IMPROVING THE ESTIMATION OF GLOBAL SOLAR-RADIATION ACROSS CANADA

Methods used to estimate global solar radiation at the Earth's surface from sunshine duration and other meteorological parameters are examined at six sites across Canada. Methods based only on sunshine duration are accurate enough on fitted data, but regression coefficients a and b showed large variations on a station-to-station basis and on a seasonal basis. As a consequence of which they can generate large errors of estimation when applied to independent data through all the country. A method using monthly mean fraction bright sunshine to account for temporal variations and a method using latitudes to account for spatial variations in a and b coefficients, are found not to provide any significant improvement on an independent set of data. Equations which include daily rainfall and minimum temperature provide the best estimate for localities where global solar radiation data are not available. © 1990.