AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Multi-year Analysis of Aerosol Optical Depth and its Impact on Cloud Properties over a Coastal-urban City of South Africa as Retrieved from MODIS
A. JOSEPH ADESINA, Venkataraman Sivakumar, K. Raghavendra Kumar, University of Kwazulu-Natal, Durban, South Africa
Abstract Number: 11 Working Group: Aerosols, Clouds, and Climate
Abstract Clouds that are formed in a polluted environment tend to have smaller droplets which can bring about suppression of precipitation and temporal variation in cloud life time. Aerosols, a significant component of air pollution may lead to an increase in cloud optical thickness due to a combination of reduction in cloud droplet radius and increased water content. Its semi direct effect can inhibit cloud formation and evaporation of existing cloud so that aerosol – cloud interaction presents a major research area in atmospheric science. We have used the Terra Satellite onboard of the Moderate Resolution Imaging Spectroradiometer (MODIS) to investigate the spatial and temporal relationship between aerosol optical depth (AOD) and cloud parameters namely, water vapor (WV), cloud optical depth (COD), cloud fraction (CF), cloud effective radius (CER), cloud top temperature (CTT) and cloud top pressure (CTP). A seasonal variation of aerosol optical depth over Cape Town was found to be highest during the spring (September to November) and using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model we were able to trace the origins of the air masses. Our analysis of the temporal variation based on 5years (2008-2012) of dataset showed a strong positive correlation between AOD and WV. The correlation between AOD and COD, CF showed similar pattern of negative correlation from January to July and thereafter, positive for the remaining months of the year. The AOD and CER only showed positive correlation from March to July and then October to December. There is a noticeable positive correlation between AOD and CTT, CTP in all the months of the year, except from July to September. The co-variation of CTT and CTP may be due to large scale meteorological variation.