Author Archives: Andreas Muenchow

Sea Ice, Oceanography, and Nature’s Way to Paint

I am going to sea next week boarding the R/V Sikuliaq in Nome, Alaska to sail for 3 days north into the Arctic Ocean. When we arrive in our study area after all this traveling, then we have perhaps 18 days to deploy 20 ocean moorings. I worry that storms and ice will make our lives at sea miserable. So what does a good data scientist do to prepare him or herself? S/he dives into data:

Map northern Chukchi Sea with mooring locations (red and blue symbols), contours of bottom topography, and radar backscatter from space.

Map northern Chukchi Sea with mooring locations (red and blue symbols), contours of bottom topography, and radar backscatter from space. Slightly darker shades especially in the bottom segment are interpreted as sea ice. The offset in grey scale between top and bottom is caused by me using different numbers for two different data segments to bring the data into a range that varies between 0 and 1.

The image above is my first attempt to determine, if our planned mooring deployment locations are free of sea ice or not. The darker tones of gray are sea ice with the white spots probably thicker or piled-up ridges of rougher sea ice. The speckled gray surface to the north is probably caused by surface waves and other “noise” that are pretty random. There is a data point ever 40 meters in this image. It also helps to compare these very high-resolution ice data with products that the US National Ice Center (NIC) and the National Weather Service provide:

Ice Chart of the Alaska office of the National Weather Service (link)

Ice Chart of the Alaska office of the National Weather Service

The above is a wonderful map for general orientation, but it is not good or detailed enough to navigate a ship through the ice. The two maps agree, however, my patch of ice to the south of the moorings are represented as the orange/green patch on the top right (north-east). The orange means that 70-80% of the area is covered by ice and this ice is thicker than 1.2 meters and thus too thick for our ship to break through, but there are always pathways through ice and those can be found with the 40-m resolution maps.

In summary, on Sept.-29, 2016 all our moorings are in open water, but this can change, if the wind moves this math northward. So we are also watching the winds and here I like the analyses of Government Canada

Surface weather analysis from Government Canada for Oct.-2, 2016.

Surface weather analysis from Government Canada for Oct.-2, 2016. The map of surface pressure is centered on the north pole with Alaska at the bottom, Europe on the top, Greenland on the right, and Siberia on the left.

It shows a very low pressure center over Siberia to the south-west and a high pressure center over Arctic Canada to our north-east. This implies a strong wind to the north in our study area. So the ice edge will move north into our study area. If the High moves westward, we would be golden, but the general circulation at these latitudes are from west to east, that is, the Low over Siberia will win and move eastward strengthening the northward flow. That’s the bad news for us, but we still have almost 2 weeks before we should be in the area to start placing our fancy ocean moorings carefully into the water below the ice.

While this “operational” stuff motivated me to dive into the satellite radar data that can “see” through clouds and fog, I am most excited about the discovery that the radar data from the European Space Agency are easy to use with a little clever ingenuity and a powerful laptop (2.5 MHz Mac PowerBook). For example, this hidden gems appeared in the Chukchi Sea a few days earlier:

Close-up of the ice edge in the northern Chukchi Sea on Sept.-23, 2016. The mushroom cloud traced by sea ice and associated eddies are about 10-20 km across.

Close-up of the ice edge in the northern Chukchi Sea on Sept.-23, 2016. The mushroom cloud traced by sea ice and associated eddies are about 10-20 km across.

It is a piece of art, nature’s way to paint the surface of the earth only to destroy this painting the next minute or hour or day to make it all anew. It reminds me of the sand-paintings of some Native American tribes in the South-West of the USA that are washed away the moment they are finished. Here the art is in the painting, just as the pudding is in the eating, and the science is the thinking.

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.

