Atmospheric rivers supply ~13% of Antarctic snow
Rare atmospheric rivers deliver about 13% of Antarctic precipitation and explain more than a third of its year-to-year swings.
Source
Contribution of Atmospheric Rivers to Antarctic Precipitation
Study at a glance
- Design
- Other — Polar atmospheric-river detection in MERRA-2 attributing Antarctic precipitation 1980–2020
- N
- 41-year MERRA-2 reanalysis attribution; not a discrete sample N
- Population
- Antarctic Ice Sheet precipitation events classified as atmospheric rivers
- Outcome
- AR share of Antarctic snowfall (~13%) and contribution to interannual variability
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Atmospheric rivers supply ~13% of Antarctic snow
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Relative AR contribution is 16% on East Antarctica and 9% on West Antarctica.
The relative importance of AR precipitation is slightly higher on the grounded ice sheet (14%) than on ice shelves (11%), and higher on East Antarctica (16%) than on West Antarctica (9%) and the Antarctic Peninsula (10%).
What they did
Authors applied a polar vIVT atmospheric-river detector to MERRA-2 (1980–2020) and attributed precipitation inside each AR footprint plus 24±6 hours after landfall.
What they found
ARs supply 374±90 Gt yr−1, 13%±3% of AIS precipitation (higher in East Antarctica than West). They occur <1.5% of the time but explain >1/3 of interannual snowfall variability. AR precipitation is trending up while total precipitation is not.
The limits
What it doesn't show
Results are reanalysis-based, not ice-core validated here; the 24-hour after-landfall window is a choice; poleward of 85°S is excluded.
Key terms
- Atmospheric river
- Long filament of strong meridional moisture transport (vIVT >98th percentile over ≥20°).
- MERRA-2
- NASA atmospheric reanalysis used for precipitation and vIVT.
- AIS
- Antarctic Ice Sheet.
- vIVT
- Meridional integrated water-vapor transport used to detect polar ARs.
- Grounded ice
- Ice resting on bedrock, as opposed to floating ice shelves.
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AIS-wide AR precipitation share:
Common questions
AIS-wide AR snowfall share?
13% ± 3% (374 ± 90 Gt yr−1).
East vs West Antarctica?
About 16% vs 9%.
How rare are ARs?
Frequency does not exceed 1–1.5%.
Trend in AR precipitation 1980–2020?
Significant increase (2.4 ± 1.1 Gt yr−2).
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