Fast and Slow Responses of the South Asian Monsoon System to Anthropogenic Aerosols

TitleFast and Slow Responses of the South Asian Monsoon System to Anthropogenic Aerosols
Publication TypeJournal Article
Year of Publication2012
JournalGeophysical Research Letter
Number18
Date Published09/2012
Abstract / Summary

Using a global climate model with fully predictive aerosol life cycle, we investigate the fast and slow responses of the South Asian monsoon system to anthropogenic aerosol forcing. Our results show that the feedbacks associated with sea surface temperature (SST) change caused by aerosols play a more important role than the aerosol's direct impact on radiation, clouds and land surface (rapid adjustments) in shaping the total equilibrium climate response of the monsoon system to aerosol forcing. Inhomogeneous SST cooling caused by anthropogenic aerosols eventually reduces the meridional tropospheric temperature gradient and the easterly shear of zonal winds over the region, slowing down the local Hadley cell circulation, decreasing the northward moisture transport, and causing a reduction in precipitation over South Asia. Although total responses in precipitation are closer to the slow responses in general, the fast component dominates over land areas north of 25°N. Our results also show an east-west asymmetry in the fast responses to anthropogenic aerosols causing increases in precipitation west of 80°E but decreases east of it.

URLhttp://onlinelibrary.wiley.com/doi/10.1029/2012GL053043/abstract
DOI10.1029/2012GL053043
Journal: Geophysical Research Letter
Year of Publication: 2012
Number: 18
Date Published: 09/2012

Using a global climate model with fully predictive aerosol life cycle, we investigate the fast and slow responses of the South Asian monsoon system to anthropogenic aerosol forcing. Our results show that the feedbacks associated with sea surface temperature (SST) change caused by aerosols play a more important role than the aerosol's direct impact on radiation, clouds and land surface (rapid adjustments) in shaping the total equilibrium climate response of the monsoon system to aerosol forcing. Inhomogeneous SST cooling caused by anthropogenic aerosols eventually reduces the meridional tropospheric temperature gradient and the easterly shear of zonal winds over the region, slowing down the local Hadley cell circulation, decreasing the northward moisture transport, and causing a reduction in precipitation over South Asia. Although total responses in precipitation are closer to the slow responses in general, the fast component dominates over land areas north of 25°N. Our results also show an east-west asymmetry in the fast responses to anthropogenic aerosols causing increases in precipitation west of 80°E but decreases east of it.

DOI: 10.1029/2012GL053043
Citation:
2012.  "Fast and Slow Responses of the South Asian Monsoon System to Anthropogenic Aerosols."  Geophysical Research Letter.  https://doi.org/10.1029/2012GL053043.