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Precipitation changes in a GCM resulting from the indirect effects of anthropogenic aerosols
Author(s) -
Rotstayn Leon D.,
Ryan Brian F.,
Penner Joyce E.
Publication year - 2000
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 - 10.1029/2000gl011737
Subject(s) - northern hemisphere , environmental science , precipitation , gcm transcription factors , climatology , atmospheric sciences , southern hemisphere , aerosol , climate change , general circulation model , meteorology , geology , oceanography , physics
An atmospheric GCM coupled to a mixed‐layer ocean model is used to study changes in rainfall due to the indirect effects of anthropogenic aerosols. The model includes treatments of both the first and second indirect effects. The most striking feature of the equilibrium rainfall response to the indirect effects of anthropogenic aerosols is a southward shift of the equatorial rainfall. We hypothesize that this is caused by a hemispheric asymmetry in the cooling of the sea surface. This is supported by another pair of experiments, in which the model is run with prescribed present‐day SSTs. In one experiment the standard model is used, and in the other the SSTs in the Northern Hemisphere are increased by 1 K in the calculation of the surface fluxes, to mimic the effect of a return to pre‐industrial conditions. Compared to the run with increased NH SST, the standard run shows a southward shift of equatorial rainfall, similar to that obtained as a response to anthropogenic aerosols.