Category Archives: Petermann Glacier

Lab Notes of a Physical Oceanographer

I go to sea to learn about oceans, glaciers, weather, and climate. Despite dramatic photos of exciting field work, those action-packed scenes or serene nature shots of beauty and violence are misleading. Most of my time is spent sitting an a desk in a spacious office with books, papers, telephone, and most important of all, my computers.

Most of my time is spent writing. The writing is varied and ranges from illustrated essays on IcySeas.org to computer code. Add technical writing of research proposals, papers, and reviews for funding agencies and scientific journals. My screen rarely looks like what is shown above with the beautiful LandSat image of 79N Glacier as a screen-saver, it actually looks like this

Picture 2

The blog-writing window is open on the right while a Fortran computer code is in the top left. The code processes temperature, salinity, and pressure data from Petermann Glacier. When the code is run in the bottom-left window, it produces numbers. In this specific case, the numbers are from the only profile of temperature and salinity that exists from Petermann Glacier. Koni Steffen collected the data in 2002. Columns are depths that start at -68 (meters), salinity at 33.774 (no units, think of this as grams per kilogram), temperature at -1.885 (degrees centigrade), and the last column is the density anomaly These numbers are better presented as a graph:

Koni2002raw

Notice that temperature and salinity start only at -68 meters. This is because the ice at this location was about 68-m thick. The Big Ben clock in London is about 96-m high, but this piece if Petermann was chosen because it was less hard to drill through 2/3 of Big Ben’s height when compared to drilling through the glacier ice a mile away where the ice is thicker than the Empire State Building in New York; but I digress.

The profile above reveals a pattern we find almost anywhere in deeper Arctic Waters: Temperature increases with depth. Under the ice at 68-m depth, water is at its freezing point. As you move down the water towards the bottom, salinity increases and so does temperature. It is still cold, about +0.2 degrees Celsius, but this is heat from the North Atlantic Ocean that for perhaps 20-50 years circled all the way around the Arctic Ocean from northern Norway, past Siberia, past Alaska, past Canada to reach this spot of Greenland. While this appears marvelous, and it is, this is NOT what gets a physical oceanographer excited, but this does:

Koni2002Gade

It is the same data, but I did some reading, physics, algebra and code-writing in that order. First, instead of temperature, the blue line shows the difference between temperature T and the temperature Tf above the freezing. The difference T-Tf relates to the amount of heat available to melt the ice somewhere. The black line is the real killer, though. It combines salinity and temperature observations to reveal where the glacier water resides at this location that was melted somewhere else. Without going into the physical details, glacier meltwater is present where the black line touches zero (the so-called Gade-line, so named after a Swedish oceanographer who proposed its use in 1979). This happens at a depth from about 280-m to 500-m depth. This means that the glacier is NOT melting where it is as thin as Big Ben, but instead where it is as thick as the Empire State Building. So this is where we will need to place our instruments.

Proving my initial point, I spent two hours of fun writing this blog. I now will have to focus on more technical writing to pay the many bills of sea-going research. These “lab-notes” also serve as a document to raise $10,845 to install instruments this summer through Petermann Gletscher, have a look and give a little, if you can at

https://experiment.com/projects/ocean-warming-under-a-greenland-glacier

First sensors for future Petermann Gletscher Observatory, Greenland

Two ocean sensors arrived from Germany where I used them last in an experiment off the coast of Greenland last year. I bought them in 2002 and they have been in Arctic waters most of the time where they measure ocean temperature and conductivity very accurately a few times every second. Conductivity of seawater is what oceanographers measure when they want to talk about salinity and Arctic oceanographers must know salinity if they want to talk about ocean density. Water from cold melting ice and glaciers is less dense (because it is fresh) than the warm and salty water from the Atlantic Ocean that does the melting. You need heat to melt ice, but the heat that melts Greenland from below by the ocean comes from the Atlantic. The heat is at depth 200-400 meters deep, because of salt in the water that makes it dense and sink.

Oceanography and physics are fun, but here are the photos of what I work with over the weekend at home … maybe in my garden, too, to practice for the Arctic deployment, you may even watch me do it on the web-cam in my garden pointing towards the heated bird-bath. Geeks at play, science is fun:

Two SBE37sm with one set of 12 lithium batteries.

