Impact of anthropogenic aerosols on Indian summer monsoon

• Published in: Geophysical research letters Vol. 36; no. 21; pp. L21704 - n/a
• Main Authors: Wang, Chien, Kim, Dongchul, Ekman, Annica M. L., Barth, Mary C., Rasch, Phillip J.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.11.2009; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: Absorption; aerosol; AEROSOLS; ARABIAN SEA; Atmospheric aerosols; Atmospheric sciences; black carbon aerosols; BOUNDARY LAYERS; climate; Climate change; CONVECTION; dynamics; Earth; Earth sciences; Earth, ocean, space; Exact sciences and technology; GEOSCIENCES; Geovetenskap; HEATING; Hydrology; INDIA; Indian; Marine; MONSOONS; NATURAL SCIENCES; NATURVETENSKAP; numerical model; origin; Perturbation methods; PRECIPITATION; SCATTERING; Seasons; Summer; Indian Ocean; Asia; China; Qinghai-Xizang Plateau; Arabian Sea; Far East; India; China, People's Rep., Xizang, Tibetan Plateau; ISW, Arabian Sea; ISW, India; convection; atmospheric precipitation; strength; aerosols; Atmospheric boundary layer; warming; Climate models; clouds; Perturbation; slopes; Summer monsoon; energy
• ISSN: 0094-8276; 1944-8007; 1944-8007
• DOI: 10.1029/2009GL040114

Using an interactive aerosol‐climate model we find that absorbing anthropogenic aerosols, whether coexisting with scattering aerosols or not, can significantly affect the Indian summer monsoon system. We also show that the influence is reflected in a perturbation to the moist static energy in the sub‐cloud layer, initiated as a heating by absorbing aerosols to the planetary boundary layer. The perturbation appears mostly over land, extending from just north of the Arabian Sea to northern India along the southern slope of the Tibetan Plateau. As a result, during the summer monsoon season, modeled convective precipitation experiences a clear northward shift, coincidently in general agreement with observed monsoon precipitation changes in recent decades particularly during the onset season. We demonstrate that the sub‐cloud layer moist static energy is a useful quantity for determining the impact of aerosols on the northward extent and to a certain degree the strength of monsoon convection.