SEASONAL-VARIATIONS OF THE ANTARCTIC COASTAL OCEAN IN THE VICINITY OFLUTZOW-HOLM BAY

During the period of 1990-1992, year-round oceanographic observations were conducted in the vicinity of Lutzow-Holm Bay, East Antarctica. It -was found that the thickness of the Winter Water (WW) layer, characte rized by a cold fresh oxygen-rich water, exhibits its maximum in the a ustral fall (typically 500 m) and its minimum in the austral summer (t ypically 350-400 m). The associated density variation of the water col umn explains only about one third of the seasonal variations in sea le vel at the coast, which suggests a large seasonal variation in barotro pic coastal flow. Prominent freshening occurs in the WW layer during f all. This appears to be caused by the accumulation of WW, whose upper portion is freshened in the preceding summer. These seasonal variation s appear to occur every year. We propose that the seasonal variation i n the WW layer is mainly caused by the seasonal variation in the wind over the coastal ocean. In fall the prevailing easterly wind intensifi es, which increases the Ekman convergence of WW in the coastal ocean, while in summer the opposite occurs.