TY - GEN
AU - Massimo Bonavita
AU - L. Isaksen
AU - E. Hólm
AB - A hybrid assimilation system which uses sample statistics from an Ensemble of Data Assimilations (EDA) to estimate background error variances has been implemented at ECMWF. We show that the new system is beneficial in terms of deterministic forecast skill provided that random and systematic errors in the estimation of variances are properly accounted for. The mechanisms through which EDA sample variances influence the deterministic analysis are clarified. An interesting aspect is that the use of flow-dependent variances alone is able to introduce a significant degree of flow-dependency in the analysis increments.
BT - ECMWF Technical Memoranda
DA - 01/2012
DO - 10.21957/3msfrh5zm
LA - eng
M1 - 664
N2 - A hybrid assimilation system which uses sample statistics from an Ensemble of Data Assimilations (EDA) to estimate background error variances has been implemented at ECMWF. We show that the new system is beneficial in terms of deterministic forecast skill provided that random and systematic errors in the estimation of variances are properly accounted for. The mechanisms through which EDA sample variances influence the deterministic analysis are clarified. An interesting aspect is that the use of flow-dependent variances alone is able to introduce a significant degree of flow-dependency in the analysis increments.
PB - ECMWF
PY - 2012
EP - 31
T2 - ECMWF Technical Memoranda
TI - On the use of EDA background error variances in the ECMWF 4D-Var
UR - https://www.ecmwf.int/node/8272
ER -