Abstract
Problem statement: The measurement of different components of direct solar radiation for this research has been carried out in Helwan, Egypt. Helwan (Latitude 29°52 N, Longitude 31°20 E). This is a considered as the largest polluted region in the world. The level of pollution in Helwan region is higher, compared to the international limit by about 7 or 10 times in industrial and populated region respectively. Approach: The daily variation for different components of solar radiation bands as global, direct (total, yellow, red and infrared) and diffuse solar radiation had been studied and discussed. The data measurements have been taken for nine years (1991-2000). Hourly data of solar irradiance on a horizontal plane had also been recorded simultaneously together with relative humidity and wind speed along with some traditional techniques for selecting the clear sky days of the period examined. Results: The results clearly showed seasonal dynamics in aerosol loading, type and perceptible water. Conclusion: Background levels of aerosols, which we defined as yellow color less than 0.10, had observed at almost all sites but varying frequencies.
Highlights
Man is altering the aerosol environment through land cover change, combustion of fossil fuels and the introduction of particulate and gas species to the atmosphere
The cloudiness is greater in Helwan reaches its maximum in winter while it's minimum value his attained in summer
The highest values occur in spring with the alternating hot and cold spells while the lowest values occur in the settled summer months
Summary
Man is altering the aerosol environment through land cover change, combustion of fossil fuels and the introduction of particulate and gas species to the atmosphere. Each perturbation has some impact on the local aerosol environment. Regardless of current conditions, the extent of local aerosol perturbations on a global scale is the subject of extensive ground level, airborne and satellite research (King et al, 1999; Pruppacher and Klett, 1978). The African turbidity network from 19801984 (D’Almeida, 1996), NASA’s 15 site Sahelian network (Eck et al, 1999) and the Niger network from 1986-1987 (Ben Mohamed et al, 1992) clearly, demonstrated the temporal and spatial variability and overall high aerosol loading in West Africa, during this decade of extreme Sahelian drought
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