The Antarctic ice sheet (AIS) is sensitive to short‐term extreme meteorological events that can leave long‐term impacts on the continent's surface mass balance (SMB). We investigate the impacts of atmospheric rivers (ARs) on the AIS precipitation budget using an AR detection algorithm and a regional climate model (Modèle Atmosphérique Régional) from 1980 to 2018. While ARs and their associated extreme vapor transport are relatively rare events over Antarctic coastal regions (∼3 days per year), they have a significant impact on the precipitation climatology. ARs are responsible for at least 10% of total accumulated snowfall across East Antarctica (localized areas reaching 20%) and a majority of extreme precipitation events. Trends in AR annual frequency since 1980 are observed across parts of AIS, most notably an increasing trend in Dronning Maud Land; however, interannual variability in AR frequency is much larger. This AR behavior appears to drive a significant portion of annual snowfall trends across East Antarctica, while controlling the interannual variability of precipitation across most of the AIS. AR landfalls are most likely when the circumpolar jet is highly amplified during blocking conditions in the Southern Ocean. There is a fingerprint of the Southern Annular Mode (SAM) on AR variability in West Antarctica with SAM+ (SAM−) favoring increased AR frequency in the Antarctic Peninsula (Amundsen‐Ross Sea coastline). Given the relatively large influence ARs have on precipitation across the continent, it is advantageous for future studies of moisture transport to Antarctica to consider an AR framework especially when considering future SMB changes.
High snowfall events on Thwaites Glacier (TG, West Antarctica) are a key influencer of its mass balance, and can act to mitigate sea level rise due to ocean warming‐induced ice loss. We use the output of a high‐resolution regional climate model, RACMO2, in conjunction with MERRA‐2 and ERA5 atmospheric reanalyses for the period 1980–2015 and show that there is a pronounced seasonal cycle in snowfall over TG, driven by the Amundsen Sea Low (ASL). We find that the total annual snowfall does not correlate significantly with the Southern Annular Mode or El Niño Southern Oscillation, but it does relate to the zonal wave three pattern over Antarctica through the coupling of the ASL with a blocking high over the Antarctic Peninsula during high snowfall events. Our results highlight that atmospheric circulation and consequent high snowfall events on TG are highly variable, and recognizing their future change will aid to improve predictions of mass balance.more » « less
- Award ID(s):
- NSF-PAR ID:
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- DOI PREFIX: 10.1029
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- Journal Name:
- Geophysical Research Letters
- Medium: X
- Sponsoring Org:
- National Science Foundation
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