Tag Archives: Weddell Polynya

Being interested in the Weddell Polynya I plotted some time series data from 1 September 2017 to 23 November 2017. On the left-hand panel, you can see the see the sea ice concentration, on the right-hand panel, the anomaly of the concentration each day compared with a mean from 1989-93.

The Weddell Polynya is the low concentration region at approximately 12:00 in the movies below.

 

You can see the Weddell Polynya isn’t stationary.

You can also see the sea ice is still relatively low compared to the historic record. We should expect this after the extreme low sea ice from ~October 2016 onward.

Antarctic sea ice extent (with greater >15% sea ice cover) 23 November 2017. From NSIDC.
Antarctic sea ice extent (with greater >15% sea ice cover) 23 November 2017. From NSIDC.

I will write some more about this next week but for interest here is the Antarctic sea ice extent anomaly for 2017.

I made these movies using the excellent Antarctic Mapping Toolbox by Chad Greene. Antarctica is the Landsat Image Mosaic Of Antarctica (LIMA), and the coastline and shelf outlines come from the BEDMAP2 data set. Sea ice data is from NSDIC.

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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Quick post on the Maud Polynya in the Weddell Sea that I wrote about last week. This is the sea ice data 17 September 2017, and the polynya is both clear and large.

The location of the polynya over Maud Rise. Sea ice data from DMSP SMMI.
The location of the polynya over Maud Rise. Sea ice data from DMSP SMMI.

An enlargement of the polynya shows that it is practically open water.

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