after living off the land. Four years earlier, however, they were not so lucky: two traveling companions died on a similar journey in 1917 (Rasmussen, 1923).

Maps of Petermann Gletscher by Lauge Koch from 1917 and 1921 dog sleds and 2015 from MODIS-Terra.

Only 20 years after Lauge Koch’s expeditions by dog sled, air planes and radar arrived in North Greenland with the onset of the Cold War. The Arctic Ocean to the north became a battle space along with its bordering land and ice masses of northern Greenland, Ellesmere Island, Canada, Alaska, and Siberia. Weather stations were established in 1947 at Eureka by aircraft and in 1950 at Alert by US icebreaker to support military aviation (Johnson, 1990). In 1951 more than 12,000 US military men and women descended on a small trading post called Thule that Knud Rasmussen and Peter Freuchen had established 40 years earlier to support their own and Lauge Koch’s dog-sled expeditions across Greenland (Freuchen, 1935). “Operation Blue Jay” built Thule Air Force Base as a forward station for fighter jets, nuclear armed bombers, and early warning radar systems. The radars were to detect ballistic missiles crossing the Arctic Ocean from Eurasia to North America while bombers were to retaliate in case of a nuclear attack from the Soviet Union.

An F-102 jet of the 332d Fighter-Interceptor Squadron at Thule AFB in 1960. [Credit: United States Air Force]

An F-102 jet of the 332d Fighter-Interceptor Squadron at Thule AFB in 1960. [Credit: United States Air Force]

About another 60 years later, the jets, the bombers, and the communist threat were all gone, but the Thule Air Force Base is still there as the gateway to North Greenland. It is also the only deep water port within a 1,000 mile radius where US, Canadian, Danish, and Swedish ships all stop to receive and discharge their crews and scientists. Since 2009 Thule AFB also serves as the northern base for annual Operation IceBridge flights over North Greenland to map the changing ice sheets and glaciers.

The establishment of military weather stations and airfields in the high Arctic coincided with the discovery of massive ice islands drifting freely in the Arctic Ocean. On Aug.-14, 1946 airmen of the 46th Strategic Reconnaissance Squadron of the US Air Force discovered a moving ice islands with an area of about 200 square that was kept secret until Nov.-1950 (Koenig et al, 1950). Most of these ice islands originated from rapidly disintegrating ice shelves to the north of Ellesmere island (Jeffries, 1992; Copland 2007), however, the first historical description of an ice islands from Petermann Gletscher came from Franz Boas in 1883 who established a German station in Cumberland Sound at 65 N latitude and 65 W longitude as part of the first Polar Year.

Petermann Ice Island of 2012 at the entrance of Petermann Fjord. The view is to the north-west with Ellesmere Island, Canada in the background. [Photo Credit: Jonathan Poole, CCGS Henry Larsen]

Petermann Ice Island of 2012 at the entrance of Petermann Fjord. The view is to the north-west with Ellesmere Island, Canada in the background. [Photo Credit: Jonathan Poole, CCGS Henry Larsen]

Without knowing the source of the massive tabular iceberg the German physicist Franz Boas reported detailed measurements of ice thickness, extend, and undulating surface features of an ice island in Cumberland Sound that all match scales and characteristics of Petermann Gletscher (Boas, 1885). These characteristics were first described by Dr. Richard Croppinger, surgeon of a British Naval expedition in 1874/75 (Nares, 1876). Dr. Croppinger identified the terminus of Petermann Gletscher as a floating ice shelf when he noticed vertical tidal motions of the glacier from sextant measurements a fixed point (Nares, 1876). His observations on tides were the last until a group of us deployed 3 fancy GPS units on the glacier last summer.

These fancy GPS receivers give centimeter accuracy vertical motions at 30 second intervals. Here is what the deployment of 3 such units in August of 2015 gives me:

Vertical (top) and horizontal (bottom) motion of Petermann Gletscher from GPS referenced to a GPS base station on bed rock at Kap Schoubye. Note the attenuation of the tide from 26 km sea ward of the grounding line (red) to at the grounding line (black) and 15 km landward of the grounding line (blue). The horizontal location motion has the mean motion removed to emphasize short-term change over the much, much larger forward motion of the glacier that varies from about ~700 (black) to ~1250 meters per year (red).

Vertical (top) and horizontal (bottom) motion of Petermann Gletscher from GPS referenced to a GPS base station on bed rock at Kap Schoubye. Note the attenuation of the tide from 26 km sea ward of the grounding line (red) to at the grounding line (black) and 15 km landward of the grounding line (blue). The horizontal location motion has the mean motion removed to emphasize short-term change over the much, much larger forward motion of the glacier that varies from about ~700 (black) to ~1250 meters per year (red).

