| 1. |
- Banda, Francesco, et al.
(författare)
-
BIOMASS L2 Prototype Processor : Current Status
- 2019
-
Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS). - 9781538691540 ; , s. 5996-5999
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 2. |
- Banda, Francesco, et al.
(författare)
-
The BIOMASS level 2 prototype processor: Design and experimental results of above-ground biomass estimation
- 2020
-
Ingår i: Remote Sensing. - : MDPI AG. - 2072-4292. ; 12:6
-
Tidskriftsartikel (refereegranskat)abstract
- 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. We test the AGB retrieval using modified airborne P-Band data from the AfriSAR and TropiSAR campaigns together with reference data from LiDAR-based AGB maps and plot-based ground measurements. For AGB estimation based on data from a single heading, comparison with reference data yields relative Root Mean Square Difference (RMSD) values mostly between 20% and 30%. Combining different headings in the estimation process significantly improves the AGB retrieval to slightly less than 20%. The experimental results indicate that the implemented retrieval scheme provides robust results that are within mission requirements.
|
|
| 3. |
- Bruel, Laure, et al.
(författare)
-
HMI tests in simulator
- 2007
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The main goal of SASPENCE is to develop and evaluate an innovative system able to perform the Safe Speed and Safe Distance concept, that means to help the driver in avoiding accident situations related to excessive speed or too small headway. So, the system should co-operate seamlessly with the driver, suggesting the proper velocity for the given condition (road structure, traffic situation, etc.) preventing risky and dangerous situations and thus avoiding collision. This support is done through a Human Machine Interface (HMI). It is essential that the HMIs are easily understandable by the driver and that they induce a suitable reaction to the danger, otherwise the system is worthless. The simulator tests are the second step of the HMI design process that counts three of them. After the static tests that have enabled to show up the preferred visual, haptic and acoustic HMI, 8 combinations of HMI have been tested in dynamic conditions in the PSA driving simulator while part of the SASPENCE modules were running and tested. These tests should enable us to understand which HMIs are the best for the driver, that is to say, which HMI makes it possible to give the SASPENCE information in the clearest way to the driver. The main aims of these tests were to evaluate the effects of the SASPENCE system on drivers’ behaviour and to give recommendations for the HMI to be installed in the two test-cars, according to drivers’ preference and the efficiency of the HMI. They were also useful: - to improve the representativeness of the static tests results, - to check the good operation of some modules, that will be implemented in the test cars, and to check the good communication between the driver and the HMI, very early in the project, long before the demonstration cars are ready, - to complete the final road tests by measurements and observations in a more reproducible and observable conditions than the real road test. One interesting result of these tests is that the HMIs that were selected at the end of the static tests appeared to be too complex to be understood when one was driving. Another main result is that the SASPENCE system is efficient, as drivers spend less time in risky situations when driving with the SASPENCE system.
|
|
| 4. |
- D'Alessandro, Fabrizio, et al.
(författare)
-
Lean Catalytic Combustion for Ultra-low Emissions at High Temperature in Gas-Turbine Burners
- 2011
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 25, s. 136-143
-
Tidskriftsartikel (refereegranskat)abstract
- Catalytic systems for methane combustion, with Rh and Pt in a BaZrO3-based perovskite, were synthesized at the University of L'Aquila and tested at close to industrial conditions at the KTH Energy Centre in Stockholm. Because of the resistance to high temperature of BaZrO3 (up to similar to 2600 degrees C), such systems are suitable for resolving stability problems frequently encountered with high-temperature operations. Furthermore, these perovskites contain the noble metal in a high oxidation state, giving rise to very active compounds. They also result in ultra-low emissions, compatible with legislation in such places as southern California and Japan.
|
|
| 5. |
- Mariotti d'Alessandro, Mauro, et al.
