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Abstract:
Although crucial for the ice cap surface mass balance, precipitation remains poorly characterized over Antarctica, even less so in complex terrain influencing the local circulation. In this study, one summer month of measurements collected by a transect of three vertically-pointing radars (MRR-PRO) has been used to investigate the spatial variability of precipitation in complex terrain in the vicinity of the Belgian base Princess Elisabeth Antarctica.
The occurrence of surface precipitation and virga at the three MRR-PRO locations has been studied, revealing that virgae represent a lower fraction of the total precipitation at higher altitudes.
The analysis of the reflectivity profiles suggests that sublimation is predominant below 3.5 km above mean sea level, regardless of the altitude of the considered site. High-resolution simulations from the WRF model (forced by ERA5 data) show lower values of relative humidity with respect to ice in the same section of the profile. The depth of this sub-saturated layer depends on the terrain height, resulting in the enhancement of sublimation in the lowest locations of the transect. The ERA5 reanalysis and WRF simulations also suggest that orographic lifting takes place during precipitation events, increasing the total snowfall above the highest mountain peaks.
Finally, the analysis of the succession of virgae and surface precipitation above the three sites indicates that surface precipitation is predominantly associated with a low-pressure system located directly south of PEA, over the Southern Ocean. Low-pressure system locations further to the West or East result in virgae that, respectively, precede and follow surface precipitation.
