Agricultural monitoring using envisat alternating polarization SAR images

In agricultural remote sensing, applied images should be acquired frequently enough in order to monitor important crop growth stages. Thanks to the cloud penetrating and flexible swath-positioning capabilities of space-borne SAR at present, images can be acquired even at the interval of few days during a growing season. In this study, dual-polarization (VV/VH) Envisat SAR images with high a temporal resolution were used in association with limited ancillary data to monitor crop growth and to classify crop species. It was noticed that the high temporal resolution enabled nearly continuous monitoring, but it also caused problems because of the varying incidence angles. Moreover, to carry outfield surveys rapidly enough for research purposes was observed as a problem. An R-2 of 0.55 was obtained for estimating the crop growth, when average crop height in parcels was used to describe the amount of biomass. An overall accuracy of 74.7 percent was achieved for crop species classification. Envisat VH polarization appeared to be useful in the estimation, even though, the noise equivalent sigma(0) was too high to detect early crop growth. Field-based averaging was required, thus, for example for precision farming purposes a better spatial resolution would be needed to detect biomass variations within parcels.