Monthly Archives: March 2017

The polynya I saw forming in early February is still clear, and very large in the Southern Weddell Sea. At the moment it is more than than 80,000 km2, although there is clearly a lot of young sea ice covering a large part of the polynya.

The Weddell Sea 5 March 2017 in the Terra MODIS true colour image.
The Weddell Sea 5 March 2017 in the Terra MODIS true colour image.

In my original post I said this was likely formed by winds from the Ronne Ice Shelf.

Well Dr Stef Lhermitte (Delft) has put together the most amazing movie showing the development of the polynya over January and February. It shows satellite sea ice data with winds from the ECMWF overlain.

You can clearly see the winds pushing the sea ice away from the ice shelf as time progresses.

It is just as @StefLhermitte said in his tweet yesterday:

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Trying to understand the geographic nature of the very low Antarctic sea ice extent I made the following animation:

Antarctic sea ice extent on 1 March for the years 1989, 1990, 1991, 1992, 1993, 1994, 1995 and 2017. Data from DMSP SMMI.
Antarctic sea ice extent on 1 March for the years 1989, 1990, 1991, 1992, 1993, 1994, 1995 and 2017. Data from DMSP SMMI.

The highlight issues in the graphic are the clear lack of sea ice in the Amundsen/Ross Seas and the Southern Ocean off Dronning Maud land. (If you are not familiar with the names off the seas / locations see the map below).

The Weddell Sea is has a relatively compressed sea ice cover this year - but it's clear there is large inter-annual variability.

Off Wilkes Land the sea ice is heavier this year - and it's easy for this to get lost in the headline story around the very low extent. There are several Antarctic research stations along this coast:

The French Station Dumont d’Urville,

Two Australian Stations of Casey and Davis,

and the Russian Mirny Station.

Here is the NSDIC Antarctic sea ice extent 1 March 2017.

Antarctic sea ice extent (with greater >15% sea ice cover) 1 March 2017. From NSIDC.
Antarctic sea ice extent (with greater >15% sea ice cover) 1 March 2017. From NSIDC.

And finally the promised map from the National Snow and Ice Data Center (NSIDC) with regional seas and other features marked.

The oceans and regional seas around Antarctica, along with other geographical features. From NSIDC.
The oceans and regional seas around Antarctica, along with other geographical features. From NSIDC.