Crop monitoring using SAR and optical data

Under the framework of the European Union (EU) programme for Monitoring Agriculture by Remote Sensing (MARS), there is a major action devoted to the rapid estimation of crop surface coverage (and hence potential yield levels) over the entire European Union.
This is based on the analysis of SPOT and Landsat optical data together with ERS-1 SAR imagery over 60 test sites and is implemented using computer aided visual interpretation of the images. The programme is conducted by the Joint Research Centre with the support of a limited number of European contracting companies.

At present, optical imagery is acquired at least four times growing season and analysed using computer aided photo interpretation. The results are used to generate forecasts which are then sent to DG VI (agriculture) at the EU headquarters in Brussels.
Due to the nature of EU agricultural policies and the nature of agricultural subsidies in particular, early crop acreage estimates are an important tool in the effective management and administration of the EU. For example, such information allows the planning of distribution resources, subsidy levels and storage facilities.

The figure shows a comparison of SPOT versus ERS-1 images. Various crop types in the agricultural region south of Seville are visible in each image. Information obtained from each image is complementary.
Due to unfavourable weather conditions in northern Europe, image acquisition by optical sensors can be extremely difficult. In 1993 for example, no data could be acquired for an Irish test site. The all weather capability of the ERS SAR allows year round data acquisition however.
SAR PRI data are combined to form multi-temporal images. A classification analysis is then performed in order to identify the various crop species of interest and the surface cover of particular crop species is calculated.

Two examples are provided to show various classifications for selected test sites throughout Europe. Different crop species can be identified in the various sites.
Example N 1
Example N 2

(Joint research centre, Ispra, Italy)

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry