Category Archives: Petermann Glacier

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.

Petermann Gletscher Ocean Station Revisited

Standing on floating Petermann Gletscher last sunday, I called my PhD student Peter Washam out of bed at 5 am via our emergency Iridium phone to check the machine that Keith Nicholls and I had just repaired. We had prepared for this 4 months and quickly established that a computer in Delaware could “talk” to a computer in Greenland to receive data from the ocean 800 m below my feet on a slippery glacier. For comparison the Empire State Building is 480 m high. The closest bar was 5 hours away by helicopter at Thule Air Force Base from where Keith and I had come.

Cabled ocean observatory linked to a University of Delaware weather station on Petermann Gletscher, Greenland on 28 August 2016. View is to the north.

Refurbished ocean observatory linked via cables to a University of Delaware weather station on Petermann Gletscher, Greenland on 28 August 2016. View is to the north.

Remote Petermann Gletscher can be reached by helicopter only of one prepares at least two refueling stations along the way. Anticipating a potential future need, we had placed 1300 and 1600 liters of A1 jet fuel at two points from aboard the Swedish icebreaker Oden in 2015. The fuel was given to Greenland Air with an informal agreement that we could use the fuel for a 2016 or 2017 helicopter charter. Our first pit stop looked like this on the southern shores of Kane Basin

Refueling stop on north-eastern Inglefield Land on 27 August 2016. Air Greenland Bell-212 helicopter in the background, view is to the north.

Refueling stop on southern Washington Land on 27 August 2016. Air Greenland Bell-212 helicopter in the background, view is to the south towards Kane Basin.

Helicopter flight path on 27/28 August 2016 to reach Petermann Gletscher (PG) via southern (Fuel-S) and northern (Fuel-N) fuel stops in northern Inglefield and southern Washington Land, respectively. Background color is ocean bottom depth in meters.

Helicopter flight path on 27/28 August 2016 to reach Petermann Gletscher (PG) via southern (Fuel-S) and northern (Fuel-N) fuel stops in northern Inglefield and southern Washington Land, respectively. Background color is ocean bottom depth in meters.

Upon arrival at the first (northern-most) Peterman Gletscher (PG) station we quickly confirmed our earlier suspicion that vertical motion within the 100 m thick glacier ice had ruptured the cables connecting two ocean sensors below the ice to data loggers above. We quickly disassembled the station and moved on to our central station that failed to communicate with us since 11 February 2016. Keith predicted that here, too, internal glacier motions would have stretched the cables inside the ice to their breaking point, however, this was not to be the case.

My first impression of this station was one of driftwood strewn on the beach of an ocean of ice:

Looks can be deceiving, however, and we found no damage to any electrical components from the yellow-painted wooden battery box housing two 12 Volt fancy “car batteries” at the bottom to the wind sensor on the top. Backed-up data on a memory card from one of two data loggers (stripped down computers that control power distribution and data collections) indicated that everything was working. The ocean recording from more than 800 meters below our feet was taken only a few minutes prior. In disbelief Keith and I were looking over a full year-long record of ocean temperature, salinity, and pressure as well as glacier motions from a GPS. This made our choices on what to do next very simple: Repair the straggly looking ocean-glacier-weather station, support it with a metal pole drilled 3.5 m into the glacier ice, and refurbish the adjacent radar station. We went to work for a long day and longer night without sleep.

Selfie on Petermann Gletscher on sunday 28 August 2016 after 33 hours without sleep. Weather station and northern wall of Petermann in the clouds. It was raining, too.

Selfie on Petermann Gletscher on sunday 28 August 2016 after 33 hours without sleep. Weather station and northern wall of Petermann in the clouds. It was raining, too.

When all was done, University of Delaware graduate student Peter Washam did the last check at 5:30 am sunday morning. Since then our Greenland station accepts Iridium phone calls every three hours, sends its data home where I post it daily at

http://ows.udel.edu

The data from this station will become the center piece of Peter’s dissertation on glacier-ocean interactions. Peter was part of the British hot water drilling team who camped on the ice in 2015 for 3 weeks while I was on I/B Oden responsible for the work on the physical oceanography of the fjord and adjacent Nares Strait. Alan Mix of Oregon State University prepared and led the 2015 expedition giving us ship and helicopter time generously to support our work on the ice shelf of Petermann. Saskia Madlener documented the scope of the 2015 work in a wonderful set of three videos

Ocean & Ice – https://vimeo.com/178289799
Rocks & Shells – https://vimeo.com/178379027
Seafloor & Sediment – https://vimeo.com/169110567

A first peer-reviewed publication on this station and its data until 11 February 2016 will appear in the December 2016 issue of the open-access journal Oceanography with the title The Ice Shelf of Petermann Gletscher, North Greenland and its Connection to the Arctic and Atlantic Oceans.

