Melt pond May alliterates well and the name conveys what it's about: the time when melt ponds first start to form. Luckily, a couple of weeks ago, someone on the forum (forgot who, but thanks!) helped me find a perfect alliteration for June: Junction June. This name refers to the month's importance for the rest of the melting season.
The idea is simple: the fraction of the ice pack's area that is covered by melt ponds during May and June, preconditions the ice for the rest of the melting season, because melt ponds lower the pack's albedo and thus soak up more solar radiation. This in turn increases melting momentum, which can sustain a high decrease during the second half of the melting season, even if weather conditions aren't perfect for melting, compaction and transport. Conversely, if melting momentum is low, chances of new September records are minimal, unless weather conditions during July and August favour huge losses. Hence the word 'junction'. The trajectory for the melting season is largely determined during May and June.
Just like last month, I'll analyse the melt pond situation by comparing this year's weather conditions with those of previous years that generated records (2007, 2011 and 2012) as well as rebounds (2013 and 2014). But first I want to look at the melt pond distribution maps that were sent to me by David Schröder from the University of Reading and are based on his research published last year. A model, using NCEP reanalysis data for atmospheric forcing, simulates the melt pond distribution across the Arctic, and although pond area in May is only around 1% of the total melting season area, this melt pond cover fraction according to Schröder et al seems to have the strongest impact on the sea-ice state in September.
This correlation has been contested in a recent study by Jiping Liu et al, published in Environmental Research Letters back in May. The paper states that "a significantly strong relationship (high predictability) first emerges as the melt pond fraction is integrated from early May to late June, with a persistent strong relationship only occurring after late July." Either way, late June is now well behind us, so here are the melt pond distribution maps for 2012, 2014 and this year (click for a larger version):
Mind you, these maps are model results and don't display the exact locations of melt ponds.
Eyeballing the maps it's clear that 2015 has more melt ponds than 2014, but doesn't come even close to 2012. Dr. Schröder writes: