Convective invigoration and lifecycle enhancement by Aerosols-Cloud Field Couple over the Tropical Region using the A-Train and ISCCP Satellites Datasets

The influence of aerosols on cloud and precipitation on climate scales has been suggested by some numerical simulations and observational studies. However, counter examples also exist and whether the claimed influence is significant in general on climate scale remains unclear, in part due lack of information related to cloud life cycle. To address this limitation, we use along-track NASA A-Train satellites data, modern era retrospective - analysis for research and applications, and International Satellite Cloud Climatology Project (ISCCP) deep convection tracking data to evaluate interaction between aerosol and mesoscale convective systems as a function of convective life cycle. We have estimated the influence of aerosol on cloud microphysics over the regions of South Asia (0-40N, 70-100E), the Congo (10N-10S; 10W-40E), and the Amazon (5N-15S; 40W-80W) during June 2006 to May2008, when all these datasets were available. Our results suggest a statistical significant correlation between an increase of cloud ice-to-liquid ratio associated with an increase of aerosols optical depth (AOD) over these three tropical continents during the two years analysis period (p<5%), especially during the growing and mature phases of the convective life cycle. During the growing phase of the convective systems, the vertical wind shear appears to have strongest influence on the cloud ice-to-liquid ratio than AOD, whereas during the mature phase, AOD appears to have comparable influence to the vertical wind shear. Numerical of the convective core and radius of the convective systems have less influence compared to the vertical wind shear and AOD. The ice water content of the convective anvils, measured by AURA Microwave Limb Sounder, are also positively correlated with the AOD, as well as with the related humidity at 850 hPa, during the growing and mature phases of the convective systems. Whereas during the decay phase of the convective system, the anvil ice water is negatively correlated with the ambient AOD. We also explore the relationship between the convective lifecycle, ambient AOD, vertical wind shear and relative humidity, as well as size of the convective systems. Ambient AOD does not appear to be correlated with the convective duration at any stage of their lifecycle. Convective life time appear to be dominated by the convective dynamic structure, such as the radius, the number of convective cores, convective fraction of the convective systems, and the ambient relative humidity and vertical wind shear. Our work demonstrates that a clear dependence of the convection-aerosol relationship on the convective life cycle, and the potential of more clear diagnosis of the aerosols influence on convective system, relative to other ambient and convective dynamic conditions.