Application of fluid mechanical technique to the analysis of ice movements in Okhotsuk Sea using satellite millimeter radar images

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Sea ice movements in Okhotsuk Sea were investigated based on millimeter radar images obtained by SSM/I sensors on board DMSP satellite by means of image correlation PIV method. Due to the thick clouds covering the Okhotsuk Sea in winter, investigation of ice via visible light is difficult, but the millimeter radar images can see through the thick clouds and enable us the investigation. 37GHz and 85GHz radar images were obtained from National Snow and Ice Data Center in U.S.A. Then in order to obtain clear images, pinhole noises were eliminated followed by smoothing and elimination of cloud's images on open sea. Using these clear images, ice movement in the past several years were investigated to differentiate the characteristics between years of more sea ice and less sea ice. Then movements of ice in the inner region of ice field and the perimeter were compared by means of correlation PIV to estimate the region of ice production. Also prior to PIV analysis, conditions such as the shape of analyzing matrix were considered, and traceability of present PIV method is compared with tracking results of GPS beacon conducted 1994 to ensure the reliability of present PIV method. As the results, 1) strength of north-westerly seasonal wind was found to determine the amount of sea ice in each year, 2) sea ice was found to form vortex like structure near Hokkaido in every year, 3) ice field near Russian east coast was found to detach from the coast to create open sea region by strong and extremely cold seasonal north-westerly wind, and immediately the sea surface is frozen to create new sea ice.