Two SBE37sm with one set of 12 lithium batteries.

The housing of these two instruments are rated for 7,000-m depth, I will have to install the lithium batteries ($4.80 for a single AA battery); each instrument needs 12 of those. Since 2003 we deployed a number of these in the Arctic where they collected data for over 3 years every 15 minutes. One of my students, Berit Rabe now works in Scotland and her dissertation and peer-reviewed publication was based on data from a single 2003-06 deployment of about 20 such instruments.

SBE37sm connect via RS-232 cable to the serial port of an old Dell computer.

SBE37sm connect via RS-232 cable to the serial port of an old Dell computer.

The instruments connect via a serial cable to the computers. In the past I had problems with instruments bought 12 years ago, because computers develop faster than oceanographic instrumentation. So, new is not always better, so I bought an old Dell Windows XP machine on e-Bay for $200 (actually I bought 2) to make sure that my sensors match software, CPU, and operating systems of the time that the instruments were bought. In order to “talk” to the sensors, I will need to put the lithium batteries into them. I am very much looking forward to do this over the weekend.

To be continued …

Note: This is a lab-note from my crowd-funding experiment at https://experiment.com/projects/ocean-warming-under-a-greenland-glacier.

Greenland Glacier Ocean Warming

The Swedish icebreaker Oden will visit Petermann Fjord in northern Greenland in 6 months time. The US National Science Foundation (NSF) funded a large geophysical and geological experiment after excruciating peer-review over a 4-year period. The experiment shall reveal climate histories from sediment cores, geomagnetics, and both bottom and sub-bottom sonar profiling. Besides this main mission Oden also supports several smaller auxiliary projects some of which are funded by NSF while others are not. It will be a fine collaboration between Swedish and American scientists working together in perhaps one of the most difficult to reach and beautiful places on earth.

Seaward front of Petermann Glacier Aug.-11, 2012. View is from a small side-glacier towards the south-east across Petermann Fjord with Petermann Gletscher to the left (east). [Photo Credit: Erin Clarke, Canadian Coast Guard Ship Henry Larsen]

Seaward front of Petermann Glacier Aug.-11, 2012. View is from a small side-glacier towards the south-east across Petermann Fjord with Petermann Gletscher to the left (east). [Photo Credit: Erin Clarke, Canadian Coast Guard Ship Henry Larsen]

I will aboard the ship to deploy sensors some of which exist and are funded while others are neither. Let me outline first the funded part and then part where you the reader and I can perhaps join forces. First, we will test first elements of an underwater acoustic communication system. Think cell-phones, except the phone towers are under water where they are called modes. The modems talk to each other by sending sound back and forth the same way that whales do talk to each other.

Here is a narwhals sound

that you can use as a ringtone, credit goes to Voices of the Sea web-site at Scripps Institution of Oceanography. These whales visit Petermann Fjord in summer and we saw many of them frolicking in August of 2012 when I visited the area with the Canadian Coast Guard whom I credit for these photos:

Our man-made sound is very quiet, but because it is quiet, it only moves 3-10 km through the water. To increase our range, we plan to install several quiet sound sources that whisper from one water-phone (=hydrophone) to the next. The goal is to get data from ocean sensors moved along this whispering system of underwater “cell phones” to reach a listening station that we plan to install at the edge of Petermann Gletscher’s floating ice shelf. The ice is 200 meters or 600 feet thick and it is not trivial to drill through that much ice, but it can be done, and the British Antarctic Survey is aboard with a team of experts to do so to get sediment cores from the bottom below the ice:

Makinson1993-Fig04

Today I ordered a first cable that will connect the underwater modem hanging under the 200-m thick ice to the surface where a fancy computer connects it to the internet via to a satellite phone. All data calls that the underwater listening station receives will move up the cable to the glacier surface and on to us all via the internet. This challenging engineering project is funded, but I like to use the same hole, computer, and satellite link to get additional ocean and air data.

Additional stations will be drilled through the ice-shelf farther inland to reach the ocean also. Here we also need cables and instruments that tells us how the glacier is melted by the ocean at different location along its 50 km long floating ice shelf. The incremental costs are small relative to the cost of getting a ship and helicopters there, but NSF cannot easily fund small projects rapidly. It takes a long time to pass scientific peer review. This is where you, my dear reader come in: I need your help to raise $10,000 to add science and observations to an engineering feasibility study that is the underwater whispering sound system.

