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UV‐B cloud optical properties for Canada
Author(s) -
Binyamin Jacqueline,
Davies John,
McArthur Bruce
Publication year - 2010
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.1966
Subject(s) - overcast , cloud albedo , optical depth , albedo (alchemy) , environmental science , effective radius , atmospheric sciences , irradiance , radiative transfer , single scattering albedo , aeronet , atmospheric radiative transfer codes , snow , arctic , latitude , solar zenith angle , cloud cover , middle latitudes , cloud top , climatology , aerosol , meteorology , cloud computing , physics , sky , satellite , geography , geology , astrophysics , geodesy , optics , art , galaxy , oceanography , computer science , operating system , art history , performance art , astronomy
Cloud optical properties play a highly significant role in the amount of UV‐B irradiance reaching the ground. Broadband values of UV‐B cloud optical properties are calculated for nine Canadian stations from 26 years of data. Cloud single scattering albedo ω c and asymmetry factor g c are computed from Mie theory for two values of equivalent droplet radius; 7 µm for arctic stations and 10 µm for midlatitude and subarctic stations. Overcast cloud optical depths τ c are estimated iteratively for a model cloud layer located between 2 and 3 km above the surface from hourly integrated spectral Brewer spectrophotometer measurements for snow‐free cases using either the discrete ordinate radiative transfer (DISORT) or the delta‐Eddington algorithms. Median τ c values calculated by both algorithms compare to within 3%. Median values are smaller for arctic stations (9–18) and between 26 and 38 for the rest. Both mean and median values are negatively correlated with latitude. Aerosol effect on τ c varies between 9 and 18% on average. Copyright © 2009 Royal Meteorological Society