INVESTIGATION OF THE RELATIONSHIP BETWEEN RECENT WARM WINTER SURFACE TEMPERATURES AND GLACIAL MELTING IN SVALBARD AND THE RUSSIAN HIGH ARCTIC

The Arctic has experienced record breaking average surface temperatures in the last several years, including 2015 and 2016. This study uses microwave remote sensing to examine the impacts of these recent high surface temperatures on the melting of the glaciers and ice caps in Svalbard and the Russian High Arctic (RHA). Datasets utilized were the (passive microwave) Special Sensor Microwave Imager/Sounder (SSMIS), which has a 25 km resolution using EASE-Grid, and the Brigham Young University (BYU) enhanced resolution data from the (active microwave) Advanced Scatterometer (ASCAT), which has a 4.5 km gridded resolution. Based on the winter (January-March) average sensor data, melt threshold was defined for each pixel in the study area. If the threshold was passed within a pixel, this indicated that the pixel area was experiencing melting. For SSMIS, melting occurred when brightness temperature moved above the threshold; for ASCAT, melting occurred when microwave backscatter dropped below the threshold. Using this method, the melt onset date (MOD) and the total melt duration (TMD) of the 2015 and 2016 ablation seasons in Svalbard and the RHA were determined for ASCAT and SSMIS data. These were compared to previous years’ individual and average MOD and TMD in order to determine the extent to which summer glacier melt was enhanced. Next, this study examined anomalous warm events that occurred outside the ablation season, in particular a winter storm with above zero Celsius temperatures that occurred in December 2015, and the timing and extent of the resulting melt were calculated. Regional melt results were compared to datasets that included sea surface temperature from the Moderate-resolution Imaging Spectrometer (MODIS) and sea ice extent from the National Snow and Ice Data Center (NSIDC). This study helps us understand the sensitivity of high latitude glaciers to unusually warm and variable winter temperatures.