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 (WA) using daily output
from RACMO2 model and reanalysis data (1979-2016). Empirical Orthogonal
Function analysis of geopotential height anomalies (at 850 hPa) reveals
that the dominant drivers of atmospheric variability over WA are the
Southern Annular mode (SAM), PSA-patterns associated with Amundsen Sea
low (ASL) and El Nin˜o-Southern Oscillation (ENSO), and atmospheric
rivers (ARs). Overall, 93.7% of days with extreme precipitation at the
2 coastal stations of ASE are associated with these patterns. ASL is the
main driver of extreme precipitation over ASE (associated with 44.75%
of extreme precipitation days) followed by PSA-1/ENSO (22.16%), ARs
(21.1%) and SAM (12%). ASL is the main driver of extreme precipitation
in all seasons except summer when ARs are dominant. Extreme
precipitation linked to ASL and ARs are more intense (by ∼ 2 mm/day)
than the rest.