Dust Induced Radiative effect on Marine Clouds during Monsoon Breaks
During monsoon breaks, the results depicted maximum aerosol optical depth (AOD) above 10 º N and varied from 0.3 to 1.5. The vertical profile of dust backscatter coefficient (DBC) over AS showed an elevated layer between 2 to 4.5 km having maximum probability of occurrence around 3.5 – 4 km. The heating rate profile computed from SBDART radiative transfer model by using the CALIPSO derived vertical profile of dust AOD, showed a maximum of 8 K/Day, where DBC maximum is observed. The vertical distribution of dust aerosols is consistent with the direction of air-mass back trajectories indicating that the elevated layer is a result of intrusion of dry desert air from north western countries.
Short wave flux (SWF) at top of the atmosphere (TOA) is found to be less with dust as compared to without dust events, also the difference is more in case of cold clouds as compared to warm clouds. At the same time long wave flux (LWF) at TOA is more for clouds present in dusty atmosphere. In case of cloud micro and macrophysical parameters also significant differences are observed with and without dust. The percentage difference is observed to be much higher for cold clouds as compared to warm clouds. The results also indicate that semi-direct effect is more pronounced in cold clouds as compared to warm clouds. Such changes could affect the dynamical as well as circulation patterns in the immediate meso-scale environment during monsoon breaks.