Aerosol-mediated changes in cloud radiative forcing from satellite and ground observations for deep convective clouds

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Wednesday, 5 February 2014
Hall C3 (The Georgia World Congress Center )
Zhanqing Li, Univ. of Maryland, College Park, MD; and J. Peng and H. Yan

For mixed-phase deep convective clouds, aerosol's invigoration effect is a dominant mechanism governing the interactions between aerosols and clouds due partially to the release of latent heat as cloud droplets convert into ice crystals. Such an effect can impede upon cloud radiative forcing significantly by altering cloud microphysics, cloud height and cloud extent, but little is known on the magnitude or even the sign for each of the components. Using a large ensemble of data from satellite and surface measurements, we are trying to sort out and estimate the effects. Using the rich A-Train satellite data, an algorithm to automatically identify all deep clouds was developed and the relationship between these clouds and aerosol loading is examined. Preliminary results show that there is a significant enhancement in both shortwave CRF and longwave CRF with increasing aerosol index (AI) over oceans and aerosol optical depth (AOD) over land for mixed-phase clouds; no significant change was seen for liquid clouds. Cloud-top height, cloud thickness and cloud ice processing appear to be positively correlated with AI/AOD, which indicates that the correlation between CRF and aerosol loading may be explained via microphysical and invigoration effects. Considering the inherent limitation, we also employ the ARM ground-based data to independently estimate these aerosol-mediated cloud radiative forcing.