CHANGES IN THE ICE-FREE PERIOD IN THE KARA SEA FROM COASTAL OBSERVATIONS

Based on observations for the timing of ice events at 12 coastal stations in the Kara Sea, the longterm means and trends are calculated for start dates, end dates and duration of ice-free period (IFP) for 1979–2020. The obtained results were compared with the calculations for the same IFP parameters based on passive microwave remote sensing data. An increase in the duration of the ice-free period is observed at 9 of the 12 stations considered. This happens both due to the shift of the start dates of the IFP (observed at 8 out of 12 stations) to earlier dates, and due to the shift of the end dates of the IFP to later dates (noted at 11 out of 12 stations). A comparison of long-term means and trends of the start, end dates and duration of the IFP between satellite data and coastal observations confirms that remotes sensing microwave data (sea ice concentration) can be used to analyze the interannual variability of IFP characteristics in the coastal zone of the Kara Sea. It is shown, that the results obtained using the proposed modified threshold method (MPM) are in a better agreement with the coastal observation data than the widely used threshold 15 % method.