Polynya Area in the Kara Sea, Arctic, Obtained With Microwave Radiometry for 1979–2003

The polynya signature simulation method is applied to satellite microwave radiometry data to get the mean (January-April) polynya distribution in the Kara Sea for 1995-2004. Temporal variability of polynya location and extent is confirmed with the variability of ERA40 surface wind speeds. The mean (January-April) fraction of ice area of 65%-85% ice concentration relative to the mean daily total Kara Sea ice area agrees well (correlation coefficient: 0.79) with the mean daily total Kara Sea polynya area for 1996-2003. The resulting linear fit is used to extend the polynya area time series until 1979. During 1979-2003, the polynya area increased by 2400 km²/dec. This is accompanied with slightly increasing southerly winds. Polynyas in the eastern Kara Sea seem to play a nonnegligible role for the winter-time Kara Sea ice export.