SOLAR ULTRA-VIOLET RADIATION CHANGES IN BAHRAIN

Long-term changes in solar ultra-violet radiation (UV) of wavelengths 295 to 385nm were measured in Bahrain. A tendency occurred towards a r eduction in UV intensity during the months of June, July, August and S eptember in each year. A calculation was made, and averaged, over seve ral years regarding the ratio of UV intensity for each month to the av erage global solar radiation for that month, on a horizontal surface, The average annual ratio was found to be 3.87% with a lowest value of 3.3% and a highest value of 4.35%. The measured UV intensity in Bahrai n was compared with those measured in countries in the Arabian Gulf, M iddle East, Northern Europe and in Alaska. An empirical equation has b een developed which estimates the monthly average UV intensity, with a maximum monthly percentage error of not more than 24%. This equation contains only three variables, namely humidity, sunshine fraction and extra-terrestrial solar radiation. (C) 1997 Elsevier Science Ltd.