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Contribution of Atmospheric Rivers to Antarctic Precipitation - PubMed

  • ️Sat Jan 01 2022

. 2022 Sep 28;49(18):e2022GL100585.

doi: 10.1029/2022GL100585. Epub 2022 Sep 14.

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Contribution of Atmospheric Rivers to Antarctic Precipitation

Michelle L Maclennan et al. Geophys Res Lett. 2022.

Abstract

Atmospheric rivers (ARs) are efficient mechanisms for transporting atmospheric moisture from low latitudes to the Antarctic Ice Sheet (AIS). While AR events occur infrequently, they can lead to extreme precipitation and surface melt events on the AIS. Here we estimate the contribution of ARs to total Antarctic precipitation, by combining precipitation from atmospheric reanalyses and a polar-specific AR detection algorithm. We show that ARs contribute substantially to Antarctic precipitation, especially in East Antarctica at elevations below 3,000 m. ARs contribute substantially to year-to-year variability in Antarctic precipitation. Our results highlight that ARs are an important component for understanding present and future Antarctic mass balance trends and variability.

Keywords: Antarctica; atmospheric rivers; detection; ice sheet mass balance; precipitation; surface mass balance.

© 2022. The Authors.

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Figures

Figure 1
Figure 1

Mean precipitation rate as a function of time after atmospheric river (AR) passage, expressed relative to the last time step of AR passage, on the Antarctic Ice Sheet (AIS) for the year 2019. The thick black line denotes the mean of all ARs on the AIS, and the thin black lines show results for each individual glacier drainage basins (Shepherd et al., 2012). The vertical red line and shading show the 24 ± 6 hr time window that we have selected as the most suitable period to present our AR precipitation results. For clarity, this period can visually be interpreted using this figure: we include all times on the left side of the red line/shading to AR precipitation, and any precipitation on the right side of the red line/shading is excluded.

Figure 2
Figure 2

(a) 1980–2020 average precipitation attributed to atmospheric rivers (ARs) (mm w.e. per year); (b) 1980–2020 average relative contribution of AR precipitation (as shown in (a)) to the total annual precipitation; (c) Time series (1980–2020) of total Antarctic Ice Sheet (grounded ice sheet and ice shelves) AR precipitation (black, in Gt yr−1), and relative contribution of AR precipitation to total precipitation (in red, in %). The delineations of the drainage basins that are used further in this study are shown in thin black lines, and the grounding line and ice shelf boundaries are shown in thicker black lines.

Figure 3
Figure 3

Annual Antarctic Ice Sheet (AIS) atmospheric river (AR) precipitation (1980–2019, horizontal axis) versus (a) annual AR frequency (1980–2019) on the AIS, defined here as the relative time an AR exists anywhere on the AIS; and (b) Annual mean (1980–2019) AR strength, approximated here by the mean IVT maximum found in all Antarctic ARs during each year.

Figure 4
Figure 4

Relative contribution of atmospheric river (AR) precipitation to (a) the 1980–2019 average total precipitation; (b) the 1980–2020 interannual variability, defined as the percentage of explained variability of the best (positive) linear correlation between detrended annual AR and total precipitation; (c) the 1980–2019 relative change in total precipitation, with the dots showing relative change in AR precipitation (with same color scheme as for total precipitation, and size proportional to relative change). Note that basins that partly cover >85°S only include those areas <85°S in this analysis.

Figure 5
Figure 5

Relative contribution of atmospheric river (AR) precipitation to total precipitation (solid blue; left axis), and total precipitation variability (dashed red; right axis), as a function of elevation. The thick line shows the average of all basins, and the band indicates twice the standard deviation across all basins.

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