Monthly Archives: September 2015

New ocean data from floating Petermann Glacier

Posted on September 25, 2015 by | 8 comments

#UDel Ocean-Weather station #Greenland on #petermann2015 calls home from 800 m under floating glacier with 2 weeks of new hourly data.

University of Delaware Ocean-Weather station on Petermann Glacier with the hot-water drilling team UDel and British Antarctic Survey after deployment Aug.-20, 2015 [Credit: Peter Washam, UDel]

University of Delaware Ocean-Weather station on Petermann Glacier with the hot-water drilling team UDel and British Antarctic Survey after deployment Aug.-20, 2015. Cables from ocean sensors emerge from the ice where the wooden cross is located on the right. [Credit: Peter Washam, UDel]

Map of Greenland's Petermann Gletscher, Fjord, and adjacent Nares Strait. The UDel Ocean-Weather station is the green dot on the floating ice shelf that does not have a red triangle. Blue dots in the ocean are where we collected ocean data from I/B Oden in August 2015. Green dots are ocean moorings which report via Iridium while red triangles are "fancy" GPS locations we instrumented for 12 days to measure vertical tidal elevations of the glacier.

Map of Greenland’s Petermann Gletscher, Fjord, and adjacent Nares Strait. The UDel Ocean-Weather station is the green dot on the floating ice shelf that does not have a red triangle. Blue dots in the ocean are where we collected ocean data from I/B Oden in August 2015. Green dots are ocean moorings which report via Iridium while red triangles are “fancy” GPS locations we instrumented for 12 days to measure vertical tidal elevations of the glacier.

My nerves are shot and I get depressed when the Ocean-Weather station does not call home when she should. We deployed the station last months on the floating section of Petermann Gletscher where she has moved steadily towards the ocean at about three meters per day. We measure this with GPS which is the black dot next to the temperature sensor above the head of the team that drilled the hole. It connected 5 ocean temperature, salinity, and pressure sensors to 800 meter depth below sea level. The data come from this great depth to the surface where it feeds into the weather station that then transmits data via an Iridium antenna to another Iridium antenna that sits atop my house. Let me run out and take a quick photo of it …

Iridium antenna atop my house in Newark, Delaware that receives data calls from Greenland.

Iridium antenna atop my house in Newark, Delaware that receives data calls from Greenland.

My problem with Iridium over the last 6 weeks has been that its (data) connectivity is spotty. For example, I received no data the last 2 weeks. This has been the longest time with no call and no new data. Designing the system, I decided against the more robust “Short-Burst-Data” SBD text messages. Instead I opted for a truly 2-way serial connection which, if a connection is established, allows more control as well as a more complete and gap-free data stream. The drawback of this serial connection via Iridium is lack of connectivity. Sometimes days or weeks go by without a successful connection even though computer codes are written to connect every 8 hours. I can change that by uploading new codes to the two Campbell CT1000 data loggers that control all sensors as well as data collection and communication via Iridium.

Today’s call was the first in two weeks, but it provided a complete data download without ANY gaps in the hourly time series of weather in the atmosphere (wind, temperature, humidity) and weather in the ocean (temperature, salinity, pressure). The ocean data show that about every 2 weeks with the spring-neap cycles, we see very large excursions of colder and fresher water appear at 2 sensors within about 30 meters of the glacier ice. It is too early to speculate on how this may relate to ocean circulation and glacier melting, but the large and frequent up and down do suggest a lot of ocean weather.

I am anxiously awaiting the next data call in about 5 hours to get the 8 hours of data. Wish me luck and a healthy Iridium satellite system where calls are about $0.90/minute. Today’s call took 5 minutes. This is what some of the (uncalibrated) data look like:

Ocean-Weather station data from Aug.-20 through Sept.-25 (today). Ocean temperatures at 5 vertical levels are shown as 5 red curves in 5th panel from top. The black lines in that panel are air temperatures that reached -20 C this week.

Ocean-Weather station data from Aug.-20 through Sept.-25 (today). Ocean temperatures at 5 vertical levels are shown as 5 red curves in 5th panel from top. The black lines in that panel are air temperatures that reached -20 C this week.

