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Future Reductions in Polar Cold Air Mass and Cold Air Outbreaks Revealed From Isentropic Analysis
Author(s) -
Kanno Yuki,
Iwasaki Toshiki
Publication year - 2020
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 - 10.1029/2019gl086076
Subject(s) - environmental science , northern hemisphere , climatology , atmospheric sciences , extratropical cyclone , polar , middle latitudes , southern hemisphere , climate change , polar vortex , geology , troposphere , physics , oceanography , astronomy
This study quantifies future changes in the polar cold air mass (PCAM) below a threshold potential temperature of 280 K and its horizontal fluxes, which are an indicator for the intensity of cold air outbreaks, by analyzing the outputs from five climate models from the Fifth Coupled Model Intercomparison Project. Under the business‐as‐usual scenario, the multimodel means of the wintertime total hemispheric PCAM decrease by 37% in the Northern Hemisphere and by 34% in the Southern Hemisphere by the end of the 21st century. The midlatitude equatorward PCAM fluxes are projected to decrease significantly by around 2050. This is primarily due to the reduction of the PCAM and to a lesser extent due to the weakening of the extratropical meridional circulation. Finally, intermodel differences in the total hemispheric PCAM reduction are shown to be linearly related to the climate sensitivity to the global mean surface air temperature.