Seasonal Evaluation of Temperature Inversion over Cairo

The seasonal temperature inversion over Cairo, Egypt is evaluated during the period, September 2004 - September 2005. The area suffers from annually increased concentrations of suspended Particulate Matter (PM) associated with temperature inversion mainly during autumn and spring. The temperature inversion phenomenon was simulated using the 5^th generation of the Penn State NCAR mesoscale Model (MM5) improved by using accurate topology model and monthly averaged vegetation index. The results agree with ATOVS data and ground measurements of the PM10. The results conclude that the ground temperature inversion predominantly occurs during winter and spring, whereas the subsidence inversion role is observable in summer and autumn. Results show also that the inversion strength correlates to the PM10 measurements with a correlation coefficient of 0.87 during April and 0.79 during the simulation period. The co-existence of the GTI and STI over Cairo contributes to the observed high concentrations of the PM10 concentrations associated with the dark or black cloud episodes.