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Communication Dans Un Congrès Année : 2018

Atmospheric River Climatology in Antarctica

Résumé

To properly understand the future Antarctic surface mass balance (SMB) requires a complete understanding of the factors that influence SMB today. Atmospheric rivers, broadly defined as a narrow yet long bands of high precipitable water, provide a sub-tropical connection to the Antarctic continent and are observed to significantly impact the affected region's SMB over short, extreme events. Over coastal Dronning Maud Land, East Antarctica, Gorodetskaya et al. (2013) observed that 4-5 atmospheric rivers contributed to 74-80% of the region's SMB during 2009 and 2011. When an atmospheric river reaches the Antarctic continent, their signature is clearly observed in increased downward longwave radiation, upward vertical motion, temperature, snowfall, surface melt, and moisture transport. Using an atmospheric river detection algorithm designed for Antarctica and applied to ERA-Interim reanalysis data, we assess the frequency of atmospheric rivers and estimate their impact on total snowfall from 1979-2017 over the Antarctic continent. We also found that atmospheric rivers are associated with positive temperature anomalies and have consequences on surface melt, like in interior locations of Adélie Land. There is a weak seasonal trend in atmospheric river activity that is location dependent like in the Wilkes Land region where maximum activity occurs in July. Whether an atmospheric river reaches the Antarctic continent is dependent on the degree of upper-level atmospheric blocking. Atmospheric rivers are associated with significant positive geopotential height anomalies across all regions of Antarctica with the highest anomalies occurring around the Amundsen-Bellingshausen Sea and Adélie Land. Our results suggest that atmospheric rivers should play a significant role in the Antarctic SMB, and that any future changes in atmospheric blocking or tropical-polar teleconnections may have significant impacts on future SMB projections.
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Dates et versions

hal-02402511 , version 1 (10-12-2019)

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Jonathan Wille, Vincent Favier, Francis Codron, Ambroise Dufour. Atmospheric River Climatology in Antarctica. American Geophysical Union, Fall Meeting 2018, AGU, Dec 2018, Washington, D.C., United States. ⟨hal-02402511⟩
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