month day year ice diff
7 23 2002 8.233281 -0.112188
7 23 2003 8.278125 -0.066094
7 22 2004 8.585156 -0.067032
7 23 2005 7.688906 -0.058750
7 23 2006 7.625000 -0.063281
7 23 2007 6.972031 -0.094375
7 22 2008 7.886875 -0.102969 – prelim
7 22 2008 7.883125 -0.106719 – revised

I always exhort my younger trainee meteorologists to put statistics to one side and look at the facts. There is a very large area of fractured sea ice, and there are FORECAST sustained strong winds. “Melt” is not a significant factor – “compaction” is.

you’re right, but Joshua thought the driver would be strong winds on monday, tuesday and wednesday. Until then 2007 had pretty high daily melts (on average close to 100.000), so it’s unlikely 2008 will gain much before that.

Furthermore I think you’re putting too much dependence on the EWMA. If you look at the raw melt rates of 2003-2007 for the next 7 days, you see but a few spikes, just above 100.000 km. Yes, maybe if the conditions are right 2008 will put a string a 100.000′s on the clocks, but a consistent 150.000 for a week would be beyond unprecedented. It would be a miracle, especially sice 2008 has tracked the 2003-2007 average so well these past months.

Joshua said 7 days, “this time next week”, not three. For seven days the melt rate would have to average 150,000 km2/day to reduce the difference in extent by half. Unlikely. For two weeks it’s 120,000 km2/day and for three weeks it’s 102,000. Longer than that the melt rate in 2007 is beginning to decrease rapidly and catching up is potentially easier but is less likely because by then 2008′s melt rate should be decreasing as well.

The North Pole Webcam has drifted considerably this year and is now at 84N, almost between Greenland and Svalbard.

http://www.arctic.noaa.gov/latest/noaa2.jpg

Position (Purple line).

http://psc.apl.washington.edu/northpole/DriftTrackMap.html

The MODIS satellite pics from the past few days show the icepack within the Arctic Circle is much more solid than it was a few weeks ago.

http://rapidfire.sci.gsfc.nasa.gov/realtime/

I understand that there is group delay in an EWMA plot. However the 2007 curve in the graph has the same alpha as 2008 so the group delay should be the same. I have also plotted the average of 2003 to 2006. That curve has also bottomed before 2008. The difference is small so far and could easily be noise. We’ll know in a week or two.

My pointless forecast (because who really cares if I’m right – and does it make a difference anyway) is that by this time next week the extent deficit will be halved and 2008 will be closing in on 2007. Polynyas in the vicinity of the North pole are not out of the question.

Dewitt…part of the reason for that is that 2008 has had a lot more lower latitude ice left than 2007, such as in Hudson Bay, Greenland Strait, etc. Places like that are eventually going to melt all of the way, and it just has taken longer in 2008. The most important thing to look at, imo, is how much ice remains in the actual Arctic ocean. 2008 clearly has a lot more extent than 2007 in areas that are not guaranteed to melt, and that is a huge advantage, I think.

If you look at the regional breakdown in Cryosphere today you’ll see that except for E Siberia and the Laptev sea everywhere is close to it’s 2007 value. The Laptev sea has about 0.3 million sq km above its 2007 minimum, E Siberia about 0.55 million sq km above its 2007 minimum, these areas are below ~75ºN and still have favorable melt conditions. Most of the remaining ice is in the central Arctic basin (3.2 million sq km) and what happens there will determine whether a record is set or not.
As Stated in NSIDC: “An unusual area of low ice concentration is also developing near 85 degrees North latitude” so it will be interesting to see what happens there.
Yesterday’s data from buoy 07413 at Lat: 84.498 N Long: 142.108 W indicates rapid thinning in that region:

Insolation at the North Pole took over a month to decline from 525 W/m2 down to today’s 450, but the decline rate has now increased to about 5 W/m2 per day. Insolation will fall to 400 around August 2 and then 200 on August 30. Around 200 the outgoing IR is just about in balance with the incoming sunlight and the melt rate is near-zero.

While a late-summer melt may push the 2008 ice minimum down to the 2007 value it is very unlikely that an insolation-adjusted value would fall to the 2007 level.