(författare)
-
Interferometric Ground Cancellation for Above Ground Biomass Estimation
- 2020
-
Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892 .- 1558-0644. ; 58:9, s. 6410-6419
-
Tidskriftsartikel (refereegranskat)abstract
- A new processing technique, i.e., ground cancellation, which removes the ground signal from a pair of interferometric synthetic aperture radar (SAR) images, is used to emphasize the response from above-ground targets. This technique is of particular interest when studying forest canopies using low-frequency signals able to reach the underlying ground, in which case the portion of the signal coming from the ground interferes with the recovery of information about the vegetation. We demonstrate that the power in ground-canceled P-band HV SAR data gives significantly higher correlations with above-ground biomass (AGB) than the interferometric images considered separately. In addition, a significant increase in the sensitivity of backscatter to AGB is observed. Ground-canceled power may then be modeled or regressed to estimate AGB; these possibilities are not discussed here as they will be the topic of forthcoming publications. The effectiveness of this technique is proven through simulations and analysis of real data gathered on tropical forests. The stability of the technique is analyzed under the digital terrain model and baseline control errors, and compensation strategies for these errors are presented.
|
|
| 6. |
- Quegan, S., et al.
(författare)
-
The European Space Agency BIOMASS mission: Measuring forest above-ground biomass from space
- 2019
-
Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 227, s. 44-60
-
Tidskriftsartikel (refereegranskat)abstract
- The primary objective of the European Space Agency's 7th Earth Explorer mission, BIOMASS, is to determine the worldwide distribution of forest above-ground biomass (AGB) in order to reduce the major uncertainties in calculations of carbon stocks and fluxes associated with the terrestrial biosphere, including carbon fluxes associated with Land Use Change, forest degradation and forest regrowth. To meet this objective it will carry, for the first time in space, a fully polarimetric P-band synthetic aperture radar (SAR). Three main products will be provided: global maps of both AGB and forest height, with a spatial resolution of 200 m, and maps of severe forest disturbance at 50 m resolution (where “global” is to be understood as subject to Space Object tracking radar restrictions). After launch in 2022, there will be a 3-month commissioning phase, followed by a 14-month phase during which there will be global coverage by SAR tomography. In the succeeding interferometric phase, global polarimetric interferometry Pol-InSAR coverage will be achieved every 7 months up to the end of the 5-year mission. Both Pol-InSAR and TomoSAR will be used to eliminate scattering from the ground (both direct and double bounce backscatter) in forests. In dense tropical forests AGB can then be estimated from the remaining volume scattering using non-linear inversion of a backscattering model. Airborne campaigns in the tropics also indicate that AGB is highly correlated with the backscatter from around 30 m above the ground, as measured by tomography. In contrast, double bounce scattering appears to carry important information about the AGB of boreal forests, so ground cancellation may not be appropriate and the best approach for such forests remains to be finalized. Several methods to exploit these new data in carbon cycle calculations have already been demonstrated. In addition, major mutual gains will be made by combining BIOMASS data with data from other missions that will measure forest biomass, structure, height and change, including the NASA Global Ecosystem Dynamics Investigation lidar deployed on the International Space Station after its launch in December 2018, and the NASA-ISRO NISAR L- and S-band SAR, due for launch in 2022. More generally, space-based measurements of biomass are a core component of a carbon cycle observation and modelling strategy developed by the Group on Earth Observations. Secondary objectives of the mission include imaging of sub-surface geological structures in arid environments, generation of a true Digital Terrain Model without biases caused by forest cover, and measurement of glacier and icesheet velocities. In addition, the operations needed for ionospheric correction of the data will allow very sensitive estimates of ionospheric Total Electron Content and its changes along the dawn-dusk orbit of the mission.
|
|
| 7. |
- Soja, Maciej J., et al.
(författare)
-
MODEL-BASED ESTIMATION OF TROPICAL FOREST BIOMASS FROM NOTCH FILTERED P-BAND SAR BACKSCATTER
- 2018
-
Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS). ; 2018-July, s. 8617-8620
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a new algorithm for forest biomass estimation from P-band synthetic-aperture radar (SAR) backscatter data, notch-filtered at ground-level. A semi-empirical model is fitted to spatial and polarization trends in the backscatter data and no reference biomass data are needed for training. An evaluation on airborne P-band SAR data from a tropical test site in Gabon results in a root-mean-square error lower than 20% and a correlation better than 90%.
|
|
| 8. |
- Soja, Maciej, 1985, et al.
