If you want to know where you're going, it helps to know where you're coming from. This also goes for Arctic sea ice. Even though the long-term trend is down, it's difficult to tell what will happen in any given melting season. Two things can help us get an idea: initial sea ice state and subsequent weather conditions. This post is about how the sea ice has fared throughout the freezing season and what shape it was in last month when sea ice growth slowly came to a grinding halt and winter started to make way for spring.
For that I'm going to compare the 2014/2015 freezing season with those of the preceding three winters, just like I did last year. That way we can see how the past winter compares to the winters preceding the 2012 record smashing melt and the two rebound years following it. If you want to compare some of the images below with other freezing seasons, you can dig through the 2011/2012 and 2012/2013 winter analyses. And click on the images if you want to have a closer look.
We kick off with the AARI ice age maps for the end of April that show the amount of multi-year ice (MYI) in the Arctic (brown colour):
Last year's genetically modified rat has been replaced by a woolly mammoth (I'm sorry, I can't help but seeing animals in these maps), but the amount looks about the same. What is interesting this year is that the MYI looks a lot more fragmented on the Pacific side of the Arctic, with some young ice (pink) and even open water in the Chukchi Sea.
This has everything to do with a cracking event that took place a couple of weeks ago. It wasn't as spectacular as the cracking event of February/March 2013, but it was still quite big, and more interestingly, it took place at the very end of the freezing season. We have to wait and see if there's any consequence for the melting in this region. On the one hand there's a lot of first-year ice (FYI) between the MYI floes which could melt out early. On the other hand heat might be released to the atmosphere, cooling the water below the ice, making it more resistant to melting.
Either way, it's visible on different maps, such as the ASCAT radar images. Here's a comparison for day 109 (April 19th):