Tag Archives: oceanography

Polar Bears and Guns and Politics

Polar bears are endangered and need protection. They hunt and eat meat to survive. Seals are such meat as are scientists walking and working on the sea ice. I am planing an experiment in polar bear habitat. Do I need a gun to protect myself and my students working with me? About 10 people told me “YES” last week, all with experience working in polar bear habitat. Who am I to say no? Encounters between bears and people happen, but only rarely. None of the 10 people advising me to carry a shotgun or rifle ever discharged their weapon or had a bear encounter.

Polar bear as seen in Kennedy Channel on Aug.-12, 2012. [Photo Credit: Kirk McNeil, Labrador from aboard the Canadian Coast Guard Ship Henry Larsen]

Polar bear as seen in Kennedy Channel on Aug.-12, 2012. [Photo Credit: Kirk McNeil, Labrador from aboard the Canadian Coast Guard Ship Henry Larsen]

In 3 month’s time I hope to do ~20 day trips from Thule Air Base near Pituffik, Greenland to explore the oceanography and acoustics of the local fjord covered by sea ice. The US National Science Foundation supports this work, maintains a dormitory where we sleep, and provides us with two snowmobiles. We will use these motorcycles on skies to reach science stations on the ice covering Wolstenholme Fjord. We will drill 10” holes through 3-5 feet of sea ice, set-up an electric winch connected to a small generator, and probe the ocean’s temperature, salinity, bottom depth, and ice thickness to prepare for a quiet acoustic communication system to move data under water from the outer fjord to the pier at Thule and the internet.

Thule-NSF2017

Leading this science effort, I will have to estimate and manage potential risks which include encounters with polar bears. I will have to decide how much money to allocate to each risk that then may not be available for other activities such as to support students, buy better sensors, or return in the summer. The first and almost always best response is to hire a local hunter who knows the area along with its bears, ice, and weather. There are about 600 people living in Qaanaaq about 100 miles to the north. Most of them are children and grand-children who were forcibly removed from Pituffik in 1952 when more than 13,000 Americans built a large air field during the height of the Cold War. The local llanguage spoken in remote Qaanaaq is the Inuktitut dialect of north-west Greenland, the first foreign language learnt in school is Danish, and English is not widely spoken, however, Qaanaaq has two non-Inuit villagers who originate from Denmark and Japan.

Relations between Qaanaaq and Thule Air Base are complex and sensitive with regard to politics and finances. One of many perspective is that of Kim Petersen who writes in Dissident Voice about “The Struggle against Colonialism and Imperialism in Kalaallit Nunaat.” Kalaallit Nunaat refers to Greenland in the local language. While the forced removal of native populations from Pituffik to Qaanaaq in 1952 and the crash of a nuclear armed B-52 bomber into Wolstenholme Fjord in 1968 are not in dispute, the political arguments presented seem to me rather narrow, one-dimensional, and rooted in a tired ideological Left-Wing mode of conspiracy-thinking. Does this perspective represent the community of Qaanaaq? Perhaps I need to ask someone who may know:

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

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

It is not straight-forward to bring a gun to Greenland as it requires a large amount of paper work. Another layer of regulations relates to bringing a gun to an US military installation. Shooting a polar bear is a burocratic and political nightmare, because strict quotas exist for the “taking” of polar bears. International complications include Canada, because the quotas are assigned to Canadian and Greenlandic hunters from the same bear population. It is a sensitive topic in many dimensions, a riddle for which I have no solution.

How much time do I spent to prepare for an unlikely event such as a fatal polar bear encounter? Could I not argue with ethics that were instilled into me when hiking in the back-country of Denali National Park (no guns there). Park rangers then told me that I enter bear habitat and should do so respectfully with minimal impact. They gave me useful pointers on how to lower contact and I saw no bears hiking for 4 days alone without a gun, but grizzlies eat berries while polar bears do not.

So, should I carry a gun, if I am not ready to kill a bear while working in bear country? I can accept the consequences of injury and death for myself, however, I cannot do so for those who are with me. Perhaps this then is a path to a solution: Discuss this with all who will be with me on the ice.

Why am I a ‘data’ guy?

A journalist asked me an unexpected question today:

It seems like you go out on a lot of ships to remote places. Why is that the kind of science that appealed to you?

As a physical oceanographer I indeed spend a lot of time away from home, about 18 months total the last 20 years or so, but here is how I answered the question quickly without too much reflections:


I always collected my own data starting in 1985 as a German undergraduate in Bangor North Wales. I did code a numerical model on tidal wave breaking for my MS thesis, but it was motivated by the very data I collected while camping next to a small tidal river (and pub) for 4 weeks in Wales.

Study location of the Conway Estuary in North Wales from Muenchow and Garvine (1991).

Study location of the Conway Estuary in North Wales from Muenchow and Garvine (1991).

The why never occurred to me, but I was always following opportunities small and large that got me onto a ship both small and large. Perhaps it is the type of people and their many different backgrounds that I felt close to or whose company was just fun. I could never relate to the more cut and dry personalities that one finds in the academic bubbles of academia.

There is also a thrill of probing the ocean in ways or places that nobody has done before which perhaps explains the remote places. Most people consider this hard-ship to be away from friends, family, and the comforts of home. They go once or twice and then stop early in their careers or as students. To me this hardship is pleasure as it always shatters earlier expectations. The only constant, it feels, is change and new insights, this drives me, perhaps I am addicted to it, perhaps I also push and change myself and the field work gives me this chance or opportunity to “reset” and take a new look at what I thought I knew or I knew I did not understand. Again, this is pleasure and the harder it is, the more pleasure I expect.

This is all the time I have now, short version: It is fun to be in the field and work with great people whose greatness – as with the data – will often become clear only later. I know and embrace this.

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.

New ocean data from floating Petermann Glacier

#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.