A COMPARISON OF 2 RADIATION SCHEMES FOR CALCULATING ULTRAVIOLET-RADIATION

Citation
Pmde. Forster et Kp. Shine, A COMPARISON OF 2 RADIATION SCHEMES FOR CALCULATING ULTRAVIOLET-RADIATION, Quarterly Journal of the Royal Meteorological Society, 121(525), 1995, pp. 1113-1131
Citations number
36
Categorie Soggetti
Metereology & Atmospheric Sciences
ISSN journal
00359009
Volume
121
Issue
525
Year of publication
1995
Part
A
Pages
1113 - 1131
Database
ISI
SICI code
0035-9009(1995)121:525<1113:ACO2RS>2.0.ZU;2-E
Abstract
Increases in ultraviolet radiation (UV) caused by ozone depletion in t he stratosphere are expected to have physiological effects on plants a nd animals. Biologists require that the UV data have high wavelength r esolution to assess these effects adequately. Numerical simulations of scattering and absorption in the atmosphere provide a useful way of p redicting the UV irradiance reaching the ground and the results from s uch radiative transfer calculations are presented. Two different metho ds were used to calculate the diffuse irradiances: the Discrete Ordina te (D-O) method and the Delta-Eddington (D-E) approximation. Surface U V irradiances for a wide variety of atmospheric conditions, obtained w ith the D-O method were compared with those obtained using the D-E app roximation to assess how changes in tropospheric aerosol and cloud aff ect the accuracy of the D-E approximation. Stratospheric aerosol has b een shown to be capable of increasing the UV irradiances at the ground , the magnitude of these increases depending heavily on the absorption by ozone of multiply-scattered photons. The prediction of these incre ases by means of numerical models provides a good test of the accuracy of the radiative transfer approximations used. It is shown that the D -E approximation appears to be deficient for the prediction of surface irradiance at high spectral resolution, under certain circumstances.