Relative Contribution of Atmospheric Drivers to Extreme Snowfall Over the Amundsen Sea Embayment

We investigate the atmospheric drivers of extreme precipitation over the Amundsen Sea Embayment (ASE) of West Antarctica (WA) using daily output from the RACMO2 model and reanalysis data (1979-2016). Overall, 93.7% of days with extreme precipitation at the two coastal stations of ASE are associated with the four dominant Empirical Orthogonal Function (EOF) modes of geopotential height anomalies (at 850 hPa) over WA. The second EOF mode, associated with a coupled pattern consisting of an 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 Nino 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 is more intense (by similar to 2 mm/day) than the rest.

Automated summary

We investigated the atmospheric drivers of extreme precipitation over the Amundsen Sea Embayment in West Antarctica. The study found that a coupled pattern consisting of an Amundsen Sea Low and a blocking high to the east is the main driver of extreme precipitation in this region.