International audienceInterest in the world forests has grown to unprecedented heights, especiall... more International audienceInterest in the world forests has grown to unprecedented heights, especially with growing awareness of their role in the global carbon cycle. Quantifying carbon in forests is therefore of crucial importance for estimating carbon fluxes at the regional and global scale. Carbon quantities are estimated by inferring wood biomass from forest biomass, and then converting it into carbon by using a value of approximately 0.5 ton of carbon for 1 ton of wood. In order to determine the bio-mass of a forest, significant relationships have therefore been established between radar mean intensity and biophysical variables. However, for mature stands (about 80 t/ha and more) increasing biomass reduces the sensitivity of the backscattering coefficient sigma/biomass relationships. Recent studies have shown that texture could be used instead of the usual intensity-age relationships, even for mature stands up to 140 t/ha, the highest biomass value observed for studied forests (mo...
Quantifying forest biomass is of crucial importance for estimating carbon fluxes on the regional ... more Quantifying forest biomass is of crucial importance for estimating carbon fluxes on the regional and global scale in climate change studies. Significant relationships have already been established between radar mean intensity and forest biomass, but these relationships show a reduced sensitivity to biomass variations for mature stands (about 80 t/ha and more). On the contrary, recent studies have shown that image texture is significantly related to biomass even for mature stands for a temperate, monospecific, even-aged forest the biomass of which is 140 t/ha at its highest point. The present paper aims at extending these observations to tropical forests which represent a large terrestrial biomass pool with values higher than 450 t/ha. Radar images were acquired during the TropiSAR experiment in 2009, which took place over a tropical rain forest located in French Guiana at P band and cross-polarization with the use of SETHI ONERA airborne instrument. Three sets of treatments applied ...
2019 European Microwave Conference in Central Europe (EuMCE), 2019
In the context of the SMOS and the BIOMASS space-borne mission, the data processing algorithms re... more In the context of the SMOS and the BIOMASS space-borne mission, the data processing algorithms require precise permittivity models of different wood species. To develop the models, in situ sensors that could be easily deployed on the site dedicated to calibration/validation studies would be very relevant. Microwave volume analysis can be a very useful tool to monitor wood properties. There are very few commercial equipment dedicated to in-situ measurements and none of them is developed in order to leave the instrument on site for automatic measurements with specific constraints such as communication, low power consumption, large frequency broadband, non-invasive measurement and low price. The main objective of the study presented is to develop an equipment to meet these challenges.In this article we will present the design of the broadband antennas used in the device to perform efficient in situ measurements. Preliminary results obtained over a concrete structure demonstrate the pos...
IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium, 2019
The ESA BIOMASS mission will be the 7th Earth Explorer measuring the above-ground biomass (AGB) i... more The ESA BIOMASS mission will be the 7th Earth Explorer measuring the above-ground biomass (AGB) in the world’s forests. The current ESA Level-2 (L2) implementation study focuses on defining and implementing the main algorithms for forest parameter retrieval from BIOMASS data. After the first year of L2 study innovative results were achieved: the development of ground cancellation, in particular, has proved to be huge value, since it removes from the data the effects of environmental variability and contributions unrelated to the forest carried in the ground scattering. In this paper the current processor implementation and validation activities of the L2 team will be described.
Ho Chi Minh City (HCMC), the most populous city and the economic center of Viet Nam, has faced gr... more Ho Chi Minh City (HCMC), the most populous city and the economic center of Viet Nam, has faced ground subsidence in recent decades. This work aims at providing an unprecedented spatial extent coverage of the subsidence in HCMC in both horizontal and vertical components using Interferometric Synthetic Aperture Radar (InSAR) time series. For this purpose, an advanced InSAR technique PSDS (Permanent Scatterers and Distributed Scatterers) was applied to two big European Space Agency (ESA) Sentinel-1 datasets composed of 96 ascending and 202 descending images, acquired from 2014 to 2020 over HCMC area. A time series of 33 Cosmos SkyMED images was also used for comparison purpose. The combination of ascending and descending satellite passes allows the decomposition of the light of sight velocities into horizontal East-west and vertical components. By taking into account the presence of the horizontal East-west movement, our finding indicates that the precision of the decomposed vertical v...
BIOMASS is ESA’s seventh Earth Explorer mission, scheduled for launch in 2022. The satellite will... more BIOMASS is ESA’s seventh Earth Explorer mission, scheduled for launch in 2022. The satellite will be the first P-band SAR sensor in space and will be operated in fully polarimetric interferometric and tomographic modes. The mission aim is to map forest above-ground biomass (AGB), forest height (FH) and severe forest disturbance (FD) globally with a particular focus on tropical forests. This paper presents the algorithms developed to estimate these biophysical parameters from the BIOMASS level 1 SAR measurements and their implementation in the BIOMASS level 2 prototype processor with a focus on the AGB product. The AGB product retrieval uses a physically-based inversion model, using ground-canceled level 1 data as input. The FH product retrieval applies a classical PolInSAR inversion, based on the Random Volume over Ground Model (RVOG). The FD product will provide an indication of where significant changes occurred within the forest, based on the statistical properties of SAR data. W...