The Ice Shelf of Petermann Gletscher and its Ocean Below: Descriptions

“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

Petermann Fjord connects Petermann Gletscher to Nares Strait which in turn is connected to the Arctic Ocean in north and the Atlantic Ocean in the south (Figure-2). The track of Petermann ice island PII-2010A emphasizes this connection as the 60 meter thick section of the ice island reaches the Labrador Sea in the south within a year after its calving in 2010.

TOS2016-Fig2

PII-2010 left Petermann Fjord on the 9th of September in 2010 when it broke into segments A and B while pivoting around a real island. It flushed out of Nares Strait 10 days later when an ice-tracking beacon was placed to track the ice island. The ~60 m thick segment PII-2010A moved southward with the Baffin Island Current (Münchow et al., 2015) at an average speed of ~ 0.11 m/s past Davis Strait. Remaining on the continental shelf of the Labrador Sea, it passed Boas’ Cumberland Sound, Labrador, and reached Newfoundland in August 2011 when it melted away in a coastal cove about 3000 km from Petermann Fjord (Figure-2).

TOS2016-Fig7

Petermann Gletscher drains about 4% of the Greenland ice sheet via a network of channels and streams that extend about 750 km landward from the grounding line (Bamber et al., 2013). The glacier goes afloat at the grounding zone where bedrock, till, and ice meet the ocean waters about 600 meter below sea level (Rignot, 1996).

TOS2016-Fig3

Figure-3 shows a section of surface elevation from a laser altimeter flown on a repeat path along the glacier in April 2013 and May 2014 as part of NASA’s Operation IceBridge. Assuming hydrostatic balance, we also show basal topography below the sea surface that varies from 200 meters at the terminus to 600 meters at the grounding zone near distance zero (Figure-3). The 2013 profile has been shifted seaward by 1.25 km to match the terminus position. Note the close correspondence of large and small crevasses in 2013 and 2014 near 20, 40, and 45 km from the grounding zone.

The seaward shift of the 2013 relative to the 2014 profile implies a uniform glacier speed of about 1180 meters per year. This value is almost identical to the 1170 meters per year that we measure between 20th August of 2015 and 11th February of 2016 with a single-frequency GPS placed about 13 km seaward of the grounding zone as part of the ocean weather observatory.

We compare 2013/14 and 2015/16 velocity estimates in Figure-3 with those obtained from RadarSat interferometry between 2000 and 2008 (Joughin et al., 2010) of which I here only show three:

Figure-3 shows that glacier speeds before 2010 are stable at about 1050 m/y, but increased by about 11% after the 2010 and 2012 calving events. This increase is similar to the size of seasonal variations of glacier motions. Each summer Petermann Gletscher speeds up, because surface meltwater percolates to the bedrock, increases lubrication, and thus reduces vertical friction (Nick et al., 2012). Figure 3 presents summer velocity estimates for August of 2015 from three dual-frequency GPS. The along-glacier velocity profiles measured by these geodetic sensors in the summer follow the shape of the 2000 to 2008 winter record, however, its speeds are about 10% larger and reach 1250 m/y near the grounding zone (Figure 3).

Uncertainty in velocity of these GPS systems is about 1 m/y which we estimate from two bed rock reference stations 82 km apart. Our ice shelf observations are referenced to one of these two semi-permanent geodetic stations. Its location at Kap Schoubye is shown in Figure-1. Data were processed using the GAMIT/TRACK software distributed by MIT following methodology outlined by King (2004) to archive vertical accuracy of 2-3 centimeters which, we show next, is small relative to tidal displacements that reach 2 meters in the vertical.

TOS2016-Fig4

Figure-4 shows the entire 13 day long record of vertical glacier displacement from 30 seconds GPS measurements in August of 2015. The observed range of vertical glacier displacements diminishes from almost 2 meters about 26 km seaward of the grounding zone (GZ+26) via 0.6 meters in the grounding zone (GZ-00) to nil 20 km landward of the grounding zone (GZ-20). Anomalies of horizontal displacement are largest at GZ-00 with a range of 0.2 m (not shown) in phase with vertical oscillations (Figure-4).

