Statistical relationships between solar UVB and UVA radiation and global radiation measurements at two sites in Israel

Abstract

Statistical relationships between the hourly radiation intensity values of both ultraviolet-B (UVB) and ultraviolet-A (UVA), and of the corresponding global radiation at two sites in Israel, the Dead Sea and Beer Sheva, are presented using radiation data measured from January 1995 to January 1999. It was determined, based upon the square of the correlation coefficient (r 2 ), that in the case of the UVB, a quadratic equation provided a better fit of the database, whereas in the case of UVA, a linear equation was sufficient, i.e. no significant improvement in r 2 was obtained using a quadratic equation. Each monthly empirical equation was tested by utilizing measurements from a single month of independent observations. The accuracy of the individual equations was determined by calculating the mean bias error (MBE), the root mean square error (RSME) and the percent coefficient of variation (CV). The results of this statistical analysis showed that, at both sites, the UVA relationships were characterized by a CV of B10%, with the exception of a single month. In the case of the UVB correlations, the CV values exceeded 10% for more than 75% of the year, both at the Dead Sea and at Beer Sheva. CV values of \20% were observed for more than a third of the individual months at both the Dead Sea and Beer Sheva. Monthly and seasonal relationships from one site were then tested by applying them to the second site. In both cases, the relationships between both UVA and UVB and global radiation were found to be site-specific. On the basis of this statistical analysis, the UVA relationships were found to be far superior predictors than the corresponding UVB ones. In fact, the UVB relationships have limited applicability for predicting UVB from the corresponding global solar radiation intensity.

Relationship between the NO<sub>2</sub> photolysis frequency and the solar global irradiance

“…1 and 2a, b represents an almost vanishing j (NO 2 )↓ increase at small SZAs, while G is still benefiting from the increase of the cosine weighting factor. Correlating j (NO 2 ) with the UV irradiance also results in a curvature with increasingly higher values of the UV irradiance (Madronich, 1987a) and consistently, the relationship between UV-A irradiance and G can be described by a near-linear dependency (Canada et al, 2003;Jacovides et al, 2006;Kudish and Evseev, 2000;Ogunjobi and Kim, 2004). However, some previous studies also found near-linear relationships between j (NO 2 ) and G (e.g., Bahe et al, 1980;Brauers and Hofzumahaus, 1992;Schere and Demerjian, 1978;Wratt et al, 1992).…”

Study of erythemal, UV (A + B) and global solar radiation in Valencia (Spain)

“…Several authors have presented models for estimating the UVB irradiance from data on UVA or global irradiance. Kudish and Evseenv (2000) show a statistical 699 relationships between the UVB and UVA irradiances and the global irradiance at two sites in Israel. They indicate that the calculation of the UVA irradiance from the global irradiance behaves better than the calculation of the UVB irradiance from the Global because of the dominant role that ozone plays in the attenuation of the UVB and its practically negligible effect on the attenuation of the UVA and global irradiances.…”

Solar global UV (280–380nm) radiation and its relationship with solar global radiation measured on the island of Cyprus

“…Koronakis et al [22] reported an annual mean value of 4.1% over polluted Athens, Greece, whereas Kudish and Evseev [23], using UV-A measurements, found percent ratio values varying between 4.35% and 5.19% in the Dead Sea basin, Israel. However, the reported range of correlations suggests the desirability of local calibration to account for specific climatic conditions.…”