@misc{75272,
  author = {E. Kucukkaraca and Mike Fisher},
  title = {Use of analysis ensembles in estimating flow-dependent background error variances},
  abstract = {This paper represents a preliminary investigation into the use of ensembles of analyses to estimate flow-dependent variances of background error. We study small-scale, dynamically-active systems in the mid latitudes (the storms over France during 26-28th December 1999) and in the tropics (Hurricane Isabel, 6-29th September 2003). We demonstrate that the use of ensemble-based estimates of background error variance can improve the analysis of such systems. Although the approach has considerable potential, we note that good analyses of such small-scale systems are unlikely to be produced unless they are adequately resolved both by the main analysis system, and by the members of the analysis ensemble. We believe that a small ensemble of relatively high resolution members may be preferable to a larger ensemble of lower resolution members. We also highlight the tendency of the analysis ensemble to under-estimate the variance of analysis and background error, particularly in dynamically inactive regions. We consider a few simple measures that try to correct this under-estimate, but note that a better understanding (and representation) of the effects of model error, and of the spatial and inter-channel correlation of observation error, is needed before such ad hoc measures can be eliminated.},
  year = {2006},
  journal = {ECMWF Technical Memoranda},
  number = {492},
  pages = {16},
  month = {04/2006},
  publisher = {ECMWF},
  address = {Shinfield Park, Reading},
  url = {https://www.ecmwf.int/node/10563},
  doi = {10.21957/36n2z0p1p},
  language = {eng},
}