Adaptive Ensemble Covariance Localization in Ensemble 4D-VAR State Estimation
Craig H Bishop, Daniel Hodyss
MONTHLY WEATHER REVIEW | AMER METEOROLOGICAL SOC | Published : 2011
An adaptive ensemble covariance localization technique, previously used in "local" forms of the ensemble Kalman filter, is extended to a global ensemble four-dimensional variational data assimilation (4D-VAR) scheme. The purely adaptive part of the localization matrix considered is given by the element-wise square of the correlation matrix of a smoothed ensemble of streamfunction perturbations. It is found that these purely adaptive localization functions have spurious far-field correlations as large as 0.1 with a 128-member ensemble. To attenuate the spurious features of the purely adaptive localization functions, the authors multiply the adaptive localization functions with very broadscale..View full abstract
Awarded by ONR
CHB and DH gratefully acknowledge financial support from ONR Project Element 0602435N, Project BE-435-003, and ONR Grant N0001407WX30012.