We have indeed come a far way during the last 150 years or so. Mapping of remote landscape and icescape by starvation and dog-sled has been replaced by daily satellite imagery. Navigation by sextant and a mechanical clock has been replaced by GPS and atomic clock whose errors are further reduced by a local reference GPS. These fancy units and advanced data processing allow me to tell the vertical difference between the top of my iPhone sitting on a table in my garden from the table.

Working at in the garden at home preparing for field work.

Working at in the garden at home preparing for field work near Petermann Fjord.

P.S.: This is the first in a series of essays that I am currently developing into a peer-reviewed submission to the Oceanography Magazine of the Oceanography Society. The work is funded by NASA and NSF with grants to the University of Delaware.

Ahnert, F. 1963. The terminal disintegration of Steensby Gletscher, North Greenland. Journal of Glaciology 4 (35): 537-545.

Boas, F. 1885. Baffin-Land, geographische Ergebnisse einer in den Jahren 1883 und 1884 ausgeführten Forschungsreise. Petermann’s Mitteilungen Ergänzungsheft 80: 1-100.

Copland, L., D.R. Mueller, and L. Weir. 2007. Rapid loss of the Ayles Ice Shelf, Ellesmere Island, Canada. Geophysical Research Letters 34 (L21501): doi:10.1029/2007GL031809.

Freuchen, P. 1935. Arctic adventures: My life in the frozen North. Farrar & Rinehard, NY, 467 pp.

Higgins, A.K. 1990. North Greenland glacier velocities and calf ice production. Polarforschung 60 (1): 1-23.

Jeffries, M. 1992. Arctic ice shelves and ice islands: Origin, growth, and disintegration, physical characteristics, structural-stratigraphic variability, and dynamics. Reviews of Geophysics 30 (3):245-267.

Johnson, J.P. 1990. The establishment of Alert, N.W.T., Canada. Arctic 43 (1): 21-34.

Koch, L., 1928. Contributions to the glaciology of North Greenland. Meddelelser om Gronland 65: 181-464.

Koenig, L.S., K.R. Greenaway, M. Dunbar, and G. Hattersley-Smith. 1952. Arctic ice islands. Arctic 5: 67-103.

Münchow, A., K.K. Falkner, and H. Melling. 2015. Baffin Island and West Greenland current systems in northern Baffin Bay. Progress in Oceanography 132: 305-317.

Münchow, A., L. Padman, and H.A. Fricker. 2014. Interannual changes of the floating ice shelf of Petermann Gletscher, North Greenland, from 2000 to 2012. Journal of Glaciology 60 (221): doi:10.3189/2014JoG13J135.

Nares, G. 1876. The official report of the recent Arctic expedition. John Murray, London,

Rassmussen, K., 1921: Greenland by the Polar Sea: the Story of the thule Expedition from Melville Bay to Cape Morris Jessup, translated from the Danish by Asta and Rowland Kenney, Frederick A. Stokes, New York, NY, 327 pp.

Thule, Greenland in Sharp Focus

I want to fly like an eagle
To the sea
Fly like an eagle
Let my spirit carry me

Steve Miller Band, 1976

The eagle “sees” the ground, because the twinkling sensation of light tickles her nerves. Today’s cameras work without the twinkle and tickle. They store numbers (digits) that approximate the amount of light passing through the lens. Satellite sensors work the same way. The data they beam to earth give me the soaring feeling of flying like an eagle, but there is more to the bits and bytes and digits sent home from space to our iPhones, laptops, and the internet.

Aerial photo taken Oct.-13, 1860 of Boston, MA by J.W. Black.

Aerial photo taken Oct.-13, 1860 Boston, MA from a balloon by J.W. Black.

The Metropolitan Museum of Art in New York houses the earliest existing aerial photo that was taken from a balloon hovering 600 meters above Boston, Massachusetts. Within a year the American Civil War broke out and this new technology became an experimental tool of war. It advanced rapidly, when air craft replaced the balloon during the First World War. Sharp photos of bombed-out battle and killing fields along the entire Western Front in France were taken by both Allied and German soldiers every day. Placing these photos on a map for efficient analyses of how a land- sea- or ice-scape changes over time, however, was impossible, because photos do not record precise locations.