More specifically, at GZ+26 we find the ice shelf to move up and down almost 2 meters roughly twice each day. This is the dominant semi-diurnal M2 tide which has a period of 12.42 hours. Notice that for each day there is also a diurnal inequality in this oscillation, that is, the two maximal (minimal) elevations oscillate from a higher to a lower High (Low) water. This is the diurnal K1 tide which has a period of 23.93 hours. And finally, all amplitudes appear modulated by some longer period that appears close to the record length of almost two weeks. This is the spring-neap cycle that is caused by a second semi-diurnal S2 tide that has a period of 12.00 hours. A formal harmonic analysis to estimate the amplitude and phases of sinusoidal oscillations at M2, K1, S2 and many more tidal constituents will be published elsewhere for both Petermann Fjord and Nares Strait. Preliminary results (not shown) reveal that the amplitudes and phases of the tidal signals at GZ+26 are identical to those observed off Ellesmere Island at 81.7 N latitude in both the 19th (Greely, 1888) and 21st century.

Hourly tidal observations at Discovery Harbor taken for 15 days by Greely in 1881 and Peary in 1909.

Hourly tidal observations at Discovery Harbor taken for 15 days by Greely in 1881 and Peary in 1909.

In summary, both historical and modern observations reveal real change in the extent of the ice shelf that moves at tidal, seasonal, and interannual time scales in response to both local and remote forcing at these times scales. Future studies will more comprehensively quantify both the time rate of change and its forcing via formal time series analyses.

P.S.: This is the second in a series of four 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.

References:

Bamber, J.L., M.J. Siegert, J.A. Griggs, S. J. Marshall, and G. Spada. 2013. Palefluvial mega-canyon beneath the central Greenland ice sheet. Science 341: 997-999.

Greely, A.W. 1888. Report on the Proceedings of the United States Expedition to Lady Franklin Bay, Grinnell Land. Government Printing Office, Washington, DC.

Joughin, I., B.E. Smith, I.M. Howat, T. Scambos, and T. Moon. 2010. Greenland flow variability from ice-sheet wide velocity mapping. Journal of Glaciology 56 (197): 415-430.

King, B. 2004. Rigorous GPS data-processing strategies for glaciological applications. Journal of Glaciology 50 (171): 601–607.

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.

Nick, F.M., A. Luckman, A. Vieli, C.J. Van Der Veen, D. Van As, R.S.W. Van De Wal, F. Pattyn, A.L. Hubbard, and D. Floricioiu. 2012. The response of Petermann Glacier, Greenland, to large calving events, and its future stability in the context of atmospheric and oceanic warming. Journal of Glaciology 58 (208): 229-239.

Rignot, E. 1996. Tidal motion, ice velocity and melt rate of Petermann Gletscher, Greenland, measured from radar interferometry. Journal of Glaciology 42 (142): 476-485.

Greenland Calling: Iridium Satellite Phone

I have trouble calling Petermann Gletscher, Greenland where I am collecting ocean data that feeds into a remote weather station. This station is run on a pair of car batteries, because the solar panels do not work until the sun rises again in two months and the next electrical outlet is about 300 miles away. A computer controls power to sensors and a satellite phone. All calls from and to the station are routed via a commercial satellite phone system that consists of about 66 satellites orbiting our planet. They often appear as shooting stars in the night sky that are called Iridium flares. As beautiful as these orbiting satellites are, they have driven me mad.

Screen shot of Iridium satellite orbits observed in real-time from http://www.satflare.com/track.asp?q=iridium

Screen shot of Iridium satellite orbits observed in real-time from http://www.satflare.com/track.asp?q=iridium

Iridium satellite phones and modems connected to computers are the only way to get data from remote areas of the Arctic and Antarctic. Some modems send small text messages called Short-Burst-Data (SBD) while other modems support a true two-way dial-up connection that includes all the hand-shaking of a telephone call. This computer-to-computer calling is more tricky than the person-to-person calls that this system was originally designed for. Working near Petermann Fjord, we had much trouble with even the person-to-person calls. Senator John McCain’s of the U.S. Congress was rudely disconnected, when he called us on the ship while in Sweden working with Government officials. And the Iridium phones on our Swedish icebreaker I/B Oden were thoroughly checked by field technician Robert Holden:

Rob Holden testing Iridium phones above the bridge of I/B Oden.

