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Weddell Polynya Watch

Seasonally available, April 1 to October 31


Take a look at the Ross Sea collapse page for interesting Antarctic events from October to March.
color barCurrent Weddell Sea Ice Cover


A polynya is an area of reduced or zero ice concentration.   While they normally do occur annually near coasts and in certain other locations, they tend to be small.  In 1974-1976 a spectacularly large polynya opened in the Weddell Sea, Antarctica.  Since then it has not recurred although much smaller polynyas have been sighted on an occasional basis.

2017 is the first time we've seen some polynya formation in the Weddell Sea since 2000. In 2000, we had no noteworthy polynas in the Weddell Sea.  There was only a small area of reduced ice concentration between approximately 26 August 2000 and 2 September 2000. 2001 through 2016 were even more boring. Not even an attempt to form a polynya.

In 1999, the Weddell Sea was quiet until mid-July. Towards the end of the month, a sizeable area of reduced ice concentration opened up. This was preceded (in time at least) by the formation of a large polynya in the Cosmonaut Sea in early-mid July. Interesting times! 29 July 1999. 4 August 1999: I've got to stop looking at the area. As soon as I wrote the above, the proto-polynya began closing back up. I'll quit looking for a while, so you may find something happening again.

In 1998, while not a full-blown (large area of zero ice) polynya, there was less ice than usual in the Weddell Sea, in the same area as the giant Weddell polynya of the '70's.  Because the polynya is such a spectacular feature when it does occur, we have established this page to make it easier to keep track of the current state of the Weddell Sea ice pack.

The polynya, when it occurs, is quite important for the oceans and the atmosphere.  The sea ice pack acts to insulate the ocean from the atmosphere.  Without this lid, the ocean (temperature near 0 C) is free to give heat to the atmosphere (temperature can be -30 C).  The amount of heat provided to the atmosphere is significant for the atmosphere.  The loss of heat by the ocean results in a cooler, and therefore denser, ocean.  The denser ocean waters can then participate in a stronger deep ocean circulation.

Please see the MMAB Automated Sea Ice Analysis Page for information on how to interpret these figures.

Take a look at the Ross Sea collapse page for interesting Antarctic events from October to March.


Robert.Grumbine@noaa.gov
Last Modified 18 September 2017


Antarctic Sea Ice Animations - Whole Antarctic, by Month

Archive of Daily Weddell Sea Images

Weddell Polynya During 1994 Anzflux expedition


Some Online References

Surveys
SCAR Global Change Program - A Summary of Global Change in the Antarctic
CLIVAR - Ocean Program for Decadal-Century Climate Variability Workshop, 1996
CLIVAR - Southern Ocean Climate Variability includes a nice figure of the major Weddell Polynya of 1974-6

Individual Papers
ERS Satellite Microwave Radar Observations of Antarctic Sea-ice Dynamics, Drinkwater, M.R. and X. Lui, Porc. 3rd ERS Scientific Symposium, 17-20 Mar., 1997, Florence, Italy, ESA Publications Div., ESTEC, Noorwijk, The Netherlands, 1997.

Data Sets
NASA GSFC Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSMI/I Passive Microwave Data. 10/1978-12/1996. 9/1995 to 7/1997
NCEP Sea Ice Archive 9/1995 to present



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Page last modified: Monday, 18-Sep-2017 17:22:22 UTC