| Summary: | application/pdf As the sea-ice extent decreases during summer over the Arctic, it tends to recover quickly during autumn. I investigated a relationship between the sea-ice recovery and atmospheric circulations over the Arctic in the beginning of freezing season. The object domain is the Pacific sector (70°-90°N, 270°-90°E) in the Arctic Ocean. I analyzed the sea-ice growth rates per day each month (Sep. Oct. Nov.) and the conditions of atmospheric pressure patterns when the sea-ice is generated in autumn from 1979-2010 with ERA-Interim. reanalysis data. The sea-ice growth rates tend to increase recent years. The sea surface atmosphere cold temperature is important for the sea-ice generation. In addition, a cyclone or an anticyclone needs to be located at the cold temperature area. Because the cyclones exist on sea-ice with cold advection to the Arctic ice edge, the upward heat flux from the Arctic Ocean activates the freezing the sea ice. Therefore, the cold air of the lower troposphere and circulations with cyclones or anticyclones on the cold air is needed to generate the sea-ice. Recently, the pressure pattern has changed. The rate of sea-ice generation has increased on October, because signature pressure pattern occurs rather than few decades ago. Additionally, the decreasing horizontal temperature flux roles cooling the Arctic. Both factors affect the much sea-ice generation recent years. 三重大学大学院生物資源学研究科博士前期課程共生環境学専攻 35 thesis
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