DSC Publications

Core Information
Title: Different approaches to model error formulation in 4D-Var: a study with high-resolution advection schemes
Abstract: All numerical models are imperfect. Weak constraint variational data assimilation (VDA), which provides a treatment of the modelling errors, is studied; building on the approach of Vidard et al. (Tellus, 56A, pp. 177–188, 2004). The evolution of model error (ME) is modelled using ordinary differential equations, which involve a scalar parameter. These approaches were tested using different high-resolution advection schemes. The first set of experiments were constructed to see if it is possible to account for (numerical) discretization error within such a framework. In other set of experiments, a systematic source of modelling error was introduced by deliberately specifying an incorrect value for the Coriolis parameter in the model. Results with observational state at half of the model state resolution, are also presented.We also discuss a method of estimating the scalar parameter in the ME through VDA. In all cases, the inclusion of ME provides reduction in forecasting errors. Also, our experiments indicate that different settings of the model (e.g. using different high-resolution advection schemes) would need different ME formulation. Results presented in this paper could be used to formulate sophisticated ME forms to account for systematic errors in higher dimensional models with complex advection schemes
Keywords: model error in 4-D VAR, high resolution advection schemes, parameter estimation,shallow water finite volume model
Author Information
1. Akella, Santha[ Department of Earth & Planetary Sciences, The Johns Hopkins University, Baltimore, MD 21218, USA ]Post doc
2. Navon, Ionel M[ FSU/SCS ]Neither
Detailed Scientific Article Information
Journal Name: Tellus Series A: Dynamic Meterology and Oceanography
Volume: Vol 61A,
Page Range: 112-128
Article Number: Not Provided
Number of Pages: 18
Year of Publication: 2009
Refereed: Yes
Digital Object Identifier (DOI), if available: 10.1111/j.1600-0870.2008.00362.x
Official Url: http://www3.interscience.wiley.com/journal/119879027/issue
ISSN: 0280-6495
Subjects Information
1. Meteorology
2. Mathematics
3. Fluid Dynamics

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