6533b832fe1ef96bd129a278

RESEARCH PRODUCT

Comparison of global ultraviolet (290–385 nm) and global irradiation measured during the warm season in valencia, spain

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This paper studies data of ultraviolet (290–385 nm band) horizontal solar irradiation and global horizontal solar irradiation measured at Valencia (Spain) during the period March 1991 to September 1991. Analysis of error estimations and correlation coefficients show that the 10 minute, hourly, and daily values of ultraviolet (UV) and global irradiation are highly correlated. Improved figures and less dependence on location are achieved by defining a clearness index for the UV 290–385 nm band and relating it to the conventional whole-band clearness index. The novel clearness index obtained from Valencia data is approximately half of the conventional clearness index. Considering solar elevation as an additional parameter, the correlation coefficients increase to values in the 0.94 to 0.96 interval for solar elevations greater than 55°, both for hourly and 10-minute values.