I love watching the opening of a polynya in satellite data. This is North Water at the NW tip of Greenland expanding over 6 days. You can see the wind is to the SW and it is both pushing the mobile sea ice away from the fast ice of Nares Strait (the strait is named for George Nares), and the growth of new sea ice.
This is the location of North Water. It is a famous polynya and important for the local wildlife and first peoples.
The image below from the 14 May 2018 shows streaks of frazil ice. So what you can see is as well as the wind pushing the sea ice away from the fast ice, new sea ice is being generated.
There is a lot happening at the edge of the Greenland Ice Sheet as summer progresses, and the MODIS sensor on the TERRA and AQUA satellites is a wonderful way to observe it.
I noticed the other day (8 July 2015) this beautiful image of fast ice breaking out of a Fjord on the east coast at 76N
The full image can get down to 250 m per pixel and it is amazing stuff. The image below (from Google Earth) shows the location.
And now in the 9 July MODIS image you can see very many large pools of water on the edge of the Greenland Ice sheet. Again, remember each pixel of this image is 250 m across - they look small but that are large pools.
I very much like looking at the AQUA and TERRAMODIS sensor images every now and then. Today I saw this beautiful image off the southern tip of Greenland which was captured on 23rd February 2015.
What you are looking at are three different white things: snow on Greenland, clouds and my favorite of course, the sea ice. You may find it hard to pick out the different white features. This is because it is a true colour image.
In 2012 I put together a storify using twitter and weblinks about the Greenland Surface Melt. In that story a bunch of climate scientists and I talked about whether the extreme melt seen in 2012 was a signature of global warming.
It is a clear and well written paper that shows using MODIS (Moderate Resolution Imaging Spectroradiometer) data from satellites that you need two things for a serious surface melt event: atmospheric blocking (which allows warm air from the south to go over Greenland) + warm surface temperatures.
The event in 2012 had both of those conditions whereas 2013 did not. The difference is striking in their Figure 1.
Their data set allows them to go back to 2000 and construct annual time series.
They find all of the features Ruth pointed out (shown in their Figure 4).
"that June-July 2007 had the most blocking days but did not have the largest melt, although 2007 has been identified as a large melt year in a seasonal sense"
The reason it did not have as much surface melt as 2012 is because the air temperatures brought over the ice sheet by the atmospheric blocking "barely reached 1.5 SDs [above the summer average temperature]". (SDs means standard deviations - basically a measure of how variable the temperature is about the mean.)
In 2012 the atmospheric blocking brought in "a long-lasting anomaly of 2–2.5 SDs [above the summer average temperature]". This is a bit bland but 2.5 SD's in this data set corresponds to temperatures ~6°C or greater above the summer average on the surface of Greenland. That is why the melt in 2012 was so large.
Häkkinen et al. (2014) make no comment in the paper about the future, or the impact of anthropogenic climate change on such events over Greenland. Looking at various assessments of the scientific literature (e.g the Arctic Report Card) we may draw our own conclusions about whether to expect more of these melting events.
[This is a post bringing together things I have done elsewhere whilst learning how to use this platform.]
Back in July 2012 the global news media went very big on a story on the Melting of Greenland.
I got involved in a discussion on twitter about it, with lots of context and decided to have a go at seeing if I could put together a “storyify” on it using the contributions of a wide range of outstanding climate scientists.