European-scale Evaluation of the Capacity of Satellite Remote Sensing Indicators to Estimate Regional Crop Yields
Lopez-Lozano, Raul; Duveiller, Gregory; Seguini, Lorenzo; Garcia-Condado, Sara; Baruth, Bettina
European Commission, Joint Research Centre, ITALY

Operational activities in crop yield forecasting require a multidisciplinary approach to correctly interpret the effects of weather on crop growth and yield. Such approach typically relies onlocal and/or remote observations of weather and vegetation, and can also include simulation tools to model crop growth.The synoptic coverage and temporal revisit frequency of satellite remote sensing observations have proved to be a precious tool for agriculture monitoring. The necessary trade-off between geographical coverage and information detail (spatial, temporal and spectral) often results in mixed pixels, containing a mixture of signals from various different land uses. However, in various situations, this mixed signal may be sufficient to successfully integrate remote sensing in a crop growth monitoring system. This study is based on the20 years of experience in crop yield forecasting of the Monitoring Agricultural ResourceS (MARS) Unit of the European Commission Joint Research Centre, and presents a systematic evaluation of how remote sensing indicators relate to official crop yield time series for wheat and barley over Europe at the NUTS2/NUTS3 administrative regions level. These indicators consist of cumulated values of FAPAR and NDVI products at 1km spatial resolution that are currently being operationally used in the MARS Crop Yield Forecasting System (MCYFS) and which are compatible with future services that will be provided by the European Copernicus Programme. Major attention is paid to the interpretation of climate and management practices effects in the link between biomass observation from optical satellite imagery and yields, outlining the conditions where remote sensing approaches can help explaining yield seasonal variability, but also the main limitations in operational long-term activities. By addressing the regional scale (NUTS2/NUTS3 administrative regions), this study also allows the exploration of aggregation effects that can occur when trying to provide yield estimations for large countries.