Validation of Spectral and Broadband UV-B (290 - 325 nm) Irradiance for Canada

摘要: Stratospheric ozone depletion, as a result of increasing chlorofluorocarbons in the stratosphere, allows more UV-B irradiance (290 - 325 nm) to reach earth’s surface with possible detrimental biological effects. Be-cause there are few radiation stations, models useful tools for estimating irradiances where measurements not made. Estimates spectral and broadband from numerical model compared Brewer spectrophotometer at nine Canadian stations (Alert, Resolute Bay, Churchill, Edmonton, Regina, Winnipeg, Montreal, Halifax Toronto) 26 years data. The uses either discrete ordinate radiative transfer (DISORT) or delta-Eddington algorithms solve equation 49-layer, vertically inhomogeneous, plane-parallel atmosphere, cloud inserted between 2 3 km heights. Spectral calculations made 1 nm intervals. extraterrestrial irradiance, optical properties each atmospheric layer ozone, air mole-cules, aerosol albedo. A fixed depth 27 was satisfactory cal-culating cloudy sky all except arctic. Comparisons both daily totals monthly averaged irradiances. method is shown be unsuitable calculating under clear skies, wavelengths less than 305 absorption by high, large solar zenith angles. er-rors smaller overcast conditions. adequate total spec-tral (? conditions, although consistently overestimating ir-radiances. There good agreement averages mean bias error mainly 5% measured root square 25%, decreasing below 15% averages.