Tag Archives: Arctic Ocean

Only in Thule Greenland

… do you find a machinist working metal to take photos while I do oceanography the old-fashioned way by pulling up 100 meters of kevlar line to recover an ocean probe.

Wolstenholme Fjord March-26, 2017. [Photo by Mogens Werth Christensen]

The data were subsequently used by ocean acousticians to test speed of sound propagation as part of an NSF project on testing an underwater communication system to move data from A to B via C or D. The automated weather station reports ocean temperature and saltiness as well at

http://ows.udel.edu/ice

Web-site is low-bandwidth to be used operationally by Air Force personnel in Greenland and local communities where internet access and speeds are severely limited.

Greenland Oceanography by Sled and Snowmobile

Wind chill matters in Greenland because one must see and breath. This implies exposed skin that will hurt and sting at first. Ignoring this sting for a few minutes, I notice that the pain goes away, because the flesh has frozen which kills nerves and skin tissue. The problem becomes worse as one drives by snowmobile to work on the sea ice which I do these days almost every day.

Navigating on the sea ice by identifying ice bergs with LandSat imagery. The imagery also shows polynyas and thin ice in the area. [Photo Credit: Sonny Jacobsen]

Mar.-22, 2017 LandSat image of study area with Thule Air Base near bottom right, Saunders Island in the center. Large red dots are stations A, B, and C with Camp-B containing weather station, shelter, and first ocean mooring. My PhD student Pat Ryan prepared this at the University of Delaware.

My companion on the ice is Sonny Jacobsen who knows and reads the land, ice, and everything living on and below it. He teaches me how to drive the snowmobile, how to watch for tracks in the snow, how to pack a sled, and demonstrates ingenuity to apply tools and materials on-hand to fix a problem good enough to get home and devise a new and better way to get a challenging task done. Here he is designing and rigging what is to become our “Research Sled” R/S Peter Freuchen, but I am a little ahead of my story:

Sonny Jacobsen on Mar.-27, 2017 on Thule Air Base building a self-contained sled for ocean profiling.

First we set up a shelter in the center of what will hopefully soon become an array of ocean sensors and acoustic modems to move data wirelessly through the water from point A in the north-west via point B to point C. Point C will become the pier at Thule Air Base while the tent is at B that I call Camp-B:

Ice Fishing shelter to the north-east of Saunders Island seen to the left in the background.

Next, we set up an automated weather station (AWS) next to this site, because winds and temperatures on land next to hills, glaciers, and ice sheets are not always the same 10 or 20 km offshore in the fjord. It is a risk-mitigating safety factor to know the weather in the study area BEFORE driving there for 30-60 minutes to spend the day out on the ice. It does not hurt, that this AWS is also collecting most useful scientific data, but again, I am slightly ahead of my story:

Weather station with shelter at Camp-B with the northern shores of Wolstenholme Fjord in the background. Iridium antenna appears just above the iceberg on the sidebar of the station. Winds are measured at 3.2 m above the ground.

With shelter and weather station established and working well, we decided to drill a 10” hole through 0.6 m thin ice to deploy a string of ocean instruments from just below the ice bottom to the sea floor 110 m below. Preparing for this all friday (Mar.-24), we deploy 22 sensors on a kevlar line of which 20 record internally and must be recovered while 2 connect via cables to the weather station to report ocean temperature and salinity along with winds and air temperatures. It feels a little like building with pieces of Lego as I did as a kid. Engineers and scientists, perhaps, are trained early in this sort of thing.

Weather station with ocean mooring (bottom right) attached with eastern Saunders Island in the background on Sunday Mar.-26, 2017.

Sadly, only the ocean sensor at the surface works while the one at the bottom does not talk to me. I can only suspect that I bend a pin on the connector trying to connect very stiff rubber sealing copper pins from the cable with terminations equally stiff in the cold, however, there are other ways to get at the bottom properties albeit with a lot more effort … which brings me to R/S Peter Freuchen shown here during its maiden voyage yesterday:

R/S Peter Freuchen in front of 10” hole (bottom right) for deployment of a profiling ocean sensor. The long pipes looking like an A-frame on a ship become a tripod centered over the hole with the electrical winch to drive rope and with sensors (not shown) over a block into the ocean. This was yesterday Mar.-28, 2017 on the way from Camp-B back to Thule Air Base.

The trial of this research sled was successful, however, as all good trials, it revealed several weaknesses and unanticipated problems that all have solutions that we will make today and tomorrow. The design has to be simple to be workable in -25 C with some wind and we will strip away layers of complexities that are “nice to have” but not essential such as a line counter and the speed at which the line goes into the water. There can not be too many cables or lines or attachments, because any exposure to the elements becomes hard labor. This becomes challenging with any gear leaving the ocean (rope, sensors) and splattering water on other components. Recall that ocean water is VERY hot at -1.7 C relative to -25 C air temperatures. This means that ANYTHING from the ocean will freezes instantly when in contact with air. Efficiency and economy matter … as does body heat to keep critical sensors and batteries warm.

