Long-term observatinns of precipitating clouds were carried out by a vertical pointing radar and plan-position indicator PPI) radar at Syowa station (69.0°S, 40.5°E), Antarctica, in 1989. The observations revealed that there were three abundant snowfall seasons at Syowa station and the amount of snowfall was uniform in all seasons except summer. The amounts of precipitation in autumn, winter and spring were 74, 74 and 53 mm (liquid water equivalent), respectively. The amounts of precipitation in autumn and winter were large at Syowa station in 1989. However, the amount of precipitation on the inland ice is expected to be small in winter, indicated by the distributions of precipitation measured by the PPI radar.
The occurrence frequencies of cloud vortices which brought snowfall to Syowa station increased in the autumn and spring seasons, corresponding to the activity of the circumpolar trough. However, the activities ofcloud systems that bring precipitation weaken in Spring when the sea-ice area expands to low latitudes, because of a lower supply of heat and vapor. Thus the activities of cloud vortices are also weakened above the sea ice.