Towards detecting mowing of agricultural grasslands from multi-temporal COSMO-SkyMed data

This work investigates applicability of spaceborne repeat-pass interferometric SAR images for detecting mowing events on agricultural fields. Four pairs of one-day repeat-pass COSMO-SkyMed acquisitions were analysed and compared to in situ measurements of 11 agricultural grasslands to study the potential of X-band temporal interferometric coherence for detecting mowing events. Field works covered 11 test plots in Central Estonia with varying species composition and homogeneity. Temporal decorrelation due to changes in the grass height and wet biomass was analysed. A nonlinear relationship was observed between the wet biomass and temporal coherence, as well as between the grass height and the temporal coherence. Our results show that one-day temporal coherence decreases as the grass height and the wet biomass increases, until reaching a noise level at 25 cm and 400 g, respectively. The current study shows that detecting mowing event from multitemporal interferometric SAR images is a feasible technique and could be used for monitoring applications on the European level.