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Posted in Arctic Glacier, Greenland, Iridium, Petermann Glacier, Petermann2015

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Ocean Weather Below a Greenland Floating Glacier

Posted on September 17, 2015 by | Leave a comment

Sensing the oceans below ice as thick as the Empire State Building is tall, we are revealing some of the mysteries of ocean melting of one of Greenland’s largest glaciers. The expedition to Petermann Fjord last month made possible the deployment of three ocean sensing stations that all call home daily via Iridium satellite phone to send us new data from 800 meters below sea level. The ice of the glacier at our stations is 100 to 300 meters thick and a whimsical cable with 3 tiny wires connects the instruments under the glacier to a home-made computer that calls home daily with new data. I am still stunned at the many marvels of technology that all came together to make this happen.

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.

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.

Panoramic view of the ocean-weather station on Petermann Gletscher. View is towards the south-east with Washington Land in the background. [Photo credit: Peter Washam].

Panoramic view of the ocean-weather station on Petermann Gletscher. View is towards the south-east with Washington Land in the background. [Photo credit: Peter Washam].

It started with an off-the-shelf automated weather station that David Huntley at the University of Delaware put together for me with the non-standard addition of 5 serial ports that each allow one ocean sensor to be connected by cable to the weather station. It continued with the holes that Paul Anker and Keith Nicholls of the British Antarctic Service drilled through Petermann Gletscher. My PhD student Peter Washam was on the ice helping with the drilling, preparing the ocean sensors, and he is now processing some of the new ocean data.

AWS2015

The map above shows Petermann Gletscher (bottom right), Petermann Fjord, and adjacent Nares Strait. The red lines are bottom depths at 500 and 1000 meters while the thick black line shows the location where the 550-m thick glacier sits on bed rock. All glacier ice seaward of this black line is floating with warm ocean waters below. These waters enter the fjord at he sill at the entrance to Petermann Fjord which is about 450 meters deep. The blue dots are locations where last months we collected detailed profiles of ocean temperature salinity, and oxygen. The warmest water inside the fjord and under the glacier enters near the bottom at this sill. The green dots on the glacier are the 3 drill sites where we put our ocean sensors down while red triangles are “fancy” GPS receivers that we placed for almost 2 weeks on the glacier. The one triangle on land (bottom right) is a permanent GPS station at Kap Schoubye that UNAVCO maintains under the code name SCBY. We will reference our moving glacier GPS station (the glacier moves) to this fixed station on bed rock, but that’s a story for another day.

The ocean data are worked up by a small, but wonder group of men and women of all ages working out of the universities of Gothenburg (Sweden), Oxford (England), and Delaware (USA) as well as BAS (England). It is very much an informal group of people who like each other and met in strange ways over the last year or so with all of us juggling way too many projects for which we all have way too many ideas. Bottom-up collaboration and sharing at its best from the bottom up.

Two quick highlights rushed onto these pages before I have to run off to teach a class on signal processing:

Measurements from the ocean weather station up until 2015-Sept.-11 as a function of time where Day-20 is Aug.-20 and Day-32 is Sept.-1. The station provides battery voltage (bottom panel), air and ocean temperatures, wind speed and direction, ice drift from GPS, and atmospheric pressure (top panel).

Measurements from the ocean weather station up until 2015-Sept.-11 as a function of time where Day-20 is Aug.-20 and Day-32 is Sept.-1. The station provides battery voltage (bottom panel), air and ocean temperatures, wind speed and direction, ice drift from GPS, and atmospheric pressure (top panel).

Ocean temperature (black) and salinity (red) observations from below the ice shelf of Petermann Gletscher at 5 different vertical levels from near the bottom (bottom panel) to the ice-ocean surface (surface panel).

Ocean temperature (black) and salinity (red) observations from below the ice shelf of Petermann Gletscher at 5 different vertical levels from near the bottom (bottom panel) to the ice-ocean surface (surface panel).The bottom of the ice shelf is about 90 meters below sea level.

Note that the scales for temperature and salinity are different at different vertical levels. The warmest water is always found near the bottom while both temperature and salinity under the ice shelf vary by a larger amount that we had initially expected. This means that there are direct and fast connections of the ocean under the glacier with waters inside the fjord and beyond. Notice also that air temperatures are well below freezing (0 degrees Celsius) for 2-3 weeks now while the ocean waters are well above freezing (-1.7 degrees Celsius) everywhere. Hence there is no melting at the surface while there is much melting at the bottom of the glacier. While trivial, this emphasizes the controlling influence that the oceans have on glaciers and ice shelves such as Petermann Gletscher. In the meantime, we got much exciting and fun work ahead of us.

Shout of thanks to NASA (and the US tax-payers) who funded this ocean-weather station at the University of Delaware at about $64,000 for a single year and NSF (and again the US taxpayers) who funded the larger ocean- and land-based experiments within which small part was embedded.

