Impacts of atmospheric and oceanic factors on monthly and interannual variations of polynya in the East Siberian Sea and Chukchi Sea

As a key region of Northeast Passage, the polynya along the Siberian coast in the East Siberian and Chukchi Seas is important to local dynamic and thermodynamic processes, sea ice production and marine ecosystem. The detailed variations of polynya and the contributions of atmospheric and oceanic factors to the polynya have not been explored quantitatively. AMSR-E satellite data from January to April during the period 2003-2011 were used to study the impacts of wind stress and ocean heat transport on variations of polynya in the East Siberian Sea and Chukchi Sea. The study region was divided into six domains. Four sets of AMSR-E data with resolutions of 6.25 km and 12.5 km were compared based on two algorithms of sea ice concentration (referred to as 6.25 km-IC and 12.5 km-IC) and sea ice thickness (referred to as 6.25 km-h and 12.5 km-h). The monthly and yearly polynya areas in the four cases and six domains had remarkable differences. The two cases of 6.25 km-h and 12.5 km-h had larger areas of polynya than the other two cases of 6.25 km-IC and 12.5 km-IC. The difference in polynya area between the 6.25 km-h and 12.5 km-h cases was much smaller than the difference between the 6.25 km-IC and 12.5 km-IC cases. The study of atmospheric and oceanic mechanisms on polynya is influenced significantly by the sensitivity of polynya areas. In general, the impact of wind stress and ocean heat transport on the polynyas had noticeable monthly and interannual variations and was dependent on the locations of the polynyas. The alongshore and offshore wind had stronger correlations with the polynya area than ocean heat transport. Although the higher resolution (6.25 km) AMSR-E data are best for the study of atmospheric and oceanic impacts on polynya area, the coarse resolution (12.5 km) AMSR-E data based on sea ice thickness can also be used. Wind direction dominated the polynya area in the East Siberian Sea and wind speed dominated the polynya area in the Chukchi Sea. The variation in ocean heat transport was influenced mainly by variation in volume transport rather than variation in water temperature.