Speaker
Description
Following the TropiScat campaign initiated during the early stages of the Biomass mission preparation activities, the AfriScat campaign has been also supported by ESA in order to consolidate the previous findings, considering two independent cases of dense tropical forests in French Guiana and Ghana respectively. Among these findings, the characteristics of the temporal decorrelation patterns at P-band are not only a key topic for the design of Biomass repeat passes, but also contribute to a better understanding of the backscatter temporal changes in relation to environmental conditions.
In this paper, we will first focus on a statistical analysis dedicated to assess the expected temporal decorrelation according to various mission scenarios, including the Biomass tomographic and PolInSAR phases. Consistently with TropiScat results, we show that seasonal effects strongly impact the coherence decrease as a function of temporal baseline, with a constant decrease during the dry season while the rainy season is characterized by a drop during the first days before reaching a plateau which eventually provides after about 30 days higher coherences than for the dry season.
In order to better understand these results and their extension to ground and volume layers separated by tomography processing, a quantitative analysis has been performed using EM simulations based on the MIPERS model, from which several hypothesis can be tested. Among them, the possible effects of wind motion, vegetation growth, leaf flushing, vegetation water content and soil moisture variations have been tested, given a parametrization based on ranges derived from additional in situ measurements that could be acquired during experiments dedicated to diurnal cycles, on top of the 3D tree architecture derived from TLS data.
Finally, this study is extended with L-band results, which are not only interesting for the design of future L-band SAR missions but also to strengthen the simulations results with additional observables and the same input parametrization. Further results dedicated to prospects of synergies between P and L-bands observations will be also introduced in the frame of the upcoming Biomass and NiSAR missions.
