I'll be regularly writing updates on the current sea ice extent (SIE) as reported by IJIS (a joint effort of the International Arctic Research Center and the Japan Aerospace Exploration Agency) and compare it to the sea ice extents in the period 2006-2009. The JAXA graph is favoured by almost everyone, probably because it looks so nice compared to other graphs (like the one by Arctic ROOS, the University of Bremen and the Danish Meteorological Institute). All the years have a nice colour of their own which makes it easy to eyeball the differences between trends. Most of the betting on minimum SIE is based on the IJIS data. NSIDC has a nice explanation of what sea ice extent is in their FAQ.
June 15th 2010
We had to wait four long days for our Japanese friends over at IJIS to update their graph and data file. People were already suggesting we should have a look at other graphs, like this one from the Uni Bremen. But I'm a pretty loyal guy, especially after my router failed me yesterday and this blog had to go for over 12 hours without any update either (with GIF animation problems to boot). So I sympathize with IJIS and I forgive them. Let's hope we don't have to wait as long again when the melting season starts in earnest.
So what has happened in the past few days, now that we have put the period of the 'smoothing of the erroneous blip' - where previously all years would make a little jump - behind us? Of the past four days it was only yesterday that 2010 had the highest recorded melt of the period 2006-2010. 2006 did a bit better and managed to nibble at 2010's lead, but the other years had to concede a few tens of thousands square kilometres in the past few days. 2007, for instance, has a whole week to catch up to get to the total SIE 2010 was at yesterday.
With less than one week to go until the Northern Hemisphere Summer solstice, more or less the starting signal for the melting season, the current difference between 2010 and the other years is as follows:
2006: -242K
2007: -499K
2008: -536K
- 2009: -675K
Interestingly enough 2010 has crept very close to the other years on the Arctic ROOS sea ice extent graph, so currently some quarters of the climate debate blogosphere don't have any graph to watch:
PS looks like channel 5 of the UAH daily temperature plot is having some trouble as well.
TIPS - Other interesting blog posts concerning Arctic ice:
Patrick Lockerby has yet another must-read article over at Scientificblogging, explaining ice mobility, ice quality and the potential future of Arctic summer warming.
I like the DMI graph because they are usually the first to post the data for the current date:
http://ocean.dmi.dk/arctic/icecover.uk.php
The graph is rather small and only goes back to 2005, but you can download it and zoom in if you want to see details better.
The IARC-JAXA graph looks better, goes back to 2002 and now has the "larger image" if you click on the small graph, but my favorite part of this site is their link to past data in numerical form:
http://www.ijis.iarc.uaf.edu/seaice/extent/plot.csv
The NSIDC graphs are nice for the inclusion of ± 2 standard deviations "gray zones" on their graphs:
http://nsidc.org/data/seaice_index/images/daily_images/N_stddev_timeseries.png
They also sometimes publish interesting graphs with multiple years for comparison, e.g.:
http://nsidc.org/images/arcticseaicenews/20100608_Figure2.png
The University of Bremen, Germany, graph is interesting in that it includes data back to 1972:
http://iup.physik.uni-bremen.de:8084/amsr/ice_ext_n.png
The Nimbus 5 ESMR data started from 1972.
Here’s a paper that discusses the Arctic sea ice extent in the 70′s:
http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/6_1/6.1_barry_et_al.pdf
I don't like the Arctic-ROOS site much:
http://arctic-roos.org/observations/satellite-data/sea-ice/ice-area-and-extent-in-arctic
They even get the order of annual graphs different from the other sites, while admitting that they use the same data as NSIDC and U. of Bremen, but might have implemented standard alogirithms "differently":
http://arctic-roos.org/observations/comparison-of-algorithms
Posted by: Anu | June 18, 2010 at 16:05
I agree with you. The csv-file on the IJIS website allows me to track the numbers myself and report the individual differences between years in these reports. And I still think the IJIS sea ice extent graph looks nicest of all graphs out there.
Don't they use data from the SMM/I sensor whereas IJIS, NSIDC and Uni Bremen use the AMSR-E data? Could this account for the differences?
Posted by: Neven | June 18, 2010 at 19:44
Nimbus I satellite data from September 1963 has been retrieved, and is now available in a newly published paper (freely available PDF is here).
Meier, W. N., D. Gallaher, and G. G. Campbell. "New estimates of Arctic and Antarctic sea ice extent during September 1964 from recovered Nimbus I satellite imagery." The Cryosphere Discuss 7 (2013): 35-53.
New results are provided for end of Summer Arctic SIE (about the same as 1979-2000), and end of Winter Antarctic SIE (significantly higher than 1979-2000).
Cheers,
Lodger
Posted by: Artful Dodger | April 16, 2013 at 04:55