Climate affected by dust aerosol over arid region of Makkah, Saudi Arabia

Aerosols play an important role in the global climate balance, and therefore they could be important in climate change. Natural variations of aerosols, especially due to dust storm are recognized as a significant climate forcing, that is, a factor that alters the Earth's radiation balance and thus tends to cause a global temperature change. Aerosol optical depth, tau(lambda) is the most comprehensive variable to characterize aerosol due to atmospheric pollution. The aerosol optical properties in Makkah observed during dust period (March-may) from 2006 to 2009 had been presented in this study. Aerosol optical depths at all wavelengths showed a sharp increase during major dust outbreak in spring when compared with the average for the season. For example at Makkah, aerosol optical depths increase from the spring average value of 0.43+/-0.02 at 550 nm to values >0.70 during major dust event days in 2006. These tend to increasingly of temperature during this period as results of absorbing aerosol effect. In this paper, we used AOD data from Terra MODIS to evaluate the trend of dust aerosol events in Makkah throughout 4 years dataset with supported data of subtype of aerosol and air temperature from CALIPSO and MERRA respectively. The higher values of AOD are corresponding to the low visibility due to presents of high concentration of dust.