Integrated set updating assimilation method based on deterministic variational disturbance

By uniformly updating the ensemble perturbation and ensemble average under the variational framework, using deterministic variational perturbation method and flow-dependent background error covariance, the problem of insufficient representation of system error and error characteristics in the prior art is solved, and numerical forecasting is improved assimilation and forecast quality.

CN119166984AActive Publication Date: 2024-12-20NANJING UNIV OF INFORMATION SCI & TECH
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Patent Information

Application Number
CN202411669689.7
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-11-21
Publication Date
2024-12-20
Estimated Expiration
2044-11-21

AI Technical Summary

Technical Problem

There are problems in the existing ensemble-variable hybrid assimilation system, such as system error, covariance underestimation, sampling error, dynamic balance dissonance and localization of observation space in the existing ensemble-variable hybrid assimilation system. The traditional hybrid assimilation method is difficult to implement within the variational framework.

Method used

Using an integrated ensemble update method based on deterministic variational perturbation, the ensemble perturbation and ensemble average are updated under a unified variational framework, minimizing the analysis through the deterministic variational set disturbance update function, and using flow-dependent background error coordination Variance relaxation expansion method realizes unified update of background field and its error covariance.

Benefits of technology

It reduces the complexity of system maintenance, enhances the representativeness of ensemble perturbations to the error characteristics of variational frameworks, improves the continuity and balance of analytical variables in traditional solutions, and improves the assimilation and forecasting level of numerical forecasting systems.

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Abstract

The invention discloses an integrated set updating assimilation method based on deterministic variational disturbance. The method comprises the following steps: taking an ensemble forecast field of an initial set member as a background field set to carry out set-variational mixed assimilation updating set averaging; calculating an innovation vector based on forward observation of the initial guess field and the analysis field of the set and forward observation of the set members, taking the average analysis field of the set as the initial guess field, performing minimization analysis by using a set disturbance update function based on deterministic variational disturbance to obtain updated set disturbance, and superposing the updated set disturbance with the updated set average to obtain a set mean value; a set analysis field is obtained; and respectively carrying out deterministic forecasting and ensemble forecasting by taking the updated ensemble average field and the updated ensemble analysis field as initial fields. According to the method, the continuity and balance characteristics of set disturbance and set average variables in mixed assimilation are improved, high-quality flow-dependent background error covariance is provided for transmission of observation information in an assimilation system, and then the data assimilation and numerical weather forecast level is improved.
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Citation Information

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