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Math and StatisticsStatistics and Probability

Error Covariance Estimation and Representation for Mesoscale Data Assimilation

Authors: Qin Xu; OKLAHOMA UNIV NORMAN OFFICE OF RESEARCH SERVICES
Abstract:
The goal of this project is to explore and develop new methods of error covariance estimation and representation that can improve mesoscale data assimilation and numerical weather prediction. To this end, three research objectives were fulfilled: (i) A spline-spectral covariance model was developed to enhanced the capability of the innovation method for error covariance estimation. (ii) Non-isotropic error correlation functions were derived for radar radial-wind analysis and used to reformulate the innovation method. The reformulated method provided the first objective way to statistically estimate not only radar observation error variance but also observation error correlation between neighboring gates or beams of radar scans at very fine scales. (iii) By using the advanced functional approach and generalized Fourier transformation, the inverse of a covariance function was shown to be representable by a vector differential operator, called D-operator. With D-operator representations, the inverses error covariance matrices can be formulated directly and efficiently in the cost-functions of variational data assimilation.

Limitations: APPROVED FOR PUBLIC RELEASE
Description: Final technical rept. 15 May 2003-30 Sep 2005
Pages: 5
Report Date: 12 DEC 2005
Contract Number: N000140310822
Report Number: A544144
Keywords relating to this report:
*COVARIANCE
*ERROR ANALYSIS
DIFFERENTIAL EQUATIONS
FOURIER TRANSFORMATION
FUNCTIONS_MATHEMATICS_
MATHEMATICAL PREDICTION
MATRICES_MATHEMATICS_
NUMERICAL ANALYSIS
OPERATORS_MATHEMATICS_
VECTOR ANALYSIS
WEATHER FORECASTING
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