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Role of the Moist and Dry Components of Moist Isentropic Mass Circulation in Changing the Extratropical Surface Temperature in Winter
Author(s) -
Liang Ruxue,
Yu Yueyue,
Shi Chunhua,
Guan Zhaoyong
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl091587
Subject(s) - extratropical cyclone , climatology , atmospheric sciences , environmental science , troposphere , arctic , water vapor , isentropic process , warm front , latitude , meteorology , geology , oceanography , geography , physics , geodesy , thermodynamics
This study separates the dry and moist components of the moist isentropic mass circulation (MIMC) on a daily timescale and investigates their relationships with extratropical surface temperature changes in winter (November to February). Results from ERA5 reanalysis data set (1979–2018) show that the MIMC is composed of a poleward warm branch in the upper layers and an equatorward cold branch below. The warm branch (WB) is dominated by the moist component in the mid‐latitude troposphere, but by the dry component in other regions. The stronger moist component of WB at 50°N‐70°N (WB_M) is a better precursory indicator than the dry component (WB_D) for the Arctic surface warming as a result of its dominant role in modifying the downward longwave radiation via water‐vapor‐related processes. The stronger WB_D is coupled with a negative Arctic Oscillation and a stronger, longer‐lasting equatorward transport of colder air, therefore a better precursory indicator of mid‐latitude cold events.