Journal article

Flow-adaptive moderation of spurious ensemble correlations and its use in ensemble-based data assimilation

Craig H Bishop, Daniel Hodyss

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY | WILEY | Published : 2007

Abstract

Many ensemble Kalman filter (EnKF) data assimilation (DA) schemes reduce the effect of spurious ensemble correlations caused by small ensemble size by multiplying the correlations by moderation functions. Moderation functions envelop true error correlation functions. Ideal moderation functions would adapt to variations in the movement and width of true error correlation functions. Here, we describe a new method in which flow-dependent moderation functions are built from powers of smoothed ensemble correlations. The approach imparts to the moderation function movement and width information retained by the smoothed ensemble correlations. Spurious smoothed ensemble correlations are attenuated b..

View full abstract

University of Melbourne Researchers