Author:
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Valencia Domènech, Enric; Camps Carmona, Adriano José; Bosch Lluís, Xavier; Rodríguez Álvarez, Nereida; Ramos Pérez, Isaac; Eugenio, Francisco Javier; Marcello, Javier
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Abstract:
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Sea surface salinity is a key oceanographic parameter that can be measured by means of L-band microwave radiometry. The measured brightness temperatures over the ocean are
influenced by the sea state, which can entirely mask the salinity signature. Sea-state corrections parameterized in terms of wind speed and/or significant wave height have proven not to be fully satisfactory. In 2003, it was proposed to use reflectometry using navigation opportunity signals [Global Navigation Satellite System Reflectometer (GNSS-R)] for sea-state determination and correction of the measured L-band brightness temperature changes associated to the sea state. The novelty of the approach relies in the measurement of the whole Delay-Doppler Map that captures the scattering of the GNSS signals in the whole glistening zone. In this
framework, the “Advanced L-BAnd emissiviTy and Reflectivity Observations of the Sea Surface” (ALBATROSS) field experiments
were undertaken in 2008 and 2009, collecting an extensive data set of collocated radiometric and reflectometric measurements over the Atlantic Ocean, as well as oceanographic and meteorological data. In this paper, the experimental results and conclusions of the ALBATROSS 2009 field experiment are compiled and presented,
showing the great potential of this technique to perform the necessary
corrections in future salinity missions. Empirical relationships are derived among measured brightness temperature variations
due to the sea-state effect and direct GNSS-R observables, and the sea surface correlation time at L1 band, a key parameter
for GNSS-R data processing since it determines the maximum coherent integration time, was experimentally determined. |