Seasonal variations of the sea level at Syowa Station

分析了南极Syowa站1979~1988年的海平面记录，研究了海平面的季节变化及其年际变化。这一水平在初冬达到最大值，在仲夏降至最低。变化格局十分偏斜，冬峰平坦，夏季低谷陡峭。秋季的上升速度远大于春季的下降速度。这种变化模式与中纬度地区的海平面变化正好相反，在中纬度地区，海平面的峰值出现在夏末，谷值出现在仲冬。研究了海平面变化与几种海洋气象现象的关系。冬季海平面峰值出现在北太平洋亚北区及其边缘海域，如鄂霍次克海。这是由于冬季海洋表层盐度下降所致。Syowa站附近表层盐度的变化表明，秋季极早期海平面的上升可以用表层盐度的降低来解释，但不能解释这种变化的主要特征。南极东部几个沿海站的Katabatic风速变化也有类似的变化规律。现阶段海平面与Katabatic风速的物理关系尚不清楚，但本研究发现的海平面与Katabatic风速的年际变化规律将为今后的研究提供很好的参考。

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.