TY - CPAPER AU - L. Isaksen AU - Mike Fisher AU - J. Berner BT - ECMWF Workshop on Flow-dependent aspecyts of data assimilation, 11-13 June 2007 CY - Shinfield Park, Reading DA - 2007 LA - eng PB - ECMWF PP - Shinfield Park, Reading PY - 2007 SP - 65 EP - 86 T2 - ECMWF Workshop on Flow-dependent aspecyts of data assimilation, 11-13 June 2007 TI - Use of analysis ensembles in estimating flow-dependent background error variance ER -