Relative contribution of atmospheric drivers to ‘extreme’ snowfall over
the Amundsen Sea Embayment
Abstract
We investigate the atmospheric drivers of extreme precipitation over the
Amundsen Sea Embayment (ASE) of West Antarctica using daily output from
RACMO2 model and re- analysis data (1979-2016). Overall, 93.7% of days
with extreme precipitation at the 2 coastal stations of ASE are
associated with the 4 dominant Empirical Orthogonal Function (EOF) modes
of geopotential height anomalies (at 850 hPa) over West Antarctica. The
second EOF mode, associated with a coupled pattern consisting of
Amundsen Sea Low and a blocking high to the east, is the main driver of
extreme precipitation over ASE, linked to 44.75% of extreme
precipitation days. This is followed by EOF-3 (associated with El Niño
Southern Oscillation/PSA-1), EOF-4 (likely associated with more frequent
‘atmospheric river’ events) and EOF-1 (i.e., Southern Annular mode) with
a contribution of 22.16%, 21.1% and 12%, respectively. Extreme
precipitation linked to EOF-2 and EOF-4 are more intense (by ∼2 mm/day)
than the rest.