Abstract
[1] The methodology to generate members of an ensemble is an important issue in operational forecasting; currently a number of procedures are followed at different operational centres. In the present work we propose and evaluate a methodology where a dynamically consistent set of initial conditions is generated through 4D-Var assimilation procedure. The perturbations are generated through 4D-Var assimilation with different information (observation) content, either through a variation in the frequency of observations or a variation in the length of assimilation window. We adopt a representative non-linear system, viz. the three-variable Lorenz system and show that ensemble forecasts generated through 4D-Var assimilation show less error than those generated from initial conditions (with similar amplitude of perturbation) adopted arbitrarily. Another advantage of the procedure is that it provides a (variable-specific) estimate of the maximum allowed amplitude and spread of perturbations.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
