Accession Number:

ADA582904

Title:

Covariance Localization with the Diffusion-Based Correlation Models

Descriptive Note:

Journal article

Corporate Author:

NAVAL RESEARCH LAB STENNIS DETACHMENT STENNIS SPACE CENTER MS OCEANOGRAPHY DIV

Personal Author(s):

• Yaremchuk, Max
• Nechaev, Dmitry

Report Date:

2013-02-01

Pagination or Media Count:

14.0

Abstract:

Improving the performance of ensemble filters applied to models with many state variables requires regularization of the covariance estimates by localizing the impact of observations on state variables. A covariance localization technique based on modeling of the sample covariance with polynomial functions of the diffusion operator DL method is presented. Performance of the technique is compared with the nonadaptive NAL and adaptive AL ensemble localization schemes in the framework of numerical experiments with synthetic covariance matrices in a realistically inhomogeneous setting. It is shown that the DL approach is comparable in accuracy with the AL method when the ensemble size is less than 100. With larger ensembles, the accuracy of the DL approach is limited by the local homogeneity assumption underlying the technique. Computationally, the DL method is comparable with the NAL technique if the ratio of the local decorrelation scale to the grid step is not too large.

Descriptors:

• *CORRELATION TECHNIQUES
• *COVARIANCE
• ACCURACY
• ERROR ANALYSIS
• ESTIMATES
• OPTIMIZATION

Subject Categories:

• Statistics and Probability

Distribution Statement:

APPROVED FOR PUBLIC RELEASE