Seasonal variations of the sea level at Syowa Station

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The sea level record at Syowa Station, Antarctica for the period from 1979 to 1988 was analyzed, and the seasonal variations of the sea level and its yearly change were investigated. The level reaches a maximum in early winter and falls to its minimum in mid-summer. The variation pattern is very skewed with flat winter peak and sharp summer trough. The ascending speed in fall is much larger than the descending speed in spring. This variation pattern is just opposite to that of the sea-level in middle latitudes, where the peak occurs in late summer and the trough in mid-winter. The correlation of the sea level change with several oceanographic and meteorological phenomena were studied. The winter peak of sea level is observed in Subarctic North Pacific Ocean and its marginal seas such as in the Okhotsk Sea. This is caused by a salinity decrease in the oceanic surface layr in winter. The salinity variation in the surface layr near Syowa Station indicates that the sea level rise at the very early stage in autumn may be explained by the decrease of salinity of the surface layr, but the main feature of the variation cannot explained. The similar variation pattern is observed in speed change of the Katabatic winds at several coastal stations in east Antarctica. Physical relationship between the sea level and the Katabatic wind speed is not clear in the present stage, but the year-by-year change of the variation pattern found in this study will give a good reference to the future investigations.