Description: We conducted Doppler radar observations at Syowa Station in 2021-2022. The main objectives are to assess precipitation amount at Syowa Station and to study the precipitation system associated with a synoptic-scale disturbance. The latter half of this observation period coincided with the second SOP of YOPP-SH, during which enhanced radiosonde observations were conducted. In this presentation, we show the characteristic features of precipitation events associated with synoptic-scale disturbances from these observations. And based on this observation, we will discuss the mechanism of the precipitation system in the coastal areas of the Antarctic ice sheet. The most striking feature shown by the Doppler radar is the presence of a strong wind layer that forms below 1000 m altitude. This wind direction is nearly parallel to the continental topography and may have been formed by topographic blocking caused by the Antarctic ice sheet. Previous studies in other regions have suggested that cooling of the lower atmosphere by sublimation of snowfall is responsible for the enhancement of the system, but the effect on this Antarctic system remains to be determined.

Description: This presentation summarize activities at Syowa Station during the second SOP of YOPP-SH from April to August 2022. This second SOP was primarily intended to capture extreme precipitation events associated with atmospheric river. Observation sites participating in this SOP were divided into two regional groups. They are the Antarctic Peninsula and the East Antarctic region centered on the Ross Sea area, respectively. Syowa Station was incorporated into both plans. Special activities at Syowa Station during the SOP were extra radiosonde observation, reporting of AWS data on the ice sheet to GTS, and X-band precipitation radar observation. There had been another precipitation event at Syowa Station at the same time as the Antarctic Peninsula and Ross Sea area. There was also the capture of pre- and post-system features associated with events in the Antarctic Peninsula and in the Ross Sea area.

Description: Although a decrease in the overall mass of the Antarctic ice sheet has been reported since the 1990s, only the west of East Antarctica has reported an increase in mass since the mid-2000s, with the timing of extreme precipitation events. In the west of East Antarctica, four Automatic Weather Stations (AWSs) have been installed by the Japanese Antarctic Research Expedition along the elevation gradient. In this study, we focus on blowing snow process that affects the surface mass balance of the ice sheet in the west of East Antarctica, where mass gain has been reported. Blowing snow plays a role in redistributing snow once accumulated, and it is not yet clear how extreme snowfalls will be redistributed. We calculated the correlation coefficients between the wind speeds by the AWS installed near the top of the ice sheet and the blowing snow frequency at the same area by ICESat-2 (ATL17, Version 4) using data from January 2022 to July 2022. The results showed that the correlation coefficients were -0.17 (between the wind speeds and the 25 Hz high-rate blowing snow frequency), -0.23 (between the wind speeds and the 1 Hz low-rate blowing snow frequency), and +0.97 (between the 25 Hz high-rate blowing snow frequency and the 1 Hz low-rate blowing snow frequency). Little relationship was found between the wind speeds and the blowing snow frequency during this period. We plan to further investigate the presence of snowfall and snow surface conditions in the west of East Antarctica.

Description: The Japanese Antarctic Research Expedition (JARE) has been conducting snow stakes observation between Syowa Station and Dome Fuji Station for more than 30 years. This observation has revealed interannual variations in the annual depth of accumulation. In order to clarify the cause of this interannual variation from field observation, it is necessary to know the date and time of the snow surface change and its magnitude. Therefore, we have installed four AWSs equipped with snow depth sensors from 2016 to 2019. This presentation shows the main results as follows: 1) The temporal changes of surface height include stepwise fluctuations and pulse-like fluctuations, and the rise in surface height is mainly caused by stepwise rises, rather than pulse-like fluctuations. The stepwise fluctuations are likely associated with synoptic-scale disturbances. The pulse-like fluctuations are concentrated more in cold season than warm season. 2) A slow decline in surface height was observed during the warm season. 3) The stepwise fluctuations in the inland plateau areas are concentrated more in warm season than cold season.