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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.
 
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 a recurring
basis.
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 and 2002 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 27 September 2002
Monthly Animations Specific to
the Weddell Sea or Polynya Season:
- 2002: No Polynya
- 2001: No Polynya
- 2000
- 1999
- 1998
Archive of Daily Weddell Sea Images
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
Return to Sea Ice Analysis Page
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