Refinement of the Use of Inhomogeneous Background Error Covariance Estimated from Historical Forecast Error Samples and its Impact on Short-Term Regional Numerical Weather Prediction

[摘要]  Background error covariance (BEC) is one of the key components in data assimilation systems for numerical weather prediction. Recently, a scheme of using an inhomogeneous and anisotropic BEC estimated from historical forecast error samples has been tested by utilizing the extended alpha control variable approach (BEC-CVA) in the framework of the variational Data Assimilation system for the Weather Research and Forecasting model (WRFDA). In this paper, the BEC-CVA approach is further examined by conducting single observation assimilation experiments and continuous-cycling data assimilation and forecasting experiments covering a 3-week period. Additional benefits of using a blending approach (BEC-BLD), which combines a static, homogeneous BEC and an inhomogeneous and anisotropic BEC, are also assessed.

[学科分类] 大气科学

[关键词] numerical weather prediction;data assimilation;background error covariance;inhomogeneous;computational cost