Dust aerosol feedback on the Indian summer monsoon: Sensitivity to absorption property

We examine the sensitivity of dust radiative feedback to the dust absorption property during the Indian summer monsoon (June-September) season from 2005 to 2010 using the Regional Climate Model version 4.1. The dust direct radiative forcing at top of atmosphere switches from cooling to warming for absorbing dust over the Indian subcontinent. The dust-induced low pressure anomaly plays a crucial role in building up large-scale convergence particularly over the Arabian Peninsula, which strengthens the monsoon circulation leading to enhanced precipitation over India. The intensity of precipitation and wind field at 850hPa increases over India by considering more absorbing dust. Air temperature and cloud fraction change by 20-50% in the lower to middle troposphere as a result of dynamic response due to modification in dust absorptive characteristics. Our results demonstrate that the response of monsoon circulation to dust radiative feedback is highly sensitive to dust absorption; and hence, it should be accurately represented in the models for improved simulation of monsoon precipitation. The results have important implications in case of break-to-active transition within the Indian summer monsoon season.