EVALUATION OF MODELS FOR ESTIMATION OF NET RADIATION FOR ALPINE SLOPING SURFACES

This paper describes and tests two models for estimating net radiation(or the radiation balance) on sloping surfaces of alpine environments.They are an empirical method based on the linear relationship between net radiation and global solar radiation and a flux-by-flux method involving the estimation of all the individual components of radiation budget independently.The results show that the empirical method is capable of predicting hourly net radiation on sloping surfaces to within about ±53 W m-2 under all sky conditions.During clear sky conditions,it could predict net radiation on slopes to within ±58 W m-2 or 16% of the measured values.The flux-by-flux method,although it did not perform as well as the empirical method,performed adequately and could give estimates of net radiation on slopes with root mean square error of less than 74 W m-2(20%) and a mean bias error of 27 W m-2(7%).