A nonlinear optimization algorithm for windsat wind vector retrievals. IEEE Trans Geosci Rem Sen

Remote Sensing Div., Naval Res. Lab., Washington, DC, USA
IEEE Transactions on Geoscience and Remote Sensing (Impact Factor: 3.51). 04/2006; 44(3):597 - 610. DOI: 10.1109/TGRS.2005.862504
Source: IEEE Xplore


WindSat is a space-based polarimetric microwave radiometer designed to demonstrate the capability to measure the ocean surface wind vector using a radiometer. We describe a nonlinear iterative algorithm for simultaneous retrieval of sea surface temperature, columnar water vapor, columnar cloud liquid water, and the ocean surface wind vector from WindSat measurements. The algorithm uses a physically based forward model function for the WindSat brightness temperatures. Empirical corrections to the physically based model are discussed. We present evaluations of initial retrieval performance using a six-month dataset of WindSat measurements and collocated data from other satellites and a numerical weather model. We focus primarily on the application to wind vector retrievals.

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Available from: R. M. Bevilacqua, Nov 21, 2014
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    • "MIS will use a 1.8-m rotating main reflector to cover a 1700-km swath width while measuring over a frequency range of 6–183 GHz. MIS will produce operational ocean surface wind vectors using methodology developed for WindSat (e.g., Bettenhausen et al. 2006) with validated wind speeds up to about 25 m s "
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    ABSTRACT: This article that describes NPOESS was completed and accepted for publication prior to the White House decision in February 2010 ordering a major restructuring of the NPOESS program. NOAA will now assume primary responsibility for the afternoon polar-orbiting operational environmental satellite orbit and DoD will take primary responsibility for the early morning orbit. However, NPP, as described in this article, is still scheduled to be launched in 2011. Several of the instruments and program elements described in this article are also likely to be carried forward into future U.S. polar-orbiting operational environmental satellite missions.
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    • "It is well known that, when dealing with the retrieval of wind direction, the problem of the non-uniqueness of the solution is fairly significant. The cost function may have many local minima and different solutions (generally indicated as ambiguities) can be obtained depending on the first guess value of φ̃ (hereafter denoted as φ̃fg) [1], [11,12]. We have searched for the four ambiguities, as done in [12], so that the procedure illustrated in Figure 4 has been applied four times (for each TB of the ECMWF-SW2 test set), each time using a different φ̃fg. "
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    ABSTRACT: A simulation study to assess the potentiality of sea surface wind vector estimation based on the approximation of the forward model through Neural Networks and on the Bayesian theory of parameter estimation is presented. A polarimetric microwave radiometer has been considered and its observations have been simulated by means of the two scale model. To perform the simulations, the atmospheric and surface parameters have been derived from ECMWF analysis fields. To retrieve wind speed, Minimum Variance (MV) and Maximum Posterior Probability (MAP) criteria have been used while, for wind direction, a Maximum Likelihood (ML) criterion has been exploited. To minimize the cost function of MAP and ML, conventional Gradient Descent method, as well as Simulated Annealing optimization technique, have been employed. Results have shown that the standard deviation of the wind speed retrieval error is approximately 1.1 m/s for the best estimator. As for the wind direction, the standard deviation of the estimation error is less than 13° for wind speeds larger than 6 m/s. For lower wind velocities, the wind direction signal is too weak to ensure reliable retrievals. A method to deal with the non-uniqueness of the wind direction solution has been also developed. A test on a case study has yielded encouraging results.
    Full-text · Article · Dec 2008 · Sensors
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    • "The polar-orbiting WindSat instrument is a multifrequency polarimetric microwave radiometer (Gaiser 2004) developed by the Naval Research Laboratory (NRL). WindSat vector wind observations are generated at Fleet Numerical Meteorology and Oceanography Center (FNMOC) from raw radiances using software developed by NRL (Bettenhausen et al. 2006). The operational assimilation of WindSat winds into the Navy Operational Global Atmospheric Prediction System (NOGAPS; Hogan and Rosmond 1991) at FNMOC was initiated in December 2006. "

    Full-text · Article · Jan 2007
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