Tag Archives: Greenland

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It is October and it is the Arctic sea ice growing season. The MODIS imagery yesterday shows this beautiful image of sea ice on the North East Greenland coast.

North West Greenland in a MODIS image 5 October 2016
North East Greenland in a MODIS image 5 October 2016 from the TERRA satellite

The image below shows roughly where we are looking:

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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

Fast ice breaking out of an East Greenland fjord
Fast ice breaking out of an East Greenland fjord

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.

Location of the enlargment
Location of the enlargement

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.

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I very much like looking at the AQUA and TERRA MODIS 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.

Sea ice off Cape Farewell
Sea ice off Cape Farewell, Greenland

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.

But as the MODIS web site says:

[the] detectors measure 36 spectral bands between 0.405 and 14.385 µm, and it acquires data at three spatial resolutions -- 250m, 500m, and 1,000m.

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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.

Greenland melt on the BBC
The original BBC Greenland Melting story

An Open Access paper by Sirpa Häkkinen and others Greenland ice sheet melt from MODIS and associated atmospheric variability, published on 10 March 2014, explains how it happened.

Häkkinen et al., 2014 Greenland ice sheet melt from MODIS and associated atmospheric variability
Häkkinen et al., 2014 Greenland ice sheet melt from MODIS and associated atmospheric variability

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.

Häkkinen et al., 2014 Fig 1
Figure 1 From Häkkinen et al., 2014. Extent of melt on the Greenland ice sheet for (a) 1 January to 31 December 2012 (days 1–366) and (b) 1 January to 30 August 2013 (days 1–243) as determined from MODIS-derived melt maps. A maximum of ~95% of the ice sheet surface (shaded red) experienced some melt in 2012 and only ~49% of the ice sheet surface experienced some melt in 2013. White represents no melting (according to MODIS), and green represent non-ice covered land areas. The location of Summit, mentioned in the text, is shown. Elevation contours are shown at 1500, 2000, 2500, and 3000 m.

Their data set allows them to go back to 2000 and construct annual time series.

And just like Dr Ruth Mottram said in my original storify,

Ruth Mottram Tweet
Tweet used in original storify.

They find all of the features Ruth pointed out (shown in their Figure 4).

They say,

"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.

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[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.

Greenland melt on the BBC
The original BBC Greenland Melting story

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.

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