SOLAR RADIATION IN MCYFS
Solar radiation in MCYFS
Among the required meteorological input variables to crop growth models solar radiation is the most difficult parameter to obtain due to the limited number of weather stations that measure this variable. In most European countries, the network of solar radiation measuring stations is too sparse for a reliable interpolation of direct measurements. The MARS Crop Yield Forecasting System employs empirical solar radiation models, which estimate solar radiation based on more commonly measured meteorological variables. For each weather station, the measurement of solar radiation model used depends on the parameters measured at that station. If solar radiation is directly measured, this measurement is used. Otherwise if sunshine duration estimate is available, global radiation is modelled with the Ångström-Prescott model (Ångström, 1924; Prescott, 1940). If cloud cover, minimum and maximum temperature are available, global radiation is calculated using the Supit-Van Kappel model (Supit and Van Kappel, 1998). If only minimum and maximum temperatures are available then global radiation is derived using the Hargreaves model (Hargreaves et al., 1985). More details about solar radiation models used in MCYFS can be found in CGMS version 9.2.
Solar radiation estimates from satellite observations
The down-welling surface shortwave radiation flux (DSSF) product is derived from the Meteosat Second Generation satellite data by the the
Land Surface Analysis Satellite Applications Facility (LSA SAF) and processed by Flemish Institute for Technological Research (VITO) on behalf of the JRC-MARS.
The evaluation of the down-welling surface shortwave radiation flux (DSSF) product shows a good agreement with measured solar radiation. The evaluation of the DSSF product shows that it is a major improvement over the current approach for deriving global radiation implemented in MCYFS.
Meteosat First Generation
The solar surface irradiance (SIS) dataset delivered by Satellite Application Facility on Climate Monitoring (CM SAF) product was derived from the Meteosat First Generation satellite imageries. The dataset includes solar radiation estimates from 1983 to 2005. The preliminary analysis shows that SIS dataset could be used to extend the solar radiation time series in MCYFS for the years before 2005.
The specific objectives of the project