The influence of orographic gravity waves on precipitation during an
atmospheric river event at Davis, Antarctica
Intense snowfall sublimation was observed during a precipitation event
over Davis in the Vestfold Hills, East Antarctica, from 08 to 10 January
2019. Radar observations and simulations from the Weather Research and
Forecasting model revealed that orographic gravity waves (OGWs),
generated by a north-easterly flow impinging on the ice ridge upstream
of Davis, were responsible for snowfall sublimation through a Foehn
effect. Despite the strong meridional moisture advection associated with
an atmospheric river (AR) during this event, almost no precipitation
reached the ground at Davis. We found that the direction of the synoptic
flow with respect to the orography determined the intensity of OGWs over
Davis, which in turn directly influenced the snowfall microphysics.
Turbulence induced by the OGWs likely enhanced the aggregation process,
as revealed by dual-polarization and dual-frequency radar observations.
This study suggests that despite the intense AR, the precipitation
distribution was determined by local processes tied to the orography.
The mechanisms found in this case study could contribute to the
extremely dry climate of the Vestfold Hills, one of the main Antarctic