An Observing System Simulation Experiment for the Aquarius/SAC-D Soil Moisture Product

CINTIA BRUSCANTINI; WADE T. CROW; FRANCISCO GRINGS; PABLO PERNA; MARTÍN MAAS; HAYDEE KARSZENBAUM

IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Lugar: New York; Año: 2014 vol. 52 p. 6086 - 6094

0196-2892

An Observing System Simulation Experiment(OSSE) for the Aquarius/SAC-D mission has been developed forassessing the accuracy of soil moisture retrievals from passiveL-band remote sensing. The implementation of the OSSE isbased on the following: a 1-km land surface model over theRed-Arkansas River Basin, a forward microwave emissionmodel to simulate the radiometer observations, a realistic orbitaland sensor model to resample the measurements mimickingAquarius operation, and an inverse soil moisture retrieval model.The simulation implements a zero-order radiative transfermodel. Retrieval is performed by direct inversion of the forwardmodel. The Aquarius OSSE attempts to capture the influenceof various error sources, such as land surface heterogeneity, instrumentnoise, and retrieval ancillary parameter uncertainty,all on the accuracy of Aquarius surface soil moisture retrievals.In order to assess the impact of these error sources on theestimated volumetric soil moisture, a quantitative error analysisis performed by comparison of footprint-scale synthetic soilmoisture with ?true? soil moisture fields obtained from the directaggregation of the original 1-km soil moisture field input to theforward model. Results show that, in heavily vegetated areas, soilmoisture retrievals have a positive bias that can be suppressedwith an alternative aggregation strategy for ancillary parametervegetation water content (VWC). Retrieval accuracy was alsoevaluated when adding errors to 1-km VWC (which are intendedto account for errors in VWC derived from remote sensing data).For soil moisture retrieval root-mean-square error on the order of0.05 m3/m3, the error in VWC should be less than 12%.