The TropiSAR Airborne Campaign in French Guiana: Objectives, Description, and Observed Temporal Behavior of the Backscatter Signal

Abstract

The TropiSAR campaign has been conducted in August 2009 in French Guiana with the ONERA airborne radar system SETHI. The main objective of this campaign was to collect data to support the Phase A of the 7th Earth Explorer candidate mission, BIOMASS. Several specific questions needed to be addressed to consolidate the mission concept following the Phase 0 studies, and the data collection strategy was constructed accordingly. More specifically, a tropical forest data set was required in order to provide test data for the evaluation of the foreseen inversion algorithms and data products. The paper provides a description of the resulting data set which is now available through the European Space Agency website under the airborne campaign link. First results from the TropiSAR database analysis are presented with two in-depth analyses about both the temporal radiometric variation and temporal coherence at P-band. The temporal variations of the backscatter values are less than 0.5 dB throughout the campaign, and the coherence values are observed to stay high even after 22 days. These results are essential for the BIOMASS mission. The observed temporal stability of the backscatter is a good indicator of the expected robustness of the biomass estimation in tropical forests, from cross-polarized backscatter values as regarding environmental changes such as soil moisture. The high temporal coherence observed after a 22-day period is a prerequisite for SAR Polarimetric Interferometry and Tomographic applications in a single satellite configuration. The conclusion then summarizes the paper and identifies the next steps in the analysis.

Analysis of PolInSAR precision for forest and ground parameters estimation in tropical context

“…The TropiSAR campaign was conducted in French Guiana in the summer 2009 [1] in the framework of the Phase A studies pertaining to the BIOMASS mission, one of the three for Earth Explorer candidates with the SETHI radar operated by ONERA. In this paper we explore the estimation precision of different forest and ground parameters from single baseline PolInSAR data in this tropical context.…”

Relating tropical forest biomass to P-band SAR tomography

“…The baselines have been spaced vertically with a spacing about 15 m (50ft ). Since the tomographic flight lines are in a vertical plane rather than in a horizontal plane, the phase to height factor has a small variation across the scene swath [8]. The vertical Fourier resolution is about ±10 m, whereas Paracou forest height ranges from 20 m to 40 m. Thanks to these features, image formation along the vertical direction has been carried out through a coherent focusing, without resorting to super-resolution techniques nor to model based approaches.…”

“…The aim of the study reported in this paper is to demonstrate the use of tomographic information to retrieve tropical forest biomass based on the experimental results from the Pband data acquired by ONERA in Paracou, French Guayana, in the frame of the ESA campaign TropiSAR 2009 [8].…”

The Impact of Temporal Decorrelation on BIOMASS Tomography of Tropical Forests

“…The investigation method is based on data from the airborne campaign TropiSAR 2009 [9] and the ground-based campaign TropiScat [10], [11], both carried out in the tropical forest site of Paracou, French Guiana, as part of BIOMASS Phase-A activities. Data from TropiSAR 2009 were used to generate a high-resolution 3-D reconstruction of the scattering elements within the Paracou forest, which was used as the basis for the retrieval of tropical forest biomass in [4] and [2] and for physical analysis in [12], [13].…”