Validation campaign : BUSARD
In February 2011, first campaign for SWOT preparation
The instrument that will fly on board SWOT is a radar interferometer in Ka Band. There is few studies of retrodiffusion by natural surfaces in this frequency band, in peculiar for a near nadir geometry. These studies are concerning a low diversity of surface types and small number of associated parameters (with narrow variation range) : incidence angle, soil humidity and rugosity, and over sea, water salinity and waves height.
Simulators have been developped by JPL and CNES, taking into account radiometric and geometric aspects. It is necessary to validate these results using ground truth in flight measurements.
2.1 the instrument
During the campaign, DRIVE radar flying on board moto glidder BUSARD, both ONERA means, have been operated.
DRIVE and BUSARD on ONERA website (in French)
DRIVE is a band Ka radar. It is operated in interferometric mode short base (18 cm) or long base (4,7 m) .
Flying altitude is 3000m and swath path is 700m. Measurements are acquired along 5 km segments (2 minutes).
2.2 Observation site
The DRIVE/BUSARD campaign for SWOT was operated during the first 2011 semestre in Camargue.Space measurements has been coupled with ground measurements for wind speed, water and soil rugosity, soil wetness, vegetation parameters, as welle as altitude and slopes measurements, allowing comparisons with models and simulations.
Interferometrics measurements were settled above several sites : Rhône river south Arles, coast at Piemanson and around a buoy in the Mediterranean sea.
First acquisition in Ka band, incidences from 0 to 14°
(concerning KaRIn/SWOT, incidences will be between 0.6° and 4.1°)
The radar image is nearly 1800 m long and 750m wide. Vertical mesurements are at the top of the image and the bottom corresponds to incidence 14°.
La bright zone is Rhône river and "berges" are darker.