Relationship between weather regimes and atmospheric rivers in East Antarctica

Here, we define weather regimes in the East AntarcticaSouthern Ocean sector based on daily anomalies of 700 hPa geopotential height derived from ERA5 reanalysis during 19792018. Most regimes and their preferred transitions depict synoptic-scale disturbances propagating eastwards off the Antarctic co...

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Bibliographic Details
Published in:Journal of Geophysical Research: Atmospheres
Main Authors: Pohl, B, Favier, V, Wille, J, Udy, DG, Vance, TR, Pergaud, J, Dutrievoz, N, Blanchet, J, Kittel, C, Amory, C, Krinner, G, Codron, F
Format: Article in Journal/Newspaper
Language:English
Published: Amer Geophysical Union 2021
Subjects:
Earth Sciences
Atmospheric sciences
Atmospheric dynamics
Antarctic
Southern Ocean
The Antarctic
East Antarctica
Antarc*
Antarctica
Antarctica Journal
Online Access:https://doi.org/10.1029/2021JD035294
http://ecite.utas.edu.au/149043
Description
Summary:Here, we define weather regimes in the East AntarcticaSouthern Ocean sector based on daily anomalies of 700 hPa geopotential height derived from ERA5 reanalysis during 19792018. Most regimes and their preferred transitions depict synoptic-scale disturbances propagating eastwards off the Antarctic coastline. While regime sequences are generally short, their interannual variability is strongly driven by the polarity of the Southern Annular Mode (SAM). Regime occurrences are then intersected with atmospheric rivers (ARs) detected over the same region and period. ARs are equiprobable throughout the year, but clearly concentrate during regimes associated with a strong atmospheric ridges/blockings on the eastern part of the domain, which act to channel meridional advection of heat and moisture from the lower latitudes towards Antarctica. Both regimes and ARs significantly shape climate variability in Antarctica. Regimes favorable to AR occurrences are associated with anomalously warm and humid conditions in coastal Antarctica and, to a lesser extent, the hinterland parts of the Antarctic plateau. These anomalies are strongly enhanced during AR events, with warmer anomalies and dramatically amplified snowfall amounts. Large-scale conditions favoring AR development are finally explored. They show weak dependency to the SAM, but particularly strong atmospheric ridges/blockings over the Southern Ocean appear as the most favorable pattern, in which ARs can be embedded, and to which they contribute.

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