The motivation and details are described with videos, pictures, laboratory notes, plots, ideas, as well as some short, quirky, yet technically correct descriptions at the crowd-funding site

https://experiment.com/projects/ocean-warming-under-a-greenland-glacier.

I created and launched it today, it will be up for 30 more days. If you can and if you like the science, work, and fun that I describe on these pages, please consider making a small donation. You have the power to make this happen and I will share all data both from below and above the ocean and glacier surface with you.

As a physicist, gardener, teacher, writer, traveler, ping-pong player, and geocacher I am naturally curious about both our natural and social world. I love experiments and to me the crowd-funding at Experiment.com is a most enjoying experiment to connect to people in a new way. Full disclosure, however, this company takes 8% of all funds generated to supports its wonderful software and staff. Perhaps you like to join this experiment by spreading the word and, if you can afford it, help pay for some of the technology needed to bring Greenland and its mysteries to everyone who wants to connect to it.

Glaciers, Geocaching, and Greenland Goals

I thought it silly when my wife suggested to go geocaching with her. She told me it was to hunt for treasures and as a professor of physical ocean science and engineering this was not for me. But my wife is persistent, I am curious, and when she explained that a GPS, hiking, and computer mapping was involved, I gave it a try and have been hooked ever since. My first geocaching hiking trip took place on Anacortes Island, Washington in 2013 where our youngest son then lived. Here we are walking past rock carved 10,000 years ago by a tiny glacier at N 48° 29.498 W 122° 41.799 N that discharged ice into Puget Sound:

Glacier carved outcrop in Washington Park, Anacortes Island, WA.

Glacier carved outcrop in Washington Park, Anacortes Island, WA.

Since this first geocaching trip, I have found more than 200 geocaches in places small and remote and places large and urban. The treasure is in the walking and trying to find a path towards a destination, but the destination is secondary as many discoveries are made along the way.

This often happens in science also. One needs to know a destination, have a goal, formulate a hypothesis, but much science, learning, and discovering happens along the path towards that goal. With a GPS the destination is easy, it is a fixed point on earth, but it is harder in science. It can be useful to roam widely, but a set of intermediate goals can help to stay focused. For example, I want to understand how Greenland will change as we warm the earth. That’s a big question with impacts on floods in Europe, storms in the Americas, and rising sea level everywhere. This is a 100-year problem that many people work on; so my personal goal is to focus on how the oceans melt glaciers from below. This is a 10-year problem. It is a step towards the larger goal, but 10 years is still long even though I work with people in Germany, Canada, Denmark, England, Sweden, and Norway:

View to the south on the climb down from Tromsdalstinen.

View to the south on the decent from Tromsdalstinen on a geocaching trip in 2014 out of Tromso, Norway.

The photo above was made during one of my geocaching trip in northern Norway. Three physical oceanographers had gotten off the ship after they deployed ocean current measuring devices off eastern Greenland near a larger ice sheet. The experiment was designed to measure the ocean heat and its movement towards two large outlet glaciers. One has a wide and stable floating ice shelf, Nioghalvfjerdsfjorden (79N Glacier) while Zachariae Isstrom a few miles south lost its wide, long, and apparently unstable ice shelf that still shows in this 2002 image:

North-east Greenland: 79N Glacier and Zachariae Isstrom in 2002.

North-East Greenland in 2002 when both 79N Glacier (near 79 30′) and Zachariae Isstrom (near 79 00′) had extensive ice shelves (black areas are open ocean).

It puzzles me how two adjacent glaciers can and do behave so differently. If we understand how Greenland is melting, then we should explain the difference convincingly, but I am still looking for people who can. Lots of theories, lots of ideas, and lots of modeling, but there are not many observations to make the skimpy and often contradictory evidence convincing. And this finally leads me to my last point and the goal that I set for myself for the next 5-10 years:

I like to measure the ocean, the ice, and the air above and below floating glaciers via a small network of sensors. Now that two large ice islands spawned at Petermann Gletscher in 2010 and 2012, I believe that the remaining ice shelf will stay largely put for the next few years, that is, move at 1 km per year towards Nares Strait:

Petermann Gletscher through calving events. White lines show ICESat tracks; red (ambient ice shelf) and blue (central channel) show repeat-track airborne surveys.

