Dust Storm and Black Cloud Influence on Aerosol Optical Properties over Cairo and the Greater Delta Region, Egypt

We have analysed aerosol and cloud properties, obtained from moderate resolution imaging spectroradiometer (MODIS) data, over Cairo and the Greater Delta region during the spring months of March, April and May (MAM) and the autumn months of September, October and November (SON) in the years 2004, 2005 and 2006. During these two time periods, we have examined dust storms, dense haze and a smog-like phenomenon known, locally, as the ‘black cloud’. Our work is based on the aerosol optical depth (AOD), fine mode fraction (FMF) and cloud properties (cloud top temperature (CTT), cloud top pressure (CTP), atmospheric infrared sounder (AIRS) temperature profiles and water vapour column). High anomalous water vapour is detected, which we believe is as a result of pollution aerosols rather than dust and is hence acting as cloud condensation nuclei (CCN). The CTT shows increasing and decreasing trends, corresponding to the dust occurring at ,750–800 hpa and pollution episodes at .900 hpa, respectively as observed from the CTP. Temperature inversion conditions, as well as adverse weather conditions, contribute to the pollution observed by preventing pollutants from escaping to the higher atmosphere