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

Sushant Das, Sagnik Dey, S. K. Dash, G. Giuliani, F. Solmon
<span title="2015-09-27">2015</span> <i title="American Geophysical Union (AGU)"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/6naqln7f7nbprcsdwzruaarcne" style="color: black;">Journal of Geophysical Research - Atmospheres</a> </i> &nbsp;
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
more &raquo; ... the monsoon circulation leading to enhanced precipitation over India. The intensity of precipitation and wind field at 850 hPa 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. The magnitude of response of atmospheric circulation to dust DRE (or DRE of any other aerosol species) based on modeling exercises depends on the magnitude of aerosol absorption simulated by the model DAS ET AL. DUST RADIATIVE FEEDBACK OVER INDIA 9642 Key Points: • Sensitivity of Indian summer monsoon intensity to dust SSA is examined • Absorbing dust over Arabian Peninsula enhances rainfall over India • Dust feedback leads to a vertical temperature dipole over the Gangetic Plain We choose the South Asia Coordinated Regional Downscaling Experiment domain for our model simulation, which covers all the major deserts and arid regions [Das et al., 2013 ] that can possibly act as sources for dust transported to the Indian subcontinent. The simulations have been carried out at 50 km grid resolution, and the initial and lateral boundary conditions are forced with 6-hourly ERA-interim 1.5°× 1.5°gridded reanalysis data. The sea surface temperature data are extracted from National Oceanic and Atmospheric Administration
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