Münchow, A., Padman, L., and Fricker, H.A. (2014). Interannual changes of the floating ice shelf of Petermann Gletscher, North Greenland from 2000 to 2012, Journal of Glaciology, Vol. 60, No. 221, doi: 10.3189/2014JoG13J135

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

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

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Posted in Computing, Greenland, Oceanography, Petermann Glacier, Petermann2015

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Oceanographers in Thule, Greenland

Posted on September 10, 2015 by | 4 comments

Returning from Petermann Fjord and Gletscher, we left the Swedish icebreaker I/B Oden and its fine crew yesterday afternoon. Our military plane to southern Greenland is broken with spare parts needed to be shipped in from Air Force bases in the United States and Germany. Thule Air Force Base (AFB) at Pituffik is the northern-most US military installation that is maintained since the Cold War with lots of help from Danish authorities and workers. Thule AFB is a large airfield and supply center for much of northern Greenland and beyond. Air temperatures are in the 40ties and it feels very warm after sailing south for 3 days to get here.

As last year, the first thing I did after living for 5 weeks in tight quarters on a ship was head out into the wilderness. While almost everyone else was partying ashore after raiding the local supermarket for fresh fruit, vegetables, beer, and wine, Frederik and I headed out the to climb the mountain that I wanted to climb since I first set eyes on it in 2003. We did not set out until well past 6pm local time, but with lots of sunlight even past midnight, we set out. Who knows if and when we may get this opportunity again. There were also some geocaches.

Geocaching map of Thule AFB, North Mountain, and Dundas Mountain. Smiley faces show that I found and opened the hidden treasures.

Geocaching map of Thule AFB, North Mountain, and Dundas Mountain. Smiley faces indicate that I found and opened the hidden treasures.

Frederik is Swedish ecologist whose work around Petermann Fjord was mostly land-based. Leading a group of 3-4 researchers, he was taking an inventory of plant and wild life in a methodical way by setting out a grid 2 meters by 2 meters at random locations. His team then painstakingly counted and recorded every bit of plant, seed, or animal excrement (=shit) that they could find and count. They were living in tents for 5-10 days at a time, returned to the ship via helicopter for a shower, a meal, and to change study area. Within 8 hours his group was usually gone again not to be seen for another 5-10 days.

In contrast to these intense “working hikes,” our leisurely 4 hour stroll was relaxing as he had to record nothing and did not have to lead anyone. Nevertheless, I got blisters on my feet that were well worth this guided nature tour as Frederik patiently answered all my questions on all the trees (1 inch high), all the flowers (1/3 inch), and all the animals that we we saw (falcons, hares, foxes). He also told me that during our 4 hour hike he saw more wild and plant-life than he had seen the entire 4 weeks earlier up north in Hall and Washington Land of Greenland and Ellesmere Island of Canada. There are shades of gray and there are many shades of bare.

On our way out of town we followed the road to get to a bridge that crossed a big stream of run-off from the nearby Greenland ice sheet that was visible in the distance. Quickly, however, we noticed that the dusty roads are not really leading us to where we wanted to go, so we made our own path over the ridge to the north of town called creatively “North Mountain.” From there we hiked down to the beach of an isthmus that connects to the landmark Dundas Mountain with remains of the old village on this spit of sand and gravel. A group of Danes in trucks and on all-terrain vehicles greeted us at the bottom of Dundas Mountains. Frederik later told me that they were mostly trying to get information on women that may have arrived with us, but they also encouraged us to race up the 60 degree slope. The record apparently stands at 6 minutes and 45 seconds, but we were in no mood to race … quite the opposite: We wanted to take in the views and relax amidst stunning natural beauty in the rough:

Once atop I found the geocache I was looking for as well as a trackable treasure. When I recovered this trackable and posted the find online, I got an elated e-mail from Australia where the owner of the treasure lives. The treasure is now with me in Delaware where I will hide for other people to find and move along in a wonderful game of hide and seek and traveling.

Now that I am home again after 6 weeks away without real internet or e-mail access (imagine the horrors), I want to tell some of the many stories that involve a group of people doing science, making discoveries, and share what they find. Most of us are deeply grateful for the privilege to make these discoveries: It is people like you, my dear reader, because the funds for ships and planes and food and fuel and much more comes from organizations like the National Science Foundation, the National Aeronautics and Space Administration, as well as the US Department of Defence, but ultimately the funds all come from tax-paying citizens of a great country.

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