Simultaneous spectroradiometry: A study of solar UV irradiance at two altitudes

authored by

M. Blumthaler, A. R. Webb, G. Seckmeyer, A. F. Bais, M. Huber, B. Mayer

Abstract

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.

Organisation(s)

Institute of Meteorology and Climatology

Type

Article

Journal

Geophysical research letters

Volume

21

Pages

2805-2808

No. of pages

4

ISSN

0094-8276

Publication date

1994

Publication status

Published

Peer reviewed

Yes

Electronic version(s)

https://doi.org/10.1029/94GL02786 (Access: Unknown)