Modern satellite photos are different. We now have fancy radar beams, computers, and several Global Position Systems (GPS) with atomic clocks to instantly calculation satellite tracks every second. This is why we now can both take photos from space AND map every dot or pixel that is sensed by the satellite moving overhead at 17,000 miles an hour snapping pictures from 430 miles above. The camera is so good that it resolves the ground at about 45 feet (15 meters). This is what such a (LandSat) picture looks like

LandSat photo/map of Thule, Greenland Mar.-17, 2016. The airfield of Thule Air Force Base is seen near the bottom on the right. The island in ice-covered Westenholme Fjord is Saunders Island (bottom left) while the glacier top right is Chamberlin Gletscher.

LandSat photo/map of Thule, Greenland Mar.-17, 2016. The airfield of Thule Air Force Base is seen near the bottom on the right. The island in ice-covered Westenholme Fjord is Saunders Island (bottom left) while the glacier top right is Chamberlin Gletscher.

Everyone can download these photos from the United States Geological Survey which maintains a wonderful photo and data collection archive at

http://earthexplorer.usgs.gov

but the tricky part is to turn these images or photos into maps which I have done here. More specifically, I wrote a set of c-shell and nawk scripts along with Fortran programs on my laptop to attach to each number for the light sensed by the satellite (the photo) another two numbers (the map). These are latitude and longitude that uniquely fix a location on the earth’s surface. A “normal” photo today has a few “Mega-Pixels,” that is, a few million dots. Each scene of LandSat, however, has about 324 million dots. This is why you can discern both the runways of Thule Air Force Base at 68 degrees 45′ West longitude and 76 degrees 32′ North latitude. The pier into the ice-covered ocean is just a tad to the south of Dundas Mountain at 68:54′ W and 76:34′ N. A scale of 5 kilometers is shown at the top on the right. For spatial context, here is a photo of the pier with the mountain in the background, that is, the object shown in the photo such as mountain, ship, and Helen serves a rough, but imprecise reference:

Dr. Helen Johnson in August 2009 on the pier of Thule AFB with CCGS Henry Larsen and Dundas Mountain in the background. [Credit: Andreas Muenchow]

Dr. Helen Johnson in August 2009 on the pier of Thule AFB with CCGS Henry Larsen and Dundas Mountain in the background. [Credit: Andreas Muenchow]

This photo shows the airfield and Saunders Island

Thule AFB with its airport, pier, and ice-covered ocean in the summer. The island is Saunders Island. The ship is most likely the CCGS Henry Larsen in 2007. [Credit: Unknown]

Thule AFB with its airport, pier, and ice-covered ocean in the summer. The island is Saunders Island. The ship is most likely the CCGS Henry Larsen in 2007. [Credit: Unknown]

The satellite image of the ice-covered fjord with Thule, Saunders Island, and Chamberlin Gletschers shows a richly texture field of sea ice. The sea ice is stuck to land and not moving except in the west (top left) where it starts to break up as seen by the dark gray piece that shows ‘black’ water peeking from below a very thin layer of new ice. There is also a polynya at 69:15′ W and 76:39′ N just to the south of an island off a cape. A polynya is open water that shows as black of very dark patches. A similar albeit weaker feature also shows to the east of Saunders Island, but it is frozen over, but the ice there is not as thick as it is over the rest of Westenholme Fjord. I suspect that larger tidal currents over shallow water mix ocean heat up to the surface to keep these waters covered by water or dangerously thin ice. There are also many icebergs grounded in the fjord. They cast shadows and from the length of these shadows one could estimate their height. Here is another such photo from 2 days ago:

LandSat photo/map of Thule, Greenland Mar.-21, 2016. The airfield of Thule Air Force Base is seen near the bottom on the right. The island in ice-covered Westenholme Fjord is Saunders Island (bottom left) while the glacier top right is Chamberlin Gletscher.

LandSat photo/map of Thule, Greenland Mar.-21, 2016. The airfield of Thule Air Force Base is seen near the bottom on the right. The island in ice-covered Westenholme Fjord is Saunders Island (bottom left) while the glacier top right is Chamberlin Gletscher.

I am using the satellite data and maps here to plan an experiment on the sea ice of Westenholme Fjord. Next year in March/April I will lead a team of oceanographers, engineers, and acousticians to place and test an underwater network to send data from the bottom of the ocean under the sea ice near Saunders Island to the pier at Thule and from there on to the internet. We plan to whisper from one underwater listening post to another to communicate over long ranges (20-50 kilometers) via a network of relay stations each operating smartly at very low energy levels. We will deploy these stations through holes drilled through the landfast ice 1-2 meters thick. The work is very exploratory and is funded by the National Science Foundation. Wish us luck, as we can and will use it … along with aerial photography that we turn into maps.

