igarss 2011, vancouver, canada, 25-29 july 2011
DESCRIPTION
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 ), - PowerPoint PPT PresentationTRANSCRIPT
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, 25-29 July 2011
IGARSS 2011, Vancouver, Canada, 25-29 July 2011 2SWOT
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
IGARSS 2011, Vancouver, Canada, 25-29 July 2011 3SWOT
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
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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
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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
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Espiguette (buoy)
Acquisition sites in the Camargue area (2011)
Piemanson
Vaccarès
Rhône
IGARSS 2011, Vancouver, Canada, 25-29 July 2011 7SWOTAmplitude
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)
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DRIVE/BUSARD acquisition 24/02/2011 (Rhône)
Phase (interferogram)
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DRIVE/BUSARD acquisition 24/02/2011 (Rhône)
Coherence
>0.9~0.7
~0.3
IGARSS 2011, Vancouver, Canada, 25-29 July 2011 10SWOTAmplitude
DRIVE/BUSARD acquisition 14/04/2011 (Vaccarès)
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DRIVE/BUSARD acquisition 14/04/2011 (Vaccarès)
Amplitude 1 Amplitude 2 Coherence Phase
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DRIVE/BUSARD acquisition 14/04/2011 (Espiguette)
Amplitude
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DRIVE/BUSARD acquisition 14/04/2011 (Espiguette)
Amplitude 1 Amplitude 2 Coherence Phase
IGARSS 2011, Vancouver, Canada, 25-29 July 2011 14SWOTAmplitude
DRIVE/BUSARD acquisition 25/05/2011 (Rhône)
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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.
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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)
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Water 0 as a function of wind speed
Incidence (°/100)
0 (
dB
)
Wind parallel to incidence directionWind perpendicular to incidence direction
0 (
dB
)
Incidence (°/100)
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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 surfaces0 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