The analysis of ultraviolet radiation in the Dead Sea basin, Israel

Abstract

The Dead Sea basin offers a unique site to study the attenuation of the ultraviolet (UV) radiation, as it is situated at the lowest point on Earth, about 400 m below sea level, and the air above the Dead Sea is characterized by a relatively high aerosol content due to the very high salt content of the Dead Sea. In view of its being an internationally recognized centre for climatotherapy, it is of interest to study both its UV intensity and attenuation as a function of wavelength relative to other sites. In order to provide a basis for intercomparison of the radiation intensity parameters measured at the Dead Sea, a second set of identical parameters were being measured simultaneously at a second site, located at a distance of ca. 65 km and to the west and situated above sea-level (Beer Sheva ata315 m a.s.l.). The ultraviolet radiation, both UV-B and UV-A, were monitored continuously at both sites using Solar Light Co. Inc. broad-band meters. In addition, sporadic measurements utilizing a narrow-band spectroradiometer were performed to ascertain the extent of site-specific spectral selectivity in the ultraviolet spectrum. The monthly average daily attenuation rates were found to vary from 710 2t o 7173 per cent 1000 m 71 and 733 to 787 per cent 1000 m 71 for UV-B and UV-A, respectively. The average monthly values for UV-B and UV-A are 7146 per cent 1000 m 71 and 754 per cent 1000 m 71 , respectively. These values are in the range of values reported previously for studies performed at high altitudes, e.g. in the Alps and the Andes. The relative attenuation in the ultraviolet range as a function of wavelength, i.e. site-specific spectral selectivity, decreases with increasing wavelength. Consequently, the spectral range most effective with regard to erythema undergoes the highest degree of attenuation. These findings are in accordance with radiation scatter theory # 1997 Royal Meteorological Society. Int. J. Climatol., 17, 1697‐1704