Multi-year measurement of Terra Nova Bay winter polynya extents

This paper presents a five-year measurement of Terra Nova Bay (TNB) polynya extents. The study covers five consecutive austral winters (2005-2009) for the period April 1 - September 30. The polynya area measurement is based on a methodology which makes use of the Sea Ice Concentration (SIC) maps, derived from AMSR-E. The SIC threshold to discriminate between open water and sea ice was set at 70% and its validity was checked by comparing, for selected dates, the polynya area measured with ASAR WS images. The plots of polynya extents clearly reveal two different kinds of polynya events: a short (2-3 days) one and a long-lasting (10-15 days) one. The mechanisms underlying these two kinds of polynya will be further investigated in successive papers by simulations with an atmospheric model and by correlation with wind and air temperature from ground measurements.