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Simultaneous spectroradiometry: A study of solar UV irradiance at two altitudes
Author(s) -
Blumthaler M.,
Webb A. R.,
Seckmeyer G.,
Bais A. F.,
Huber M.,
Mayer B.
Publication year - 1994
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 - 10.1029/94gl02786
Subject(s) - irradiance , solar zenith angle , altitude (triangle) , zenith , atmospheric sciences , albedo (alchemy) , environmental science , cloud cover , sunlight , solar irradiance , range (aeronautics) , ozone , aerosol , radiation , snow , remote sensing , meteorology , geology , physics , materials science , optics , cloud computing , art , geometry , mathematics , performance art , computer science , composite material , art history , operating system
Spectrally resolved measurements of solar ultraviolet (UV) radiation were made at adjacent mountain top and valley sites, vertically separated by 1 km. Data was collected over a period of 4 days in August 1993 providing simultaneously measured spectra for a range of zenith angles with both sites in direct sunlight and less than 2 octas of cloud cover. As there was no snow cover the local albedo was similar at both sites. Irradiances at the mountain site were 9% higher than the valley at 370 nm, increasing gradually to 11% at 320 nm. Across the UVB waveband the altitude effect increased dramatically to 24% at 300 nm. The magnitude of the altitude effect was independent of zenith angle, within the measurement accuracy, for the range z = 30°–70°. These measured differences between the mountain and valley station can be interpreted by model calculations using the corresponding differences in air pressure, column ozone and aerosol content.