Petermann Gletscher through calving events. White lines show ICESat tracks; red (ambient ice shelf) and blue (central channel) show repeat-track airborne surveys.

The hardest part in reaching this goal is to get measurements from under the 200-600 meter thick ice. This requires holes drilled through the glacier, it requires ocean sensors to be lowered into the water below the glacier, and it requires connections to relay data back to the surface at all hours for many year. I  perhaps have a first chance towards this goal when the Swedish icebreaker Oden will work for a month in Petermann Fjord this year. People from the British Antarctic Survey will be aboard and they plan to drill holes for other scientific purposes. When they are done, the holes freeze over, unless someone (me, me, me, please, pretty, pretty please) has instruments to put in there. I just word that I will be aboard the ship as well and I am feverishly working towards this goal with much help from others. More on this in later posts. All science is a group effort.

I close with a photo to show how the ice-covered ocean of Petermann Gletscher looks during the polar day. Would it not be great to know the temperature of the water below and the air above this more than 200 meter thick glacier ice at all times posted for everyone to use with an internet connection?

March-24, 2010 view of Petermann Glacier from NASA's DC-8 aircraft. Photo credit goes to Michael Studinger of NASA's IceBridge program.

March-24, 2010 view of Petermann Glacier from NASA’s DC-8 aircraft. Photo credit goes to Michael Studinger of NASA’s IceBridge program.

A Short Summary of Nares Strait Physics

The Arctic Ocean is a puddle of water covered by ice that melts, moves, and freezes. Grand and majestic rivers of Siberia and America discharge into the puddle and make it fresher than Atlantic Ocean waters. The fate of the Arctic freshwater helps decide if Europe and the US become warmer or colder, experience more or less storms, droughts, or floods, and if global sea level will rise or fall. In a nutshell: the fate of Arctic freshwater determines climate.

Arctic Ocean with Nares Strait study area (red box) with tide gauge locations as blue symbols and section of moored array as red symbol. Contours are bottom topography that emphasize ocean basins and continental shelf areas.

Arctic Ocean with Nares Strait study area (red box) with tide gauge locations as blue symbols and section of moored array as red symbol. Contours are bottom topography that emphasize ocean basins and continental shelf areas.

Nares Strait connects the Arctic and Atlantic Oceans to the west of Greenland. It is narrower than Fram Strait, but it transports as much fresh ocean water as does its wider sister facing Europe. Few people know this, including climate scientists who often model it with a bathymetry that is 10,000 years out of date from a time when Nares Strait did not yet exist. This is why the US National Science Foundation funded a group of oceanographers to use icebreakers, sensors, computers, and innovative engineering to collect and analyze data on the ice, the water, and the atmosphere.

Acoustic Doppler Current Profiler mooring deployment in Nares Strait from aboard the CCGS Henry Larsen in 2009.

Acoustic Doppler Current Profiler mooring deployment in Nares Strait from aboard the CCGS Henry Larsen in 2009.

Within days of the start of the grant I had to appear before the US Congress to answer questions on Petermann Glacier that discharges into Nares Strait. In 2010 a large 4-times Manhattan-sized ice islands broke off and people wanted to know if global warming was to blame. I was asked how ocean temperatures and currents relate to this and other events and what may happen next. My few data points were the only existing data for this remote region, but I had not yet had the time to analyze and publish much. Two years later another large 2-Manhattan sized ice island formed from the same glacier, but this time we were better prepared and people world-wide went directly to our data, thoughts, and stories when this blog was sourced in news papers in France, Germany, and China. Al Jezeraa, BBC, and PBS reported on it, too, giving me chance to connect via TV, radio, and pod-casting to a larger public.

Petermann Gletscher in 2003, 2010, and 2012 from MODIS Terra in rotated co-ordinate system with repeat NASA aircraft overflight tracks flown in 2002, 2003, 2007, and 2010. Thick black line across the glacier near y = -20 km is the grounding line location from Rignot and Steffen (2008).

