KenMankoff

Ice Melts

Nature’s best thermometer, perhaps its most sensitive and unambiguous indicator of climate change, is ice. Ice asks no questions, presents no arguments, reads no newspapers, listens to no debates. It is not burdened by ideology and carries no political baggage as it changes from solid to liquid. It just melts.

– Henry Pollack, PhD.  A World Without Ice.

GLIMMER Ice Shelf Modeling (OS X HowTo)

A new beta version of the Community Ice Sheet Model, Glimmer-CISM, has been released. Below are instructions to compile and run it on OS X.

# build NetCDF
export CFLAGS=-m32
export FFLAGS=-m32
./configure --prefix=/Users/mankoff/local/netcdf-4.1.1 \
          --disable-cxx --disable-curl  --disable-dap
make && make install
say netCDF done

# build GLIMMER
cd ~/local/src/
wget http://download.berlios.de/glimmer-cism/glimmer-1.7.0.tar.gz
tar zxvf glimmer-1.7.0.tar.gz
cd glimmer-1.7.0/

# OS X has issues with 32 and 64 bit libraries.
# The -m32 flag forces 32 bit compilation.
# The following should be one long line:
./configure --prefix=/Users/mankoff/local/glimmer-1.7.0 \
     --with-netcdf=/Users/mankoff/local/netcdf-4.0.1 \
     FC=gfortran F77=gfortran CFLAGS=-m32

make
make install
say GLIMMER done

There are a few ways to test the installation. The source folder provides a test folder:

export PATH=/Users/mankoff/local/glimmer-1.7.0/bin:$PATH
cd ~/local/src/glimmer-1.7.0/tests/shelf
python circular-shelf.py circular-shelf.PP.config
python confined-shelf.py confined-shelf.PP.config
say GLIMMER Test Done # Takes a while. Turn up your volume

Running the above command will result in NetCDF files being created in the output/ subdirectory. You can view the contents of example.nc with most any generic NetCDF viewer. While theses tests run over a given period of time, the output only has one time stored. If you want to see an evolution of the ice shelf, older test suites available from the previous code repository site should be used:

cd ~/tmp/
wget http://forge.nesc.ac.uk/download.php/200/glimmer-example-0.6.tar.gz
tar zxvf glimmer-example-0.6.tar.gz
cd glimmer-example-0.6/
~/local/glimmer-1.7.0/bin/glide_launch.py ./example.config
say done

Examine the output file example.nc to see ice sheet evolution over time. Basal melt is shown below:

@article{Rutt:2009,
  Author = {Ian C. Rutt and Nicholas R. J. Hulton and Antony J. Payne},
  Title = {{The Glimmer community ice sheet model}},
  Year = {2009}}
  Journal = {J. Geophys. Res.},
  Volume = {114},
  Number = {F2},

Iceland’s Root

Iceland's Root

Image appears to be related to Wolfe et al. (1997). Also available in Schubert and Turcotte below the discussion. Image found at LDEO.

More Photos from Antarctica (LMG09-09)

I’ve finally gotten around to uploading some photos from the latest trip to Antarctica. We sailed on the Laurence M. Gould through the Drake Passage and the Bellingshausen Sea, then along the Antarctic Peninsula to Palmer Station. We saw a lot of ice and some wildlife.

If you want to read about the trip you can do so here or by clicking on the LMG09-09 tag to the right.

If you were on the ship here is a GPX file so you can geotag your own photos.

Phosphorescing Sea Ice

This footage was shot by Harriet Mankoff on September 22nd 2009 in the Drake Passage near 60 degrees South. It shows what I have labeled “phosphorescing sea ice” due to the white flashes at the wave crests. The sea is covered by pancake ice and slush. At the wave crest the slush builds up enough that the water drains out of the slush and it looks brighter. The reverse happens in some of the troughs.

Pancakes

Pancake Ice on Waves, Drake Passage, Antarctica.
(61 29.95S, 62 24.68W)

Sun{rise,set} over Sea Ice

We have been sailing home at 9-10 knots for the past few days and will continue to do so for the next 130ish hours.
 
The waypoint computer shows we have about 114 hours and 1050 nautical miles to our next waypoint, which is the entrance to the Straits of Magellan, still about 24 hours from port.
 
Current location is lat: -63.427, lon: -99.812

Ice Tethered Profiler

Yesterday was different. We parked the boat in some fast ice (ice locked to land) and had an ice party. We put out the gangplank and were allowed off the boat. Penguins came over to inspect us.
 
The reason for this was we needed 12 hours to deploy an Ice Tethered Profiler (ITP), and Ice Mass Balance (IMB) system, and take an ice core. The ITP sits on multi-year ice that will hopefully last another year or two in the current location. Hanging off the ice/buoy is a 750 m tether and a small robot that once a day climbs up and down the tether collecting oceanographic data. Each day it communicates via an inductive modem to the surface base which sends it home via Iridium modem. You should be able to see the buoy we deployed here: http://www.whoi.edu/itp
 
The ship crane lowered several hundred pounds of equipment onto the ice including a snowmobile. A route was scouted almost three miles away from the boat, and we towed all the gear out there. The ITP deployment design allows two people with just a wrench and a screwdriver to deploy a ~ 400 pound anchor and ~750 m cable (also weighing hundreds of pounds). Photos will come later.
 
While we set up the ITP another team installed an Ice Mass Balance system. The IMB is a sensor suite that measures approximately the top meter of water, the ice and snow from water to air, and then the top meter of air. It gives a complete picture of the ice-ocean-atmosphere interface. Couple that with the ~800m data from the ITP and it is quite an impressive data set.
 
It was nice to get off the boat for 10 hours and to do some hard physical labor. And while we worked we watched the nose and gigantic soft black eyes of a seal that used our ice holes as a breathing hole.

PIG Micro

Image is approximately 5 mm across. See recent post “PIG Macro” to compare and contrast scales.

Another Iceberg