Most of you will know that since 2013, I use I use the "whiteness" of the Arctic in June as a predictor for how much ice will melt out between June and September.
http://neven1.typepad.com/blog/2013/07/problematic-predictions-2.htmlSpecifically, I use three variables to make this prediction :
- Land snow cover in June
- Ice 'area' in June
- (Extent - Area) in June, which represents the amount of 'water' in the ice pack in June.
A combination of these variables, each one of which affects the 'albedo' of the Northern Hemisphere, represents how much solar energy gets absorbed by the Northern Hemisphere in summer, and this correlates remarkably well with September sea ice cover.
Details of this method is described in one of my entries into Arcus Sea Ice Prediction Network :
https://www.arcus.org/files/sio/25738/sio-2016-july_dekker.pdfThis year, land snow cover in June was quite high compared to recent years :
Also, ice 'area' is quite high in June (in between 2014 and 2015) and the ice is still fairly compact.
As a result, prediction for Sept 2018 September sea ice extent is quite high at 5.19 km
2, with a standard deviation of 340 k km
2.
My gut feeling this year tells me that this an upper bound, but it's fairly clear that given the past performance of this method, it is highly unlikely (less than 2.5% chance) that Sept 2018 will end up below 4.5 M km
2.
Here is what this hind-cast method did for the past 26 years :
Comments and suggestions on this method are welcome in the "Re: Land snow cover effect on sea ice" thread :
https://forum.arctic-sea-ice.net/index.php/topic,292.msg162415.html#msg162415