Petermann Gletscher in 2003, 2010, and 2012 from MODIS Terra in rotated co-ordinate system with repeat NASA aircraft overflight tracks flown in 2002, 2003, 2007, and 2010. Thick black line across the glacier near y = -20 km is the grounding line location from Rignot and Steffen (2008).

While it was exciting and fun to share Nares Strait and Petermann Gletscher physics with a global audience, it is not what we had planned to do. Our goal was to put real numbers to how much water, ice, and freshwater was moving from the Arctic to the Atlantic via Nares Strait. So the next 3 years we labored through our extensive records to first describe and then to understand what was happening in Nares Strait. We found that ocean currents move water always to the south no matter if ice covers Nares Strait or not, no matter if the ice is moving or not, no matter which way the wind is blowing. The physical cause for this southward flow is that the sea level is always a few inches higher in the Arctic Ocean than it is in Baffin Bay and the Atlantic Ocean to the south.

Linear regression of volume flux  through Nares Strait from current meters with along-strait sea level difference from tide gauges (unpublished).

Linear regression of volume flux through Nares Strait from current meters with along-strait sea level difference from tide gauges. (unpublished).

We know, because we measured this with tide gauges that we placed in protected coastal bays. We recovered 3 sensors; most rewarding was the recovery of one sensor that we had failed to reach in 2005, 2006, 2007, and 2009, but in 2012 we finally got the instrument and 9-years of very good data. Batteries and computers inside were still running and recording. I have never seen as clean and as long a time series.

Results from a 2003-12 tide record shows as power spectra with named tidal constituents at diurnal (~24 hours) and semi-diurnal (~12 hours) periods. The red line is a modeled red noise spectra (unpublished).

Results from a 2003-12 tide record shown as a power spectra with named tidal constituents at diurnal (~24 hours) and semi-diurnal (~12 hours) periods. Data are shown as the relative amplitudes of oscillations at frequencies in cycles per day or cpd. The red line is a modeled red noise spectra (unpublished).

From satellite data that we analyzed as part of this grant, we know when the ice moves and when it stops moving. The freeze-up of Nares Strait comes in one of three forms: 1. Ice stops moving in winter, because an ice barrier (ice arch or ice bridge) forms in the south that blocks all southward motion of ice; 2. only new and young ice moves southward, because an ice barrier forms in the north that blocks all entry of Arctic ice into Nares Strait; and 3. Arctic ice moves freely through Nares Strait, because no ice barriers are present. Our 2003-12 study period covers years for each of these different ice regimes. And each of these regimes leads to very different ocean (and ice) flux as a result of very different ocean physics.

Data alone cannot make definite statements on what will happen next with our climate, but we know much new physics. The physics suggest certain balances of forces and energy for which we have mathematical equations, but these equations must be solved on computers that can only approximate the true physics and mathematics. These computer models are our only way to make predictions ito the future. The data we here collected and our analyses provide useful checks on existing models and will guide improved models.

June-10, 2012 MODIS-Terra image showing location of moored array that was deployed in Aug. 2009 to be recovered in Aug. 2012.

June-10, 2012 MODIS-Terra image showing location of moored array that was deployed in Aug. 2009.

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

Münchow, A., Falkner, K., Melling, H., Rabe, B., & Johnson, H. (2011). Ocean Warming of Nares Strait Bottom Waters off Northwest Greenland, 2003–2009 Oceanography, 24 (3), 114-123 DOI: 10.5670/oceanog.2011.62

Münchow, A., Padman, L., & Fricker, H. (2014). Interannual changes of the floating ice shelf of Petermann Gletscher, North Greenland, from 2000 to 2012 Journal of Glaciology, 60 (221), 489-499 DOI: 10.3189/2014JoG13J135

Münchow, A., Falkner, K., & Melling, H. (2014). Baffin Island and West Greenland Current Systems in northern Baffin Bay Progress in Oceanography DOI: 10.1016/j.pocean.2014.04.001

Rabe, B., Johnson, H., Münchow, A., & Melling, H. (2012). Geostrophic ocean currents and freshwater fluxes across the Canadian polar shelf via Nares Strait Journal of Marine Research, 70 (4), 603-640 DOI: 10.1357/002224012805262725