(författare)
-
Mapping above-ground biomass in tropical forests with ground-cancelled P-band SAR and limited reference data
- 2021
-
Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 253
-
Tidskriftsartikel (refereegranskat)abstract
- This paper introduces the CASINO (CAnopy backscatter estimation, Subsampling, and Inhibited Nonlinear Optimisation) algorithm for above-ground biomass (AGB) estimation in tropical forests using P-band (435 MHz) synthetic aperture radar (SAR) data. The algorithm has been implemented in a prototype processor for European Space Agency's (ESA's) 7th Earth Explorer Mission BIOMASS, scheduled for launch in late 2022. CASINO employs an interferometric ground cancellation technique to estimate canopy backscatter (CB) intensity. A power law model (PLM) is then used to model the dependence of CB on AGB for a large number of systematically distributed SAR data samples and a small number of calibration areas with a known AGB. The PLM parameters and AGB for the samples are estimated simultaneously within pre-defined intervals using nonlinear minimisation of a cost function. The performance of CASINO is assessed over six tropical forest sites on two continents: two in French Guiana, South America and four in Gabon, Africa, using SAR data acquired during airborne ESA campaigns and processed to simulate BIOMASS acquisitions. Multiple tests with only two randomly selected calibration areas with AGB > 100 t/ha are conducted to assess AGB estimation performance given limited reference data. At 2.25 ha scale and using a single flight heading, the root-mean-square difference (RMSD) is ≤ 27% for at least 50% of all tests in each test site and using as reference AGB maps derived from airborne laser scanning data. An improvement is observed when two flight headings are used in combination. The most consistent AGB estimation (lowest RMSD variation across different calibration sets) is observed for test sites with a large AGB interval and average AGB around 200–250 t/ha. The most challenging conditions are in areas with AGB < 200 t/ha and large topographic variations. A comparison with 142 1 ha plots distributed across all six test sites and with AGB estimated from in situ measurements gives an RMSD of 20% (66 t/ha).
|
|
| 9. |
- Tebaldini, S., et al.
(författare)
-
Biomass Level-2 Products - Part II: Processing Schemes and AGB Estimation Results from Campaign Data
- 2021
-
Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS). ; 2021-July, s. 783-786
-
Konferensbidrag (refereegranskat)abstract
- Scheduled for launch in 2023, ESA's seventh Earth Explorer Mission, BIOMASS, will carry the first P-band synthetic aperture radar (SAR) to be flown in space, to gather fully polarimetric acquisitions over forested areas worldwide in interferometric and tomographic modes. This paper presents the algorithms developed to estimate biophysical parameters from BIOMASS measurements and their implementation in the BIOMASS level 2 (L2) prototype processor. The L2 processor will generate global maps of forest Above Ground Biomass (AGB), Forest Height (FH), Forest disturbance (FD). Accurate generation of these products requires the L2 processor to be closely inter-linked with the BIOMASS interferometric processor, in order to produce phase-calibrated interferometric stacks, retrieve sub-canopy terrain topography, and generate a 3D representation of forest structure by use of SAR tomography. AGB estimation results are here shown using BIOMASS-like acquisitions derived from campaign data acquired over six tropical forests in South America and Equatorial Africa.
|
|
| 10. |
- Tebaldini, S., et al.
(författare)
-
THE TOMOSENSE EXPERIMENT: MONO- AND BISTATIC SAR TOMOGRAPHY OF FORESTED AREAS AT P-, L-, AND C-BAND
- 2021
-
Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS). ; 2021-July, s. 7955-7958
-
Konferensbidrag (refereegranskat)abstract
- The TomoSense experiment comprises campaign and research activities in support of future Synthetic Aperture Radar (SAR) mission concepts at P-, L-, and C-band by the European Space Agency (ESA). The research is intended to provide a quantitative basis for the evaluation of single-pass interferometry over temperate forests at L- and C-band and investigate potential synergies between C-band convoy mission concepts and future P- and L-band missions. SAR acquisitions include P- L-, and C-band data acquired at the Eifel National Park in Germany by flying approximately 25 trajectories to provide tomographic imaging capabilities. L- and C-band data were acquired by simultaneously flying two aircraft to gather bistatic data with varying interferometric baselines. Field activities include forest census (dbh, tree height and species) at 80 plots and Terrestrial Laser Scanning (TLS). The dataset is complemented by small-footprint Airborne Lidar Scanning (ALS) and derived products. Preliminary results are here shown relative to polarimetric tomography at P-band and L-band imaging.
|
|
