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Measuring spectral and spatial variations of UVA and UVB sky radiance
Author(s) -
Blumthaler M.,
Gröbner J.,
Huber M.,
Ambach W.
Publication year - 1996
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/96gl00248
Subject(s) - radiance , sky , zenith , diffuse sky radiation , solar zenith angle , radiative transfer , irradiance , sky brightness , remote sensing , environmental science , wavelength , aerosol , atmospheric radiative transfer codes , physics , atmospheric sciences , optics , scattering , meteorology , geology
Spectral sky radiance measurements have been obtained with a double monochromator using a 1.5° field of view under varying atmospheric conditions at selected sites in Europe. Spatial variations of the intensity of the sky radiance up to a factor of 10 are observed in the UVA, which decrease to a factor of 2 in the UVB. A distinct minimum of the sky radiance is observed, the location depends on the solar zenith angle but not on wavelength. It is located at scattering angles between 90° and 75° for solar zenith angles between 80° and 26°. A comparison between measurements of the sky radiance and radiative transfer calculations with an aerosol free atmosphere shows a strong dependence of UVB sky radiance on aerosol particles in contrast to UVA sky radiance and possibly a dependence on tropospheric ozone as well.