Remote Air Strips in North Greenland

Where to land a plane in North Greenland? This remote wilderness has the last floating ice shelves in the northern hemisphere such as Petermann Gletscher. Two weeks ago Dr. Keith Nicholls of the British Antarctic Service (BAS) and I visited this glacier to fix both ice penetrating radars and ocean moorings that we had deployed in 2015 after drilling through more than 100 meters of glacier ice. The BAS radars measure how the ice thins and thickens during the year while my moorings measure ocean properties that may cause some of the melting. Keith and I are thinking how we can design an experiment that will reveal the physics of ocean-glacier interactions by applying what we have learnt the last 12 months. First, however, we need to figure out where to land a plane to build a base camp and fuel station in the wilderness.

I searched scientific, military, and industry sources to find places where planes have landed near Petermann Gletscher. The first landing, it seems, was a crash landing of an US B-29 bomber on 21 February 1947 at the so-called Kee Bird site. All 11 crew survived, the plane is still there even though it burnt after a 1994/95 restoration effort that got to the site in a 1962 Caribou plane landing on soft ground with a bulldozer aboard that is still there also. A Kee Bird forum contains 2014 photos and, most importantly for my purpose, a map.

Location of Kee Bird and other landing sites in North Greenland near Petermann Gletscher. [From Forum]

Location of Kee Bird and other landing sites in North Greenland near Petermann Gletscher. [From Michael Hjorth]

Michael Hjorth posted the map after visiting the region as the Head of Operation of Avannaa Resources. This small mineral exploration company was searching for zinc deposits and was working out of a camp a few miles to the north of the Kee Bird site and a few miles to the west of Petermann Gletscher. The Avannaa Camp was on the north-western side of an unnamed snaking lake in a valley to the south of Cecil Gletscher, e.g.,

Names of glaciers, capes, islands in Petermann Region over MODIS of Aug.-21, 2012.

Names of glaciers, capes, islands in Petermann Region over MODIS of Aug.-21, 2012.

Here are videos that show Twin Otter, helicopter, and camp operations all at the Avannaa site in 2013 and 2014:


The Avannaa camp of 2013 and 2014 was supplied from a more southern base camp at Cass Fjord that Avannaa Logistics and/or another mineral company, Ironbark.gl apparently reached via a chartered ship.

Cass Fjord Base Camp on southern Washington Land and Kane Basin. Credit: IronBark Inc.

Cass Fjord Base Camp on southern Washington Land and Kane Basin. Credit: IronBark Inc.

A summary of all 2013-14 Washington Land activities both at the Avannaa Camp next to Petermann Gletscher and the Cass Fjord Base Camp adjacent to Kane Basin is contained within this longer video of Michael Hjorth

The mining explorations are based on geological maps that Dr. Peter Dawes of the Geological Survey of Denmark and Greenland provided about 10-20 years ago. These publications contain excellent maps and local descriptions both of the geology and geography of the region as well as logistics. The perhaps most comprehensive of these is

http://www.geus.dk/publications/maps/map1_p01-48.pdf

from which I extract this map that shows both the Cass Fjord and Hiawatha Camps:

Dawes (2004): "Simplified geological map of the Nares Strait region ..." from Thule Air Force Base in the south to the Arctic Ocean in the north with Petermann Gletscher in the center of the top half.

Dawes (2004): “Simplified geological map of the Nares Strait region …” from Thule Air Force Base in the south to the Arctic Ocean in the north with Petermann Gletscher in the center of the top half.

