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Validation of radiometric models and simulated KaRIn/SWOT data based on ground and airborne acquisitions Roger Fjørtoft, Jean-Claude Lalaurie, Nadine Pourthie,

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Presentation on theme: "Validation of radiometric models and simulated KaRIn/SWOT data based on ground and airborne acquisitions Roger Fjørtoft, Jean-Claude Lalaurie, Nadine Pourthie,"— Presentation transcript:

1 Validation of radiometric models and simulated KaRIn/SWOT data based on ground and airborne acquisitions Roger Fjørtoft, Jean-Claude Lalaurie, Nadine Pourthie, Christine Lion, Jean-Marc Gaudin, Alain Mallet (CNES, Toulouse, France), Jean-François Nouvel, Pierre Borderies (ONERA, Toulouse/Salon de Provence, France), Pascal Kosuth (CEMAGREF, Montpellier, France), Christian Ruiz (Capgemini, Toulouse, France). IGARSS 2011, Vancouver, Canada, July 2011

2 SWOT IGARSS 2011, Vancouver, Canada, July Outline ■Introduction  Context, objectives  Specificities of KaRIn/SWOT interferometric SAR data ■Modeling and simulation  Backscattering from various surfaces  Simulation of raw and SLC radar images ■Airborne acquisitions  First interferometric Ka-band acquisitions including the KaRIn incidence range (1-4°) ■Near-field Ka-band measurements  Water backscattering as a function of wind speed and surface roughness

3 SWOT IGARSS 2011, Vancouver, Canada, July Introduction ■Context  Original InSAR configuration of KaRIn/SWOT: Ka-band, near-nadir (1-4°)  Very limited bibliography on backscattering from natural surfaces  Modeling of Ka-band backscattering (  0 )  As a function of surface type, surface conditions, incidence angle, …  Simulation of raw (L0) and SLC (L1) KaRIn/SWOT interferometric data  Radiometry and geometry ■Objective: Realize airborne and near-field Ka-band acquisitions  Compare models and simulations with real data (validate, improve)  Need for ground truth  Study important phenomena w.r.t. feasibility and performance  Coherence, land/water contrast, layover, …  Enable more realistic input data for algorithm development and testing  Airborne data and improved simulated images

4 SWOT IGARSS 2011, Vancouver, Canada, July BUSARD/DRIVE airborne acquisitions (1/2) ■BUSARD is a Stemme motor-glider operated by ONERA ■DRIVE Ka-band radar integrated in POD ■Interferometry with short (18 cm) or long (4.7 m) baseline ■2.5 W amplifier ■Near-nadir acquisitions (0-14°) with 18 cm baseline in 2011 ■Altitude: 3000 m (9500 ft) ■Swath: 700 m ■Acquisition length: 5 km (2 min) ■PRF: 1250 Hz ■Integration time: 0.2 s

5 SWOT IGARSS 2011, Vancouver, Canada, July BUSARD/DRIVE airborne acquisitions (2/2) ■Simultaneous ground truth:  Wind speed  Water surface roughness  Water surface height and slope  Wave height (buoys)  Soil humidity ■Same day/week/month:  Soil roughness  Vegetation characteristics  Landcover ■Available static data:  Digital maps  DEM

6 SWOT IGARSS 2011, Vancouver, Canada, July Espiguette (buoy) Acquisition sites in the Camargue area (2011) Piemanson Vaccarès Rhône

7 SWOT IGARSS 2011, Vancouver, Canada, July Amplitude voie a ~700 m 0° 13° ~2,6 km ~1° 0° ~4° ~10° Trihedrals Artifacts due to wide antenna lobe (right/ left contamination) DRIVE/BUSARD acquisition 24/02/2011 (Rhône)

8 SWOT IGARSS 2011, Vancouver, Canada, July DRIVE/BUSARD acquisition 24/02/2011 (Rhône) Phase (interferogram)

9 SWOT IGARSS 2011, Vancouver, Canada, July DRIVE/BUSARD acquisition 24/02/2011 (Rhône) Coherence >0.9 ~0.7 ~0.3

10 SWOT IGARSS 2011, Vancouver, Canada, July Amplitude DRIVE/BUSARD acquisition 14/04/2011 (Vaccarès)

11 SWOT IGARSS 2011, Vancouver, Canada, July DRIVE/BUSARD acquisition 14/04/2011 (Vaccarès) Amplitude 1 Amplitude 2 Coherence Phase

12 SWOT IGARSS 2011, Vancouver, Canada, July DRIVE/BUSARD acquisition 14/04/2011 (Espiguette) Amplitude

13 SWOT IGARSS 2011, Vancouver, Canada, July DRIVE/BUSARD acquisition 14/04/2011 (Espiguette) Amplitude 1 Amplitude 2 Coherence Phase

14 SWOT IGARSS 2011, Vancouver, Canada, July Amplitude DRIVE/BUSARD acquisition 25/05/2011 (Rhône)

15 SWOT IGARSS 2011, Vancouver, Canada, July Near-field measurements in Ka-band (1/2) ■Near-field Ka-band measurements of  0 of water with a network analyzer and an automatically steerable (0-10°) parabolic antenna (ONERA) ■Simultaneous measurement of water surface roughness (using immerged pressure sensors) and wind speed (CEMAGREF) ■Rapidly varying wind conditions make the interpretation of the first results complicated.

16 SWOT IGARSS 2011, Vancouver, Canada, July Near-field measurements in Ka-band (2/2) ■Acquisitions in the Large Air-Sea Interaction Facility (LASIF) at IRPHE (Luminy): 40 m wind tunnel + 40 m water tank ■Possibility to study wind-generated water roughness (waves) in stable conditions (as well as to add mechanically generated waves) ■Additional equipment for optical roughness characterization (IRPHE) ■Comparison of  0 profiles with radiometric models (CapGemini)

17 SWOT IGARSS 2011, Vancouver, Canada, July Water  0 as a function of wind speed Incidence (°/100)  0 (dB) Wind parallel to incidence direction Wind perpendicular to incidence direction  0 (dB) Incidence (°/100)

18 SWOT IGARSS 2011, Vancouver, Canada, July Conclusion ■Airborne acquisitions with DRIVE/BUSARD  First interferometric Ka-band acquisitions including the near-nadir incidence range of KaRIn/SWOT (1-4°)  Confirmation of main feasibility and measurement physics assumptions  Will allow to refine models and simulators  Experience gained w.r.t. InSAR processing and ground truth collection  Hydrology, coastal and ocean test sites covered; possible extension to other surface types: forest, snow/ice, … ■Near field measurements of water surfaces   0 as a function of incidence and wind speed / surface roughness  Interesting phenomena observed; comparison with models ongoing  Wind-generated roughness only; possibility of adding waves mechanically  Complementary in situ and wind/water tank measurements


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