Sun Sets over Petermann Gletscher

Lights are out. Our ocean weather station on a floating glacier of northern Greenland confirms what the U.S. Naval Observatory reports for location 60 degrees and 30 minutes West longitude and 80 degrees and 40 minutes North latitude: As of today the sun is no longer above the horizon and will not rise until 23 February 2016. Total darkness means no solar power for the station that will have to survive on a fancy car battery temperatures as low as -50 degrees centigrade. Last week with the sun still up our station recorded -30.4 degrees celsius about 4 feet above the ice. How long will the station survive on that car battery?

Petermann Gletscher at dawn on 5 Oct. 2015 as captured by NASA Operation IceBridge. Our Ocean Weather Station is in the corner bottom left.

Petermann Gletscher at dawn on 5 Oct. 2015 as captured by NASA Operation IceBridge. Our Ocean Weather Station is in the corner bottom left.

Without power the station does not function, because each sensor, each computer, and each telephone call via the Iridium satellite system requires electricity. Without power I am in the dark about what the station does or what ocean or air temperatures are. Since I do have power at the moment, well, I got new data. For example, there is a voltage that the station sends me …

Voltage at Ocean Weather Station on Petermann Gletscher.

Voltage at Ocean Weather Station on Petermann Gletscher.

… whenever the sun is up, the solar panels recharge the battery and the voltage goes up. As I use electricity, the voltage goes down. Lets ignore a small temperature effect and details on how much electricity we draw at what “amperage.” Instead, lets focus on the regular up and down of voltage for the last 60 days and how it suddenly went flat. The flat line at 12.5 Volts tells me that the sun is down. The station now uses the car battery, but how long will this last? Quick answer is … a day, if I am dumb. Or 150 days, if I am smart. Time will tell, if I made a mistake in either my power budget or my computer code that gives and takes power to a range of sensors. Scary stuff, and my little sister Christina Parsons can attest, how nervous I was, when I uploaded new power-saving software that I wrote from my attic at home to the station in Greenland. The station did take the new software, restarted itself, and works making one data call each day instead of three. Data are still collected every hour, but I save 20% of total power.

Power is something in Watts (40 W Light bulb anyone?) and you have to multiply voltage by current draw (0.5 Amps anyone?) to estimate the power needs of the device drawing 0.5 Amp current at 12 Volts. Incidentally, 0.5 Amps is what the Iridium satellite phone draws when it calls me with new data. Let me check my power budget, if this is true … nope, it only takes 0.365 Amps, so it takes 12 volts times 0.365 Amps equal 4.4 Watts which is about 1/10 of that 40 W light bulb you are looking at, perhaps, or the station we put up: the yellow box is the car battery powering all the gadgets you see and many more you do not:

What I just showed you is the beginning of a power budget that I had to make to get my station through the night, now that there is no more sun for the next 4-5 months. My car batteries are rated to give 110 Watts for an hour, so if I run my 4.4 W satellite phone all the time, I would be out of battery juice after 110 Watt-Hours divided by 4.4 Watts equals 25 hours. That’s bad, real bad, especially since one should not run a car battery to zero and the battery at -30 degrees Celsius may only give me half the power than it would at the more usual 15 degrees Celsius we got outside. The solution to this problem is to use the phone only for a few minutes each day, say 5 minutes. So, since I am using the phone only 5 minutes out of the 1440 minutes that each day has, it takes about 1440 minutes divided by 5 minutes times 25 hours equals 300 days for the phone running 5 minutes each day to run down the battery. Magic this math is not, but it shows how important it is to use resources (electricity) wisely. There are times and places where it is not possible to plug your iPhone into a power outlet. You get the picture … well, here are some that University of Delaware PhD student Peter Washam took who was part of the ice drilling team during last summer’s deployment of the ocean weather station:

So, as of this morning at 4 am Delaware time, the station now in total darkness tells me that the ocean temperatures 700 meters below the 100 meter thick glacier are +0.3 degrees Celsius while air temperatures 2 meters above the ice are -11.1 degrees Celsius. Now what that means to the melting of the glacier by the ocean, I will have to tell you at another time in more detail. These data are the ONLY data from below any glacier to the north of the equator. We are really breaking new ground and are making new discoveries as we go along … as long as there is power. Hopefully there is no dumb mistake in my power budget.

Sun over the horizon of Greenland as seen during NASA's Operation IceBridge Flight in October 2015.

Sun over the horizon of Greenland as seen during NASA’s Operation IceBridge Flight in October 2015.