An Observing System Simulation Experiment for the Aquarius/SAC-D Soil Moisture Product
Transactions on Geoscience and Remote Sensing, IEEE , vol.52, no.10, pp.6086,6094, Oct. 2014
doi: 10.1109/TGRS.2013.2294915
Abstract: An Observing System Simulation Experiment (OSSE) for the Aquarius/SAC-D mission has been developed for assessing the accuracy of soil moisture retrievals from passive L-band remote sensing. The implementation of the OSSE is based on the following: a 1-km land surface model over the Red-Arkansas River Basin, a forward microwave emission model to simulate the radiometer observations, a realistic orbital and sensor model to resample the measurements mimicking Aquarius operation, and an inverse soil moisture retrieval model.
The simulation implements a zero-order radiative transfer model. Retrieval is performed by direct inversion of the forward model. The Aquarius OSSE attempts to capture the influence of various error sources, such as land surface heterogeneity, instrument noise, 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 the estimated volumetric soil moisture, a quantitative error analysis is performed by comparison of footprint-scale synthetic soil moisture with “true” soil moisture fields obtained from the direct aggregation of the original 1-km soil moisture field input to the forward model. Results show that, in heavily vegetated areas, soil moisture retrievals have a positive bias that can be suppressed with an alternative aggregation strategy for ancillary parameter vegetation water content (VWC). Retrieval accuracy was also evaluated when adding errors to 1-km VWC (which are intended to account for errors in VWC derived from remote sensing data).
For soil moisture retrieval root-mean-square error on the order of 0.05 m3 /m3 , the error in VWC should be less than 12%.
Index Terms—Aquarius, Observing System Simulation Experiment (OSSE), soil moisture.
keywords: {hydrological techniques;inverse problems; microwave measurement;moisture measurement; radiative transfer; radiometry; remote sensing;soil; vegetation; Aquarius OSSE; Aquarius operation; Aquarius surface soil moisture retrieval; Aquarius/SAC-D mission; Aquarius/SAC-D soil moisture product; Observing System Simulation Experiment; Red-Arkansas River Basin; USA; VWC; aggregation strategy; ancillary parameter vegetation water content; direct forward model inversion; error sources; footprint-scale synthetic soil moisture;forward microwave emission model; heavily vegetated area;instrument noise; inverse soil moisture retrieval model; land surface heterogeneity; land surface model; orbital model; passive L-band remote sensing; quantitative error analysis; radiometer observation simulation; remote sensing data; retrieval ancillary parameter uncertainty; sensor model; soil moisture field; soil moisture retrieval root-mean-square error; volumetric soil moisture; zero-order radiative transfer model; Accuracy; Land surface; Noise; Soil measurements; Soil moisture; Spatial resolution; Aquarius; Observing System Simulation Experiment (OSSE); soil moisture},
URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6725671&isnumber=6819879