SWOT Validation campaign: BUSARD

In February 2011, first campaign for SWOT  preparation

Objectives

The instrument that will fly on board SWOT is a radar interferometer in Ka Band. There is few studies of  backscatter 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 roughness, and over sea, water salinity and waves height.
Simulators have been developed by  JPL and CNES, taking into account radiometric and geometric aspects.  It is necessary to validate these results using ground truth in flight measurements.

Means

DRIVE and BUSARD on ONERA website (in French) http://www.onera.fr/vo-laboratoire/2005-11.php

The instrument

During the campaign, DRIVE radar flying on  board moto glidder BUSARD, both ONERA means,  have been operated.
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).
 

Observation site

The  DRIVE/BUSARD campaign for SWOT was operated during the first 2011 semester in Camargue.Space measurements has been coupled  with ground  measurements for wind speed, water and soil roughness,  soil wetness, vegetation parameters, as well 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.

Results

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°.
The bright zone is Rhône river, with its banks darker.