Vertical Covariance Localization for Satellite Radiances in Ensemble Kalman Filters
William F Campbell, Craig H Bishop, Daniel Hodyss
MONTHLY WEATHER REVIEW | AMER METEOROLOGICAL SOC | Published : 2010
A widely used observation space covariance localization method is shown to adversely affect satellite radiance assimilation in ensemble Kalman filters (EnKFs) when compared to model space covariance localization. The two principal problems are that distance and location are not well defined for integrated measurements, and that neighboring satellite channels typically have broad, overlapping weighting functions, which produce true, nonzero correlations that localization in radiance space can incorrectly eliminate. The limitations of the method are illustrated in a 1D conceptual model, consisting of three vertical levels and a two-channel satellite instrument. A more realistic 1D model is sub..View full abstract
Awarded by National Oceanographic and Aeronautical Administration (NOAA)
Awarded by Office of Naval Research (ONR)
The authors thank Jeff Whitaker, Peter Houtekamer, Herschel Mitchell, and our anonymous reviewer for their valuable comments. We gratefully acknowledge the support of funding from the National Oceanographic and Aeronautical Administration (NOAA), the Office of Naval Research (ONR), and the National Research Council. In particular, support from ONR Project Element 0602435N, Project BE-435-003, ONR Grant N0001407WX30012, and from NOAA, THORPEX Grant NA04AANRG0233 is acknowledged.