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

Meteosat Second Generation

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

  • To evaluate the solar radiation product DSSF (down-welling surface short-wave radiation flux) delivered by the Land Surface Analysis Satellite Applications Facility (LSA SAF) based on the Meteosat Second Generation imageries (since 2005). [published in Roerink et. al, 2012]
  • To evaluate the solar radiation dataset SIS (Solar surface irradiance) delivered by Satellite Application Facility on Climate Monitoring (CM SAF) based on Meteosat First Generation imageries (1983-2005).
  • To calibrate solar radiation models (Ångström -Prescott, Supit-Van Kappel, and Hargreaves) used in the MARS Crop Yield Forecasting System using satellite-based DSSF data as a reference.
  • To estimate of the error in solar radiation estimation caused by the interpolation of the model coefficients.
  • To evaluate the impact of different solar radiation data sources on the modelled crop growth parameters.

The project was conducted between 2010 and 2013.

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