Spatiotemporal variability of extreme precipitation events and
associated atmospheric processes over Dronning Maud Land, East
Antarctica
Abstract
We investigate the spatial and temporal variability of extreme
precipitation events (EPEs) in the Dronning Maud Land (DML) sector of
Antarctica using high-resolution ECMWF ERA5 reanalysis data. This study
examines the spatial occurrence of EPEs across DML, focusing
particularly on six locations spanning the coastal and interior parts of
the area. The largest snowfall amounts are usually found on
eastward-facing slopes in the coastal zone. EPEs occur predominantly in
north-easterly to easterly flows, leading to enhanced precipitation on
the windward side of the orographic features with a steep gradient. Wind
during EPEs was found to be more directionally consistent in the coastal
area than in the interior. An east-west couplet of a mid-tropospheric
ridge and low-pressure center is essential for steering warm moist
maritime airmasses into the DML region before EPEs. Approximately 40%
of EPEs result from atmospheric rivers (ARs), narrow bands of moist air
originating at subtropical latitudes, which provide the greatest daily
precipitation amounts. From 1979 to 2018, much of the DML experienced a
statistically significant (p < 0.05) increase in the number of
EPEs per year, along with increased precipitation from the EPEs. These
trends were associated with significant changes in moisture availability
and poleward meridional winds in the Atlantic sector of the Southern
Ocean. The inter-annual variability in the number of EPEs is primarily
dictated by regional atmospheric variability, while the influence of the
Southern Oscillation Index and Southern Annular Mode is limited.