Analysis of the record-breaking August 2021 rainfall over the Greenland Ice Sheet

Tingfeng Dou, Zuowei Xie, Jason E. Box, Qing Yang, Yifan Yang, Shiwen Teng, Gaojie Xu, Chao Liu, Xichen Li, Derek Houtz, Xun Gong, Zhiheng Du, Minghu Ding, Yongqiang Yu, Cunde Xiao

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Rainfall was witnessed for the first time at the highest area of the Greenland Ice Sheet on 14 August, 2021. The thermodynamic mechanisms supporting the rainfall are revealed by ERA5 reanalysis, in-situ and satellite data. We find that a strong southward intrusion of the polar vortex favored the maintenance of a deep cyclone over Baffin Island and an amplification of anticyclonic circulation over the southeastern ice sheet, which pumped warm and moist air toward Greenland from anomalously warm waters south of Greenland. Across a wide swath of the ice sheet, atmospheric uplift maintained above-melting and rainfall conditions via condensation and enhanced downward infrared irradiance. Without the low-level liquid clouds, the spatial extent and duration of the rainfall would have been smaller. Over the ice sheet topographic summit, the air temperature from the ground to 250 hPa level was ~2 °C higher than the previous record set on 12 July, 2012. Such events may occur more frequently with the decreased temperature contrast between the Arctic and the mid-latitude regions that drives highly amplified jet streams. Thus, this extreme event serves as a harbinger of a more likely wet surface condition across all elevations of the ice sheet.

Original languageEnglish
Pages (from-to)165-176
Number of pages12
JournalAdvances in Polar Science
Volume34
Issue number3
DOIs
Publication statusPublished - 2023

Keywords

  • Greenland Ice Sheet
  • liquid cloud
  • polar vortex
  • rainfall

Programme Area

  • Programme Area 5: Nature and Climate

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