Time series of salt crusts imaged by a dual polarization spaceborne Synthetic Aperture Radar (SAR) at C-band over an Andean Atiplano Salar of Northern Chile

BARBER, MATIAS; DELSOUC, ANALIA; PÉREZ-MARTÍNEZ, WALDO; BRICEÑO-DE-URBANEJA, IDANIA

Santiago

Conferencia; LAGIRS 2020: 2020 Latin American GRSS & ISPRS Remote Sensing Conference; 2020

Universidad de Chile y Universidad de Magallanes

A dense time seriesof Synthetic Aperture Radar acquisitions at 6-day intervals betweenJuly 2017 to January 2019 collected with the C-band constellationSentinel 1A and 1B is used to study salt crust evolution in anhighland salar. Microwave response of halite crystal aggregates islinked to surface roughness of the salt crusts by means of a surfacescattering model which includes multiple scattering at second orderin media with complex permittivity such as brine-soil mixtures. Thetime series enabled to estimate co-polarised vertical-verticalbackscattering coefficient variations as large as 8.8 dB on a 4-monthperiod which implied a height standard deviation increase from 0.5 to4.5 mm as modeled by the surface scattering model. Backscatteringcoefficient variations between 0.8 to 2 dB per month are found forthree different crusts, which demonstrated different growth rates ofthe crystals. Crystal growth rate might be driven by the kind ofwater input (rainfall or snow in Andean salars), probably due to thenegative effect of water droplets on impinging halite crystal surfacein comparison to snow. Results showed that cross-polarisedbackscattering coefficient is sensitive to snow accumulation andappeared to be insensitivity to other weather conditions.p { margin-bottom: 0.1in; line-height: 120% }