Speaker
Description
Following the TropiScat and AfriScat experiments that took place in French Guiana and Ghana respectively between 2011 and 2017 in the framework of the preparation phase of BIOMASS mission, a new campaign TropiScat-2 has been set up since March 2018. This campaign, located in the experimental site of Paracou in French Guiana, has three major interrelated objectives: First, to extend the time series provided from previous TropiScat and AfriScat missions, mainly aiming at characterizing P-band temporal decorrelation, a key element for BIOMASS mission acquisition scenarios. Second, to investigate the possible synergies between BIOMASS and other sensors, such as SENTINEL1 that provides C band data acquired with a short revisit time. Finally, to deepen our understanding of the underlying physics, based on electromagnetic models requiring a detailed characterization of the environment, both in regard to the 3D geometry of the scatterers and their water content (dielectric constants).
This new campaign started by a feasibility study that allowed us to select different types of C-band antennas which were tested in March 2018 according to several configurations by adjusting the acquisition time and studying the coherence and intensity variability over many days. Preliminary results demonstrated an important effect of environmental conditions on the evolution of intensity and coherence. In particular, differences between day and night coherences were highlighted and explained by the convective motion of forest scatterers. Indeed, daytime coherence values obtained from repeat-acquisitions were already low after few seconds onwards, while we were able to obtain high coherence values (>0.6) up to several hours during night.
In addition to its multi-frequency features, this campaign is enriched with extensive in-situ measurements dedicated to the scene geometry by means of TLS (terrestrial laser scanning) acquisitions in addition to vegetation water content and soil moisture collected with new sensors. Future results from longer time series are expected to contribute to a cross-quantitative analysis among these in-situ measurements and multi-frequency data, while these preliminary results already provide a very interesting database for the development of future innovative C-band configurations.