Robert Holden testing Iridium phones above the bridge of I/B Oden in August of 2015.

The building and coding of this ocean weather station is cool stuff for someone like me who likes Legos, computer games, and hacking electronics. Our Greenland ocean observing system uses both the text message SBD system at two smaller stations and the dial-up system at the larger weather station. The SBD system is great for small burst of data smaller than 1960 bytes per message. The Greenland station makes the call to a ground station that then e-mails the message forward to us. The method is very reliable, but there are small connection gaps that become data gaps.

Inside of University of Delaware command and control of five ocean sensors and surface weather station. Two computers 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 computers are stacked above each other on the left with satellite modem 9522B on bottom left with RS-232 cable connecting to computer (Campbell Scientific CR1000).

In contrast, the dial-up method delivers a gap-free data set, but its bi-polar behavior drives me nuts. There are periods when each scheduled call results in a connection and new data, but there are also periods when each scheduled call fails to connect. Over the last 4 months I made 1450 calls to Greenland. Only 189 of these 1450 calls resulted in a connection. That is a failure rate of 87%. It admittedly includes one desperate day (Sept.-18) when I made a call every 3 minutes and each call failed. This desperation was after a 10-day sequence of failed calls when I lost my cool. There were 86 out of 130 days when a successful connection was made, that’s still a large failure rate of 34%, but there are zero missing data so far. [The station was set up Aug.-20.]

Logs-OWS

The advantage of the fickle dial-up connection is that I only need one connection to recover all data that has been collected since the last successful call. This differs from the SBD text message, where a lost connection means lost data. Furthermore, the connection to the Greenland station is a regular RS-232 connection which acts the same as the iPhone connected to the computer from which I type these lines. Hence software changes are possible, too, as scary as they may be.

Now why is the Iridium connection acting in a such a bi-polar fashion, that is, working like a charm for weeks and months to suddenly shut down completely for days to weeks just as suddenly? My honest answer is that I do not know. Furthermore, nobody really knows for sure. There is some talk in hidden places that Iridium modems or phones “de-register” themselves from the Iridium network, if they do not start a phone call. This is no problem for the SBD message as the Greenland modem always does the calling. It does matter for my dial-up, because the Greenland modem never initiates a call, it only responds when called after the Greenland computer gives it the power to do so. Which brings me to

‘Fake call’
Register_Modem = “ATDT 1234″ & CHR(13) & CHR(10)
SerialOpen (ComRS232,19200,0,0,2000)
Delay (0,1,Sec)
SerialOut (ComRS232,Register_Modem,””,0,0)
SerialClose (ComRS232)

The “fake call” is a software update that tells the Greenland modem to, well, make a fake call. The text string Register_Modem contains a non-existing phone number (I hope) 1234 as well as a carriage return CHR(13) and a line feed CHR(10) and the string is send via SerialOut to the modem that is addressed here as ComRS232 after the serial port between Greenland computer and modem is opened via SerialOpen. Lets see how this works over the next days, weeks, and months. For the first time, I received this morning a response from Greenland that it was “BUSY.” I took this as a good sign …

PostScript: Data look awesome with new, large, and unexpected diurnal variations that started Dec.-8.

Ocean temperature (black) and salinity (red) below Petermann Gletscher from Dec.-6 (Day-340) through Dec.-31 (Day-365). Top panel is just below the glacier ice at 95-m below sea level while bottom panel shows data 810-m below sea level.

Ocean temperature (black) and salinity (red) below Petermann Gletscher from Dec.-6 (Day-340) through Dec.-31 (Day-365). Top panel is just below the glacier ice at 95-m below sea level while bottom panel shows data 810-m below sea level.

Below Petermann Glacier: The First 100 Days

I am still stunned to see data coming to me hourly from below a glacier in northern Greenland while I sip my breakfast coffee. Each and every day for the last 100 days I got my data fix from the Ocean Weather Station that was born 100 days ago. Every morning at 8:15 the station sends me data from 5 ocean sensors below the glacier. A year ago I did not even know that I would be going to northern Greenland with the Swedish icebreaker I/B Oden in the summer of 2015, never mind that we would be able to pull off the engineering challenge to set up the first and only ocean observing system of Greenland. Today, I am over-joyed to report, we got 100 days of data.

