It's been out for a couple of days already - and I'm a bit slow - but I want to give it some attention nevertheless: Another mid-month analysis from the National Snow and Ice Data Center. A few snippets, starting with the last bit which I found particularly interesting (Rob Dekker already told us about this buoy site a while back):
Summer melt and sea ice thickness
Data indicate that the Arctic ice cover continues to thin. Sea ice thickness is also an indicator of the health of the ice cover; thick ice is resistant to melt. Specialized buoys managed by the U.S. Army Cold Regions Research and Engineering Laboratory help supplement limited satellite measurements of sea ice thickness. The buoys provide accurate data at specific locations, and can tell us whether thickness changes are due to surface melt, melt at the bottom of the ice floe, or ice growth. These buoys are deployed on thick multiyear ice, which provide long-lasting, stable platforms.
Data from six of these buoys through July 20 show that this year, the ice surface is melting faster than the underside of the ice. As the sun starts to sink on the horizon, surface melt will slow. However, ocean waters warmed during the summer will continue to melt the ice from below, reducing ice thickness and extent into September.
After a period of slow melt from late July through early August, Arctic ice extent is again declining at a brisk pace, but remains higher than for 2007, the record low year. Data also indicate continued thinning of the ice. With about a month left in the sea ice melt season, the amount of further ice loss will depend mostly on weather patterns.
Overview of conditions
As of August 14, 2011, Arctic sea ice extent was 5.56 million square kilometers (2.15 million square miles), 2.11 million square kilometers (815,000 square miles) below the 1979 to 2000 average for that day, and 220,000 square kilometers (84,900 square miles) above the extent on that day in 2007.
Sea ice is low across almost all of the Arctic, with the exception of some areas of the East Greenland Sea. It is exceptionally low in the Laptev and Kara Sea areas.
Arctic sea ice loss slowed down in late July through early August; then over the past week, the rate of ice loss sped up. At present there is more ice than at the same time in 2007, which saw the record minimum September extent.
A change in the weather
During early summer, a high-pressure cell persisted over the northern Beaufort Sea, promoting ice loss. This weather pattern broke down toward the end of July, slowing ice loss but spreading out the ice pack, making it thinner on average. The weather has now changed again, bringing another high-pressure pattern. Winds associated with this pressure pattern generally bring warm temperatures, and tend to push the ice together and reduce overall extent. In the Kara Sea, the combination of a high-pressure cell with low pressure to the west has resulted in strong northward ice movement, pushing the ice pack away from the coast and reducing ice extent. The same weather pattern is also increasing the movement of ice out of Fram Strait, between Greenland and Spitsbergen.