International audienceInterest in the world forests has grown to unprecedented heights, especiall... more International audienceInterest in the world forests has grown to unprecedented heights, especially with growing awareness of their role in the global carbon cycle. Quantifying carbon in forests is therefore of crucial importance for estimating carbon fluxes at the regional and global scale. Carbon quantities are estimated by inferring wood biomass from forest biomass, and then converting it into carbon by using a value of approximately 0.5 ton of carbon for 1 ton of wood. In order to determine the bio-mass of a forest, significant relationships have therefore been established between radar mean intensity and biophysical variables. However, for mature stands (about 80 t/ha and more) increasing biomass reduces the sensitivity of the backscattering coefficient sigma/biomass relationships. Recent studies have shown that texture could be used instead of the usual intensity-age relationships, even for mature stands up to 140 t/ha, the highest biomass value observed for studied forests (mo...
Quantifying forest biomass is of crucial importance for estimating carbon fluxes on the regional ... more Quantifying forest biomass is of crucial importance for estimating carbon fluxes on the regional and global scale in climate change studies. Significant relationships have already been established between radar mean intensity and forest biomass, but these relationships show a reduced sensitivity to biomass variations for mature stands (about 80 t/ha and more). On the contrary, recent studies have shown that image texture is significantly related to biomass even for mature stands for a temperate, monospecific, even-aged forest the biomass of which is 140 t/ha at its highest point. The present paper aims at extending these observations to tropical forests which represent a large terrestrial biomass pool with values higher than 450 t/ha. Radar images were acquired during the TropiSAR experiment in 2009, which took place over a tropical rain forest located in French Guiana at P band and cross-polarization with the use of SETHI ONERA airborne instrument. Three sets of treatments applied ...
2019 European Microwave Conference in Central Europe (EuMCE), 2019
In the context of the SMOS and the BIOMASS space-borne mission, the data processing algorithms re... more In the context of the SMOS and the BIOMASS space-borne mission, the data processing algorithms require precise permittivity models of different wood species. To develop the models, in situ sensors that could be easily deployed on the site dedicated to calibration/validation studies would be very relevant. Microwave volume analysis can be a very useful tool to monitor wood properties. There are very few commercial equipment dedicated to in-situ measurements and none of them is developed in order to leave the instrument on site for automatic measurements with specific constraints such as communication, low power consumption, large frequency broadband, non-invasive measurement and low price. The main objective of the study presented is to develop an equipment to meet these challenges.In this article we will present the design of the broadband antennas used in the device to perform efficient in situ measurements. Preliminary results obtained over a concrete structure demonstrate the pos...
IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium, 2019
The ESA BIOMASS mission will be the 7th Earth Explorer measuring the above-ground biomass (AGB) i... more The ESA BIOMASS mission will be the 7th Earth Explorer measuring the above-ground biomass (AGB) in the world’s forests. The current ESA Level-2 (L2) implementation study focuses on defining and implementing the main algorithms for forest parameter retrieval from BIOMASS data. After the first year of L2 study innovative results were achieved: the development of ground cancellation, in particular, has proved to be huge value, since it removes from the data the effects of environmental variability and contributions unrelated to the forest carried in the ground scattering. In this paper the current processor implementation and validation activities of the L2 team will be described.
Ho Chi Minh City (HCMC), the most populous city and the economic center of Viet Nam, has faced gr... more Ho Chi Minh City (HCMC), the most populous city and the economic center of Viet Nam, has faced ground subsidence in recent decades. This work aims at providing an unprecedented spatial extent coverage of the subsidence in HCMC in both horizontal and vertical components using Interferometric Synthetic Aperture Radar (InSAR) time series. For this purpose, an advanced InSAR technique PSDS (Permanent Scatterers and Distributed Scatterers) was applied to two big European Space Agency (ESA) Sentinel-1 datasets composed of 96 ascending and 202 descending images, acquired from 2014 to 2020 over HCMC area. A time series of 33 Cosmos SkyMED images was also used for comparison purpose. The combination of ascending and descending satellite passes allows the decomposition of the light of sight velocities into horizontal East-west and vertical components. By taking into account the presence of the horizontal East-west movement, our finding indicates that the precision of the decomposed vertical v...
BIOMASS is ESA’s seventh Earth Explorer mission, scheduled for launch in 2022. The satellite will... more BIOMASS is ESA’s seventh Earth Explorer mission, scheduled for launch in 2022. The satellite will be the first P-band SAR sensor in space and will be operated in fully polarimetric interferometric and tomographic modes. The mission aim is to map forest above-ground biomass (AGB), forest height (FH) and severe forest disturbance (FD) globally with a particular focus on tropical forests. This paper presents the algorithms developed to estimate these biophysical parameters from the BIOMASS level 1 SAR measurements and their implementation in the BIOMASS level 2 prototype processor with a focus on the AGB product. The AGB product retrieval uses a physically-based inversion model, using ground-canceled level 1 data as input. The FH product retrieval applies a classical PolInSAR inversion, based on the Random Volume over Ground Model (RVOG). The FD product will provide an indication of where significant changes occurred within the forest, based on the statistical properties of SAR data. W...
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Papers by Thuy Le Toan