Ground based ultraviolet (290-385 nm) and broadband solar radiation measurements in South-Eastern Spain

Presented here is the first analysis of hourly solar ultraviolet irradiance (290‐385 nm) and broadband global irradiance data, registered in a radiometric station located in the outskirts of Granada (37.18°N, 3.58°W, 660 m a.m.s.l.), an inland location in south-eastern Spain, during a 2-year period. According to the prevailing cloudless conditions, the results show that the highest UV radiation levels are received in June or July and the lowest in December. Hourly monthly means of the ratio UV to broadband solar radiation covers a range from a minimum of ca. 3% to a maximum of 5%. The higher values of this ratio are associated to cloudy situations. In this way for 1994, the lowest values of this ratio are encountered in December, and the highest value appears in May, associated with a higher frequency of cloudy days. The study of the ratio UV to global radiation hourly monthly means reveals a clear effect of the optical air mass and of the cloud cover. It is found that, the UV to broadband global radiation ratio increases with decreasing optical air mass and increasing cloud cover. © 1998 Royal Meteorological Society.