Just a quick post on on of the elements I've looked at while trying to improve prediction for the summer. This comes with a caution, because the method outlined only 'predicts' two recent sea ice summer loss events, the 2007 and 2012 crashes. Time will tell whether it is of any use in the future.
Compactness is the ratio of area / extent. Looking at compactness in the Arctic Ocean and the Peripheral Seas (Beaufort, Chukchi, East Siberian Sea, Laptev), and using two periods, June average and Late June average (10 to 30 June); here is a graph of the four indexes.
The Peripheral region shows a greater variation of compactness for both June and Late June, so I will focus on that. The Late June shows a greater variation than for the whole of June, and shows the possible utility of this idea. For those suspecting a link, this is indeed related to the 'June Cliff' in area.
My suggestion is to keep an eye on 10 to 30 June average compactness for Beaufort Sea, Chukchi Sea, East Siberian Sea, Laptev Sea. In 2007 and 2012 compactness for late June fell to around 0.7, unusually low for the 1979 to 2014 period. 2007 and 2012 were both years in which new records of low September extent were set. But it is not new records per-se that I am looking for, rather years of very low September extent. So in summary:
If June 10 to 30th average compactness for the Peripheral Seas of the Arctic Ocean Basin is around 0.7 for a given year, a large summer melt can be anticipated, but is not guaranteed, over the following summer.
For completeness: Here are the new records in NSIDC September Extent and the Peripheral Late June index.
I did say likely, not guaranteed. ;)