Very late wrap on my 2013 sea ice season guesses, but, as I was thinking in early August, the straight statistical one busted pretty badly. The observed (NSIDC) September Average sea ice extent was 5.35 million km^2. The guesses were:
The original outlooks (end of May) were:
3.9 million km^2 -- Grumbine, Wu, Wang statistical
4.1 million km^2 -- Wu, Grumbine, Wang model-based
4.4 million km^2 -- Wang, Grumbine, Wu model-based statistical
The end-June Wu et al. estimate was 4.7 million km^2.
The end-July Wu et al. estimate is 4.57 million km^2.
As I suggested then, I'm going to get back in to the statistical approach to try to fix it up. While we don't expect excellent estimates from it, if it's using a sound basis, it shouldn't be wrong by this much. I have some ideas on how to do it.
Still, better estimates than Stephen Goddard's end of August (the 26th) prediction -- Doubling of Arctic Ice in 2013. Doubling September 2012 would have meant 7.26 million km^2. (I was just touring web sites, and saw this article, which reminded me that I hadn't posted the evaluation of my forecasts.)