IMG_3029

University of Delaware PhD student Peter Washam at the Ocean-Weather station on Petermann Gletscher after final installation 2015-Aug.-20, 17:00 UTC at 80 39.9697 N and 60 29.7135 W.

It all started when a French PhD student approached me at a scientific meeting in San Francisco last December. Céline is a now a doctor of oceanography, but at the time she was not. At the meeting Dr. Céline Heuzé of the University of Gothenburg in Sweden asked me for data and insights on how the ocean circulation in Nares Strait worked, so that she could connect results from planned field work in northern Greenland to her science interests in the Labrador Sea more than 1000 miles to the south. She also introduced me to Dr. Anna Wåhlin and the three of us got very excited about Petermann Fjord, Sweden, and polar oceanography. Here we are in Sweden preparing and off Greenland working:

A few weeks prior the US government and Sweden had just agreed to work together on a joint expedition to Petermann Fjord in northern Greenland. Friends at Oregon State University needed a ship to collect data with which to reconstruct and understand changes of the land- sea-, and ice-scape of North Greenland during the last 10,000 to 50,000 years. They wanted to uncover where past glaciers were located and where sea level was at that time. For this, they needed many sediment cores from the adjacent ocean, fjord, and below the floating glacier. Today this glacier is as thick as the Empire State Building in Manhattan is high. The British Antarctic Survey (BAS) agreed to drill the holes, collect the sediment samples, and take a profile of ocean properties from below the glacier ice to the bottom of the ocean. They estimated it would take about 5 days to drill each hole. Our idea was to use these holes to keep sensors, computers, and satellite phones in place to collect hourly data into the future as long as possible … 100 days so far.

After the Dec.-2014 San Francisco meeting we decided to use these holes to measure ocean temperature, salinity, and pressure for as long as the batteries would last, about 3-4 years, but I had neither money, cables, data logging computers, nor satellite phones to do any of this, only the ocean sensors. When I told Keith Nicholls of BAS about the idea and my predicament, he said that he could find some computers and satellite phones from experiments he had done in Antarctica. I then said that I would organize cables, a weather station, and some funds to pay for it.

A crowd-funding experiment in February failed to generate funds, but NASA came to the rescue by opening a way to compete for the needed $60,000 to cover the cost of hardware, travel, and satellite phone charges. The funds allowed us to ship about 1200 pounds of gear from Delaware to Sweden where it had to be loaded onto the ship in May of 2015. We did not have much time to built the system and had no time left to test it. Two drums of cable arrived with only 5 hours to spare before the ship left Sweden in June for Greenland. We met the ship in Thule, Greenland in July.

Fast-forward to the 20th of August 2015 when our ocean observing system went into the salty ocean waters below Petermann Gletscher. The surface weather station with satellite connections was deployed 10 days earlier to test satellite communications and collect weather data for Oden’s extensive helicopter flight operations on and around the glacier. It included a rushed visit by a large team from CBS News 60 Minutes who were flown and shown all over the place. We last saw the station during 24 hours of day light on 27th August when we calibrated the wind sensors, but to me the daily satellite phone call of the station with new data is a sign of life from an ocean outpost that survived another day in the total darkness of the polar night. It draws energy from two car batteries that run even at the -36 degree Centigrade (-33 F).

AWS

First 100 days of ocean and weather observations from the University of Delaware Ocean Weather Station on Petermann Gletscher, Greenland. Panels show (from bottom to top) time series of 1. battery voltage, 2. ocean (red) and air (black) temperatures, 3. wind speed, 4. wind direction, 5. glacier movement, and 6. atmospheric pressure. Time is given in year-day, Nov.-28 is Day-332. The sun set on Day-290 or Oct.-17.

New data are posted at

http://ows.udel.edu

which over the next few weeks we will develop into a web-site to distribute the daily observations to everyone. I am most thankful to many of scientists, engineers, technicians, sailors, and women in England, Sweden, and the United States of America, but this Thanks-Giving weekend I am grateful to the men and women of a great nation that gave me a place to study, work, and live doing while exploring ocean and now glacier physics as well.

EDIT: I just discovered this 7 minute video on our expedition, credits go to Saskia Madlener at 77th Parallel Productions: