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Origins of climate model discrepancies in atmospheric shortwave absorption and global precipitation changes
Author(s) -
Fildier Benjamin,
Collins William D.
Publication year - 2015
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 - 10.1002/2015gl065931
Subject(s) - shortwave , longwave , shortwave radiation , environmental science , precipitation , atmospheric sciences , climate model , radiative transfer , climatology , climate change , sky , meteorology , physics , radiation , geology , oceanography , quantum mechanics
Projected increases in mean precipitation are constrained by the atmospheric energy budget through radiative‐convective equilibrium. However, significant differences persist between climate models on the rate of increase in precipitation per unit warming, mostly arising from the clear‐sky radiative response. While the intermodel spread in clear‐sky longwave cooling has been explained by climate feedbacks, the sources of spread in clear‐sky shortwave heating are still unclear. This article focuses on the latter. Since water vapor contributes most of the atmospheric shortwave absorption, both intermodel differences in its spatial distribution and in radiative transfer parameterizations are plausible hypotheses for the spread. This work reestablishes the primary contribution from water vapor relative to other shortwave‐absorbing species and evaluates the validity of both hypotheses. It is found that the intermodel spread in shortwave absorption change most likely originates from the radiation schemes, possibly because of simplifications induced by their low spectral resolutions.