http://www.agu.org/pubs/crossref/2012/2012JD017508.shtml
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 117, D13209, 20 PP., 2012 doi:10.1029/2012JD017508 Climate response of the South Asian monsoon system to anthropogenic aerosols Key Points - While BC can warm the atmosphere, we find anthropogenic aerosols mostly cool it - Local anthropogenic aerosols reduce the mean South Asian summer monsoon rainfall - Decreased aerosol emission from local fire sources increase rainfall over S Asia Dilip Ganguly Climate Physics, Pacific Northwest National Laboratory, Richland, Washington, USA Philip J. Rasch Climate Physics, Pacific Northwest National Laboratory, Richland, Washington, USA Hailong Wang Climate Physics, Pacific Northwest National Laboratory, Richland, Washington, USA Jin-Ho Yoon Climate Physics, Pacific Northwest National Laboratory, Richland, Washington, USA The equilibrium climate response to the total effects (direct, indirect and semi-direct effects) of aerosols arising from anthropogenic and biomass burning emissions on the South Asian summer monsoon system is studied using a coupled atmosphere-slab ocean model. Our results suggest that anthropogenic and biomass burning aerosols generally induce a reduction in mean summer monsoon precipitation over most parts of the Indian subcontinent, strongest along the western coastline of the Indian peninsula and eastern Nepal region, but modest increases also occur over the north western part of the subcontinent. While most of the noted reduction in precipitation is triggered by increased emissions of aerosols from anthropogenic activities, modest increases in the north west are mostly associated with decreases in local emissions of aerosols from forest fire and grass fire sources. Anthropogenic aerosols from outside Asia also contribute to the overall reduction in precipitation but the dominant contribution comes from aerosol sources within Asia. Local emissions play a more important role in the total rainfall response to anthropogenic aerosol sources during the early monsoon period, whereas both local as well as remote emissions of aerosols play almost equally important roles during the later part of the monsoon period. While precipitation responses are primarily driven by local aerosol forcing, regional surface temperature changes over the region are strongly influenced by anthropogenic aerosols from sources further away (non-local changes). Changes in local anthropogenic organic and black carbon emissions by as much as a factor of two (preserving their ratio) produce the same basic signatures in the model's summer monsoon temperature and precipitation responses. _______________ Ken Caldeira Carnegie Institution for Science Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 [email protected] http://dge.stanford.edu/labs/caldeiralab @kencaldeira *Our YouTube videos:* Climate change and the transition from coal to low-carbon electricity: Ken Caldeira <http://www.youtube.com/watch?v=a9LaYCbYCxo> Crop yields in a geoengineered climate: Dr. Julia Pongratz<http://www.youtube.com/watch?v=fhxzOUQVD38> More videos <http://www.youtube.com/user/CarnegieGlobEcology/videos> -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
