Arctic Sea Ice

ASI 2012 update 6: piggy bank

During the melting season I'm writing (bi-)weekly updates on the current situation with regards to Arctic sea ice (ASI). Central to these updates are the daily IJIS sea ice extent (SIE) and Cryosphere Today sea ice area (SIA) numbers, which I compare to data from the 2005-2011 period (NSIDC has a good explanation of sea ice extent and area in their FAQ). I also look at other things like regional sea ice area, compactness, temperature and weather forecasts, anything that can be of particular interest.

Check out the Arctic Sea Ice Graphs website for
daily updated graphs, maps and live webcam images.

July 1st 2012

The ASI update from two weeks ago ended with a couple of questions:

Will the conditions that were so conducive to melting have an inertia-like effect on the SIE and SIA numbers? And what is that big low going to do? Will it tear up the ice pack so we get to see the holes we did in the 2010 melting season? And how about those highs over the Siberian coast during Summer Solstice?

As expected the speedy decrease slowed down considerably, but enough was going on all around the Arctic for the 2012 SIE and SIA trend lines to stay close to the bottom years. That big low-pressure system definitely left a mark all over the Arctic, see for instance the holes in the ice pack on this satellite image for June 26th. It is very reminiscent of 2010, but earlier this time around. And those highs over the Siberian coast? I think they had something to do with SST anomaly charts needing extra colours.

On the day the last ASI update came out, LiveScience had an article about this year's potential new record, with a couple of quotes from the NSIDC's Dr Walt Meier (also known as Saint Walt because of his missionary work in certain corners of the blogosphere):

The tilt of the Earth's axis means the sun does not set above the Arctic Circle on the summer solstice, with summer days growing longer even farther north. As a result, the more dark water exposed to sunlight around this time, the more heat it can soak up.

"In a way it is almost like building up a bank account of heat," Meier said.

Everything is pointing towards a lot of savings in this respect, and interest will probably be high too. But 2012 also has a little piggy bank of melting potential that the other years with low SIE and SIA did not have. While melting very rapidly on the Atlantic side of the Arctic, 2012 decrease is still relatively slow in easy ice places like Hudson Bay and the Greenland Sea. If the weather allows 2012 to break that little piggy bank we will witness another radical nosedive.

All of this and more in ASI update 6.

Daily NSIDC SIE data and graph

Another excellent post from Arctic.io:

Following this step by step guide called Whither Arctic Sea Ice? from the Earth Exploration Toolbook it is possible to download and produce daily NSIDC extent and concentration data.

Designed to familiarize educators and students with techniques for accessing and analyzing sea ice data all necessary steps like applying a look up table or animating the images are explained in great detail.

Walt Meier from the NSIDC contributed expertise from his work and it is worth to carefully read through this fictional case-study.

Continue reading at Arctic.io.

The daily minimum was reached on September 18th: 4.18 million square km. The current SIE number is 4.33 million sqaure km. This graph is now featured on the Daily Graphs page:

Replacement for PIPS ice displacement

I'm still lamenting the fact that the Naval Research Laboratory has pulled the plug from the PIPS 2.0 website. Sure, they were having trouble with their ice thickness maps, but I had hoped they would leave the ice displacement maps in place until the end of this melting season. It was a tremendous help last year in determining whether the fun was over or not. They have new maps out on their ACNFS website, but somehow it's not giving me the same reliable info as the previous, much simpler version. And the AARI ice drift map is only updated on Thursdays for the entire week, which makes it less reliable as the days go by.

Luckily, Arctic.io has been tinkering to find a solution after Robert Grumbine linked to a data set in one of the comment sections here (can't remember which one). He converted the numbers to a map with vectors that can be laid over his Arctic Mosaic map. He made another overlay that consists of the DMI SST map we know from the Daily Graphs page. Together it looks something like this:

As it says in Arctic.io's post:

The drift forecast model visualized here as an overlay on the Arctic mosaic implements this drift law. The model is rather simple, nevertheless the results are pretty good. It provides a forecast of 16 days, shown on the map are the 72 hours forecast vectors.

The National Weather Service's National Centers For Environmental Prediction's Environmental Modeling Center runs this model for decades and it is used by the Anchorage Weather Service Forecast Office and the National Ice Center (NIC).

The relevant science and math of the drift model is explained in this paper: Virtual Floe Ice Drift Forecast Model Intercomparison. I’d like to thank R. Grumbine for his help clearing out some roadblocks during the course of this project.

Read the rest of this post here.

This could come in very handy in those last two weeks of the melting season. Thanks, Arctic.io!

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Update: Arctic.io has told me that you can press the buttons 1 to 6 to get different forecasts for difference days (1 for 1d, 2 for 2d, etc...). Pressing 0 even gets you an animation.

Some more flash melting?

Update September 6th 2011: Some of the ice that was gone in the preliminary map for September 5th returned in the final version. Below to the right there's a new animation that shows maps for the 4th, the preliminary and the 5th.

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Today's preliminary sea ice concentration map from the University of Bremen holds yet another surprise. A large area of low concentration ice has suddenly disappeared in what I refer to as the Laptev Bite, the place where warm waters from the Laptev Sea have been munching their way into the ice pack.

Of course, just as last time, this doesn't mean the ice has totally disappeared. It just doesn't show up on the image because the concentration has gone below the threshold, for whatever reason. And mind you, this is a preliminary map. The definite version might still show a different picture.

Nevertheless, that's quite a bite!

I'm not sure what the reason could be. This time there was only a smallish cyclone passing by, not like that big one from the last flash melting event.

But maybe that was enough to stir the thin ice up.

Let's wait and see what happens next.

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Update:

Here's an ENVISAT radar image of this area for September 5th from Arctic.io: