Comparisons between UV Irradiances and Derived Total Ozone from the GUV-541 Radiometer with Measurements from Brewer and Dobson Spectrophotometers

摘要

The spectral UV irradiance was measured using the five channels of GUV-541 radiometer in Manchester (78 m altitude, 53.28° N, 2.14° W) since 1997. The derivation of total column ozone relies on the comparison of measured irradiance ratios, from the GUV, at two wavelengths in the UV region with synthetic ratios generated from the radiative transfer model for various ozone values and solar zenith angles. One of these wavelengths should be appreciably absorbed by ozone (305 nm) compared to the other one (340 nm). Two ratios (340/305 and 340/313) were adopted in this study. The average percentage difference between the observed (Brewer spectrophotometer) and derived total ozone was approximately 0.4% ±6% (2σ). The derived column ozone over Manchester shows good correlations with the measured one over Camborne and Lerwick from 1999 to 2002. The average seasonal column ozone and the seasonal UV index show a negative trend over the same period.