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Ice sheets

Atmospheric rivers supply ~13% of Antarctic snow

Maclennan ML, Lenaerts JTM, Shields C, et al. · Geophysical research letters · 2022

Open access · cc by · source: Europe PMC

Rare atmospheric rivers deliver about 13% of Antarctic precipitation and explain more than a third of its year-to-year swings.

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

Structured fields used in claim comparison tables when every cited study has a complete layer.

Key findings

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.

Methodology

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.

Limitations

Results are reanalysis-based, not ice-core validated here; the 24-hour after-landfall window is a choice; poleward of 85°S is excluded.

How this study connects

Role on claims

Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.

  • Atmospheric rivers and moisture fluxes are often defined on a reanalysis grid. A polar vIVT detector on MERRA-2 (1980–2020) attributed 374±90 Gt yr⁻¹, 13%±3% of Antarctic Ice Sheet precipitation, to ARs that occur <1.5% of the time; ERA-Interim moisture fluxes composited with RACMO2 showed PSA1 explaining about 40% of daily West Antarctic precipitation variance.

    Evidence for the claim as stated.

  • Reanalysis precipitation over ice sheets is not interchangeable with ice-core chemistry. AR snowfall shares (13%±3%) are MERRA-2-based and not ice-core validated in that paper; the SH circulation paper uses RACMO2 precipitation, not gauges, and mentions Byrd and Law Dome as geographic extremes. A student who cites both as 'ice-core results' is mixing methods.

    Evidence for the claim as stated.

Open questions

Tensions this paper is part of

From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.

  • Scope difference — different assays, populations, or outcomes

    Reanalysis precipitation over ice sheets is not interchangeable with ice-core chemistry. AR snowfall shares (13%±3%) are MERRA-2-based and not ice-core validated in that paper; the SH circulation paper uses RACMO2 precipitation, not gauges, and mentions Byrd and Law Dome as geographic extremes. A student who cites both as 'ice-core results' is mixing methods.

    Also on this tension

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