Preprints
https://doi.org/10.5194/tc-2021-159
https://doi.org/10.5194/tc-2021-159

  26 Jul 2021

26 Jul 2021

Review status: this preprint is currently under review for the journal TC.

Warm and moist atmospheric flow caused a record minimum July sea ice extent of the Arctic in 2020

Yu Liang1,2,3,4, Haibo Bi1,2,3, Haijun Huang1,4, Ruibo Lei5, Xi Liang6, Bin Cheng7, and Yunhe Wang1,2,3 Yu Liang et al.
  • 1Key Laboratory of Marine Geology and Environment, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China
  • 2Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266061, China
  • 3Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266071, China
  • 4University of Chinese Academy of Sciences, Yuquan Road 19, Beijing 100049, China
  • 5Key Laboratory for Polar Science of the State Oceanic Administration, Polar Research Institute of China, Shanghai 200136, China
  • 6Key Laboratory of Research on Marine Hazard Forecasting Center, National Marine Environmental Forecasting Center, Beijing, 100081, China
  • 7Polar Meteorology and Climatology, Finnish Meteorological Institute, Helsinki, PO Box 33 FIN-00931, Finland

Abstract. The satellite observations unveiled that the July sea ice extent of the Arctic shrank to the lowest value in 2020 since 1979, with a major ice retreat in the Eurasian shelf seas including Kara, Laptev, and East Siberian Seas. Based on the ERA-5 reanalysis products, we explored the impacts of warm and moist air-mass transport on this extreme event. The results reveal that anomalously high energy and moisture converged into these regions in the spring months (April to June) of 2020, leading to a burst of high moisture content and warming within the atmospheric column. The convergence is accompanied by local enhanced downward longwave radiation and turbulent fluxes, which is favorable for initiating an early melt onset in the areas with severe ice loss. Once the melt begins, solar radiation played a decisive role in leading to further sea ice depletion due to ice-albedo positive feedback. The typical trajectories of the synoptic cyclones that occurred on the Eurasian side in spring 2020 agree well with the path of atmospheric flow. Assessments suggest that variations in characteristics of the spring cyclones are conducive to the severe melt of sea ice. We argue that large-scale atmospheric circulation and synoptic cyclones act in concert to trigger the exceptional poleward transport of total energy and moisture from April to June to cause this new record minimum of sea ice extent in the following July.

Yu Liang et al.

Status: open (until 23 Sep 2021)

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  • RC1: 'Comment on tc-2021-159', Anonymous Referee #1, 30 Aug 2021 reply

Yu Liang et al.

Yu Liang et al.

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Short summary
A record minimum July SIE was observed in 2020 since 1979. Our results reveal that anomalously high advection of energy and water vapor prevailed during spring (April–June) in 2020 over regions noticeable sea ice retreat. The large-scale atmospheric circulation and cyclones act in concert to trigger the exceptionally warm and moist flow. The great convergence of the transport changed the atmospheric characteristics and the surface energy budget, thus caused a severe sea ice melt.