The Cosmonaut Sea Polynya

The Cosmonaut Sea off Antarctica (~45E 65S) is a region in which anomalously low concentrations of sea ice have been observed during the fall and winter months (Comiso and Gordon 1987).
The most remarkable of these was during the winter of 1980 when an embayment of ice free open water formed in late June and persisted for several weeks before being being enclosed by sea ice and transformed into a polynya. The polyna remained until mid August. At its maximum extent, there was an approximate 130,000 sq kilometer region of open water totally surrounded by ice in the depth of the Antarctic winter!
Several other polynyas have been observed in the Cosmonaut Sea in the intervening 19 years but no sequence of an embayment transforming into a polynya has been identified.
This year, we have identified another embayment in the region in which an approximate 250,000 square kilometer region of the Cosmonaut Sea was anomalously ice free. It has recently been transformed into an open ocean polynya.


Maximum area of ice free embayment during June and July

in the Cosmonaut Sea region for each year from 1979-1999


In 1999, we have observed the largest embayment in the 21 years for which we have continuous data














black solid line: mean over the 21 year period

black dotted lines: one standard deviation above and below the 21 year mean