Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Astronmy and Meteorology

Background: The UV Index (UVI) has been introduced as a useful tool to inform the public about the potentially harmful effects of UV radiation. For the general public it is usually given as an integer number. UV intensity is described in terms of ranges running from low values (less than 2), moderate (3{u2013}5), high (6{u2013}7), very high (8{u2013}10) and extreme (11+). Objective: This work concentrates on three aspects: first, Study the degree of accuracy of OMI to measure UVI over Egypt. Second, produce an empirical equation to calculate UVI with the aid of global radiation and solar zenith angle. Third, Study the effect of climate change on UVI during 2020 to 2030. Subjects and Methods: provides firstly description of the studied locations (Mediterranean region, Urban, Tropical region, and Red Sea region). Then, description of satellite ultraviolet index of OMI/AURA data, Ground-based measurement UV-B solar radiation, Ground-based measurement surface solar radiation, MPI{u2010}ESM globsl model structure, and regional climate model structure. Finally, discussed the data analysis (model for predicting UVI, model goodness of fit statistics and comparison methods).Results: UV index measurements from the OMI/AURA found that UVIsat overestimates UVIgrd at urban and tropical sites with MBE ranged from 0.5 at Aswan to 0.7 at Cairo and underestimates it at costal site with MBE equals -0.25 at Matruh. UVIest underestimates UVIgrd at Matruh and Aswan with MBE equal to -0.52 and -0.2, and MAPE of 17.4 and 10.0% respectively. Whereas UVIest overestimates it at Cairo with MBE equal to 0.32 and MAPE equals 11.0%. UVIest underestimates UVIsat at all stations with to -0.47, -0.43, -1.13, and -0.32 at Matruh, Cairo, Aswan, and Hurghada respectively and MAPE ranged from 7.4 to 14.9%

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