Ratio of UV to global broad band irradiation in Valencia, Spain

This paper presents the results of an analysis of 6 years of measurements o f UV and broad band irradiation values in Valencia, Spain. Hourly and daily integrated UV irradiance, I-TUV, measured by a TUVR Eppley radiometer, and global irradiance I-T from a Kipp-Zonen CM-11 pyranometer, were highly cor related, with I-TUV/I-T percentages varying from 2.9% to 3.5% for hourly va lues and from 2.9% to 3.4% for daily values. If a general linear relation I -TUV = mI(T) is considered, the correlation coefficient r is always greater than 0.96 for hourly values and 0.91 for daily values. However, the relati on between I-TUV/I-T and the clearness index k(T) is poorly correlated, alt hough improved results, with less dependence on a specific location, can be observed using the k(TUV) and k(T) clearness indices. For a general linear relation, k(TUV) = mk(T), the correlation coefficient r is always greater than 0.89 for hourly values and 0.86 for daily values. Copyright (C) 1999 R oyal Meteorological Society.