A simplified physical model for assessing solar radiation over Brazil using GOES 8 visible imagery

Autor: Juan Carlos Ceballos, Marcus Jorge Bottino, Jaidete Monteiro de Souza
Rok vydání: 2004
Předmět:
Zdroj: Journal of Geophysical Research. 109
ISSN: 0148-0227
Popis: [1] Solar radiation assessment by satellite is constrained by physical limitations of imagery and by the accuracy of instantaneous local atmospheric parameters, suggesting that one should use simplified but physically consistent models for operational work. Such a model is presented for use with GOES 8 imagery applied to atmospheres with low aerosol optical depth. Fundamental satellite-derived parameters are reflectance and cloud cover. A classification method applied to a set of images shows that reflectance, usually defined as upper-threshold Rmax in algorithms assessing cloud cover, would amount ∼0.465, corresponding to the transition between a cumuliform and a stratiform cloud field. Ozone absorption is limited to the stratosphere. The model considers two spectral broadband intervals for tropospheric radiative transfer: ultraviolet and visible intervals are essentially nonabsorbing and can be processed as a single interval, while near-infrared intervals have negligible atmospheric scattering and very low cloud transmittance. Typical values of CO2 and O3 content and of precipitable water are considered. A comparison of daily values of modeled mean irradiance with data of three sites (in rural, urban industrial, and urban coastal environments), September–October 2002, exhibits a bias of +5 W m−2 and a standard deviation of ∼15 W m−2 (0.4 and 1.3 MJ m−2 for daily irradiation). A comparison with monthly means from about 80 automatic weather stations (covering a large area throughout the Brazilian territory) still shows a bias generally within ±10 W m−2 and a low standard deviation (
Databáze: OpenAIRE
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