while

http://www.geus.dk/publications/review-greenland-99/gsb186p35-41.pdf

has this photo on how one of these landing strips looks like on a raised beach

dawes2000-fig3

If we do plan future activities at Petermann Gletscher and/or Washington Land and/or areas to the north, then I feel that the Avannaa site may serve as a good semi-permanent base of operation for several years. It is here that Ken Borek Twin Otter landed several times. It is reachable with single-engine AS-350 helicopters that could be stationed there during the summer with a fuel depot to support field work on the ice shelf of Petermann Gletscher and the land that surrounds it. The established Cass Fjord Base Camp to the south would serve as the staging area for this Petermann Camp which has both a short landing strip suitable for Twin Otter and potential access from the ocean via a ship. Access by sea may vary from year to year, though, because navigation depends on the time that a regular ice arch between Ellesmere Island and Greenland near 79 N latitude breaks apart. There are years such as 2015, that sea ice denies access to Kane Basin to all ships except exceptionally strong icebreakers such as the Swedish I/B Oden or the Canadian CCGS Henry Larsen. In lighter ice years such as 2009, 2010, and 2012 access with regular or ice-strengthened ships is possible as demonstrated by the Arctic Sunrise and Danish Naval Patrol boats. International collaboration is key to leverage multiple activities and expensive logistics by land, air, or sea in this remote area of Greenland.

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.

Oceanography and Price of Milk at Thule Air Force Base, Greenland

Looking ahead across Greenland’s ice sheet and glaciers and sea ice, I fell in love with Thule Air Force Base when I was stranded there last year. The people I met on base during these 2 days both military and civilian, both American and Danish, were incredible in how they shared their time, their houses, their huts, their containers, their beaches, their hills, and most of all their pride in working together on something special in a hostile, isolated, and beautiful place that is Thule and adjacent Dundas, Greenland. It is stunning to me, however, that this prime location next to a large airfield, next to a deep water port, next to tidewater glaciers, and next to the open, albeit ice-covered ocean has not been used much for field work in oceanography on ice-ocean-glacier interactions. This needs change.

The two days last year in Thule allowed me to walk around and explore for the first and only time in the 12 years that I passed through Thule to board or leave icebreakers working far to the north in Nares Strait and at Petermann Gletscher. Thule is the northern-most deep water port in the world and I have written about some of its Cold War histories, its long, wood-decked pier, and its hikes. My interest in Thule and its pier emerged when the National Science Foundation funded an experimental engineering program on how to send e-mails underwater from one ocean sensor to another much like the way we all do it through the air with our smart cell phones. We want to test this system under the ice and there is plenty of ice around Thule for most of the year.

Thule-NSF2017

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

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

While all this sounds like fun, how does one get stuff like oneself or sensors, or rope, or an entire container of gear to Thule. This turns out to be very tricky as there are no roads to get there, the port is ice-free only from June through October, and the ~600 people living here and another 600 living 60 miles over a mountain and several glaciers to the north do not exactly support a competitive market of air carriers. There is a reason that a gallon of milk should cost $80 were it not subsidized by the US Department of Defence. Actual shipping costs of such items are $10 per pound (452 grams) by air and a gallon of milk weights about 8 pounds. So, if I have 1000 pounds of gear, say, I’d have to pay $10,000 just get it to Thule. For context, I am about to ship 15,000 pounds of oceanographic gear to Seattle for an experiment in the Arctic Ocean later this fall. So, air shipment is not really practical for larger experiments, however, this is

which is Operation “Pacer Goose” run by the US Navy SeaLift Command. Once every year in early July it provides the bulk of supplies and fuel to remote Thule Air Force Base. Think container-sized stuff. It is also the reason, that my experiment in the coastal waters of Wolstenholme Fjord should not be in the way of this annual event that uses the pier. Here is the M/V Ocean Giant as seen from the pier at Thule:

100_0287

My only problem now is that to use this container ship, the earliest possible date to use the container I may want to ship is in the fall of 2017. So, do I want to do oceanography while walking and driving on water frozen solid by sea ice in March and April … or is there a way to deploy my oceanographic sensors via a small boat in the open waters in the fall? New ideas and questions to ponder. This, however, is always fun, too many ideas, each new problem is also an opportunity to do things differently, perhaps. And a good, solid, and comprehensive oceanographic study of the waters off Thule is, I feel, overdue. [I also need to talk to my Danish friends and colleagues about this, more ideas yet.]