Tag Archives: extent

Antarctic sea ice extent remains low compared with the 1981-2010 median extent. This image shows the mean from 1989-93, the extent on 20 November 2017 and the difference between the two. Red colours imply that there is a decreased sea ice extent compared with the mean.

The mean Antarctic sea ice for the years 1989-93 on 20 Nov, the sea ice concentration on 20 Nov 2017 and the difference between the two data sets. Reds imply decreased sea ice compared with the mean, blue shades imply more. The original data come from the DMSP SMMI data set at the NSIDC.
The mean Antarctic sea ice for the years 1989-93 on 20 Nov, the sea ice concentration on 20 Nov 2017 and the difference between the two data sets. Reds imply decreased sea ice compared with the mean, blue shades imply more. The original data come from the DMSP SMMI data set at the NSIDC.

And obvious low region is the vicinity of the Weddell Sea Polynya. I have written about the polynya this season on 17 September and 25 September, as well showing how it developed through the winter on 11 September 2017.

Something exciting is happening in the ocean under the polynya, and based on new data sources such as the SOCCOM buoy that surfaced in the polynya:

Last month, SOCCOM scientists were astonished to discover that a float in the Weddell Sea had surfaced inside the polynya, making contact with satellites in the dead of winter. Its new ocean measurements, transmitted when it surfaced, are being analyzed as part of a study in preparation on Weddell Sea polynyas. With these new observations comes the possibility that the polynya’s secrets may finally be revealed.

We should expect some exciting research articles soon.

Sea ice extent currently ~1.2 million km2 low

The overall sea ice extent is currently ~1.2 million km2 below 1981-2010 median extent. This sounds a lot.

Antarctic sea ice extent (with greater >15% sea ice cover) 18 November 2017. From NSIDC.
Antarctic sea ice extent (with greater >15% sea ice cover) 18 November 2017. From NSIDC.

But at this time of the year the Antarctic sea ice is about to dramatically fall as spring develops. If spring "arrives" early then the extent will - as we see, be relatively low.

Seasonal cycle of Antarctic sea ice extent
Seasonal cycle of Antarctic sea ice extent

Whilst the full on development and opening of the Weddell / Maud Rise Polynya is unusual, if you compare the sea ice on 18 November 2017 with the extent from the same day on 1989-1995 it is clear that the extent is often lower over Maud Rise, at this time.

This is the sea ice on 18 November for 1989, 91, 92, 93, 94, 95 and 18 November 2017. The original data come from the DMSP SMMI data set at the NSIDC.
This is the sea ice on 18 November for 1989, 91, 92, 93, 94, 95 and 18 November 2017. The original data come from the DMSP SMMI data set at the NSIDC.

I will keep watching the sea ice as the summer season develops

MODIS mosaic from the AQUA satellite on 18 November 2017.
MODIS mosaic from the AQUA satellite on 18 November 2017.

** UPDATED 20th November 2017 replacing the first figure from 17  November to 20 November.

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Sea ice continues to be very low in the Arctic this winter. A geographical perspective always helps so here is the status of the sea ice concentration 18 January 2017 compared with the  1989-1993 mean on the 18 January.

RED shades = less sea ice than the 1989-93 mean on 18 January.

BLUE shades = more sea ice than the 1989-93 mean on 18 January.

The mean Arctic sea ice for the years 1989-93 on 18 January, the sea ice concentration on18 January 2017 and the difference between the two data sets. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.
The mean Arctic sea ice for the years 1989-93 on 18 January, the sea ice concentration on18 January 2017 and the difference between the two data sets. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.

A few interesting areas that caught my eye:

Geographic Areas in the Arctic with a strong absence of sea ice on 18 January 2017.
Geographic Areas in the Arctic with a strong absence of sea ice on 18 January 2017.

The first highlight region is the Northern Barents Sea. Sea ice has been very low here all winter, and this situation continues. Because the sea ice has been very late, the polar bears on Svalbard will be impacted, and it has been an issue in Longyearbyen....

Polar bears in Longyearbyen
Polar bears in Longyearbyen.

...continue reading

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The extent and thickness of the Arctic sea ice is decreasing for every month of the year. But looking at straight lines on graphs with a relentless downward trend it’s easy to lose the geographic sense of what is happening.

The red areas in the plot below show where ice was absent on 3 March 2016 compared with the mean 1989-93 at the height of the winter. I chose 1989-93 the comparison period as it is just before the start of the relatively rapid decline in we observe in Arctic sea ice.

The difference between the daily ice extent, in each grid cell and the mean based on historical data for the years 1989-93. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.
The difference between the daily ice extent, in each grid cell and the mean based on historical data for the years 1989-93. Blue shades imply more sea ice and reds imply decreased sea ice compared with the mean. The original data come from the DMSP SMMI data set at the NSIDC.

As you would expect there is not a lot of blue in the plot, and the ice edge has retreated virtually everywhere. The stand out region is the Northern Barents Sea. On the NSDIC website you can see that the decline of sea ice in the Kara and Barents Seas is part of the long-term trend.

...continue reading