A big Thank-You to Operation IceBridge’s John Woods for something related to this post that I wish not to advertise 😉

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.

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.

Sea ice and 2016 Arctic field work

The sea ice in the Arctic Ocean is quickly disappearing from coastal areas as we are entering the summer melt season. This year I follow this seasonal event with nervous anticipation, because in October and November we will be out at sea working north of northern Alaska. We plan to deploy a large number of ocean sensors to investigate how sound propagates from the deep Arctic Ocean on to the shallow Chukchi Sea. This figure shows our study area with the ice cover as it was reported yesterday from space:

Ice concentration for June 14, 2016 from SSM/I imagery. Insert show study area to the north of Alaska and planned mooring locations (red box).

Ice concentration for June 14, 2016 from SSM/I imagery. Insert show study area to the north of Alaska and planned mooring locations (red box).

Zooming in a little further, I show the coast of Alaska along with 100 and 1000 meter contour of bottom depth over a color map of ice concentrations:

Ice concentrations from SSM/I to the north of norther Alaska with planned mooring locations across the sloping bottom. The 100 and 1000 meter contours are shown in gray with blue and red symbols representing locations of ocean and acoustic sensors, respectively.

Ice concentrations from SSM/I to the north of norther Alaska with planned mooring locations across the sloping bottom. The 100 and 1000 meter contours are shown in gray with blue and red symbols representing locations of ocean and acoustic sensors, respectively.

My responsibilities in this US Navy-funded project are the seven densely packed blue triangles. They indicate locations where I hope to measure continuously for a year ocean temperature, salinity, and pressure from which to construct sections of speed of sound and how it varies in time and space. I will also measure ice draft as well ice and ocean currents from which to estimate the roughness of the sea ice over time. Sea ice and ocean properties both impact sound propagation from deep to shallow water and vice versa.

A first question: What will the ice be like when we get there? This is the question that has the 40 or so people all working on this project anxiously preparing for the worst, but how can we expect what challenges are to come our way?

Doing my homework, I downloaded from the National Snow and Ice Data Center all gridded maps of ice concentrations that microwave satellites measured almost daily since 1978. Then I crunch the numbers on my laptop with a set of kitchen-sink Unix tools and code snippets such as

set ftp = 'ftp://sidads.colorado.edu'
set dir = 'pub/DATASETS/nsidc0081_nrt_nasateam_seaice/north'
...
wget -r -nd -l1 --no-check-certificate $ftp/$dir/$year/$file

along with fancy and free Fortran and General Mapping Tools to make the maps shown above. With these tools and data I can then calculate how much sea ice covers any area at any time. The result for custom-made mooring area at almost daily resolution gives a quick visual that I use to prepare for our fall 2016 expedition. The dotted lines in the top panel indicate the dates we are in the area.

Time series of daily ice concentration in the study area for different decades from January-1 through Dec.-31 for each year from 1980 through 2015. Panels are sorted by decade. The red curve is for 2015 and is shown for comparison in all panels.

Time series of daily ice concentration in the study area for different decades from January-1 through Dec.-31 for each year from 1980 through 2015. Panels are sorted by decade. The red curve is for 2015 and is shown for comparison in all panels.

The story here is well-known to anyone interested in Arctic sea ice and climate change, but here it applies to a tiny spec of ocean between the 100 and 1000 meter isobath where we plan to deployed ocean sensors for a year in the fall of 2016. For the two decades of the last century, the ice cover looks like a crap shoot with 80% ice cover possible any month of the year and ice-free conditions unlikely but possible here or there for a week or two at most. The situation changed dramatically since about 2000. During the last six years our study area has always been free of ice from late August to early October, however, our 2016 expedition is during the transition from ice-free October to generally ice-covered early November, but, I feel, our saving grace is that the sea ice will be thin and mobile. I thus feel that we probably can work comfortable on account of ice for the entire period, but the winds and waves will blow us away …

Weather will be most uncomfortable, because fall is the Pacific storm season. And with little or only thin ice, there will be lots and lots of waves with the ship pitching and rolling and seeking shelter that will challenge us from getting all the work done even with 7 days for bad weather built into our schedule.

I worked in this area on larger ships in 1993, 2003, and in 2004. Here is a photo that Chris Linder of Woods Hole Oceanographic Institution took during a massive storm in the general vicinity in October of 2004. The storm halted all outside work on the 420 feet long USCGC Healy heading into the waves for 42 long and miserable hours:

Icebreaker taking on waves on the stern during a fall storm in the Beaufort Sea in October 2004. [Photo Credit: Chris Linder, Woods Hole Oceanographic Institution]

Icebreaker taking on waves on the bow during a fall storm in the Beaufort Sea in October 2004. [Photo Credit: Chris Linder, Woods Hole Oceanographic Institution]

Oh, I now also recall that during this four-week expedition we never saw land or the sun. It was always a drizzly gray ocean on a gray horizon. The Arctic Ocean in the fall is an often cruel and inhospitable place with driving freezing rain and fog.