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Significant Contribution of Stratospheric Water Vapor to the Poleward Expansion of the Hadley Circulation in Autumn Under Greenhouse Warming
Author(s) -
Xia Yan,
Wang Yuwei,
Huang Yi,
Hu Yongyun,
Bian Jianchun,
Zhao Chuanfeng,
Sun Cheng
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 - 10.1029/2021gl094008
Subject(s) - hadley cell , stratosphere , atmospheric sciences , environmental science , water vapor , climatology , greenhouse gas , polar vortex , atmospheric circulation , subtropics , general circulation model , climate change , geology , physics , meteorology , oceanography , fishery , biology
Widening of the Hadley circulation and associated poleward shifts of subtropical dry zones have drawn extensive studies in the past decade. It is found that the poleward expansion of the Hadley circulation has strong seasonality and peaks in autumn in both Hemispheres in response to quadrupling CO 2 . Here we find that the poleward expansion in autumn is closely related to the increase of stratospheric water vapor (SWV). The SWV increase radiatively cools the stratosphere especially in the polar lower stratosphere, which consequently leads to widening of the Hadley cell in autumn. The SWV effect is affirmed in a set of “SWV‐locking” experiments. It is found that the SWV increase leads to a poleward expansion of the Hadley circulation in autumn in both Hemispheres, which contributes about 30% of the total expansion due to quadrupling CO 2 in autumn.