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Roles of Wet and Dry Components of Moist Isentropic Mass Circulation in Changing the Extratropical Surface Temperature in the Northern Hemispheric Winter
  • Ruxue Liang,
  • Yueyue Yu,
  • Chunhua Shi
Ruxue Liang
Nanjing University of Information Science & Technology
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Yueyue Yu
Nanjing University of Information Science & Technology

Corresponding Author:[email protected]

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Chunhua Shi
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This study separates the dry and wet components of the moist isentropic mass circulation (MIMC) on daily timescale and investigates their relationships with extratropical surface temperature changes in winter. Results derived from ERA5 reanalysis data (1979-2018) show that, the MIMC is composed of a poleward warm branch (WB) in upper layers, which is dominated by the wet component in mid-latitude troposphere but by the dry component to the rest, and an equatorward cold branch below, dominated by the dry component. The stronger wet component of WB in 50-70N (WB_W) is a better precursory indicator than the dry component (WB_D) for the Arctic surface warming in winter, because of its dominant role in modifying the downward longwave radiation via water vapor-related processes. The stronger WB_D is coupled with negative Arctic Oscillation and a stronger equatorward transport of colder air, thus a better precursor for the cold events in the mid-latitudes.