Journal article

Hybrid 4DVAR with a Local Ensemble Tangent Linear Model: Application to the Shallow-Water Model.

DR ALLEN, CH BISHOP, S FROLOV, KW HOPPEL, DD KUHL, GE NEDOLUHA

Monthly Weather Review | American Meteorological Society | Published : 2017

Abstract

An ensemble-based tangent linear model (TLM) is described and tested in data assimilation experiments using a global shallow-water model (SWM). A hybrid variational data assimilation system was developed with a 4D variational (4DVAR) solver that could be run either with a conventional TLM or a local ensemble TLM (LETLM) that propagates analysis corrections using only ensemble statistics. An offline ensemble Kalman filter (EnKF) is used to generate and maintain the ensemble. The LETLM uses data within a local influence volume, similar to the local ensemble transform Kalman filter, to linearly propagate the state variables at the central grid point. After tuning the LETLM with offline 6-h fore..

View full abstract

Grants

Awarded by Office of Naval Research


Funding Acknowledgements

This work was funded by the U.S. Office of Naval Research. Douglas Allen, Karl Hoppel, and Gerald Nedoluha acknowledge support from Office of Naval Research base funding via Task BE-033-02-42. David Kuhl, Karl Hoppel, and Gerald Nedoluha acknowledge support from Office of Naval Research base funding via Task BE-435-050. Sergey Frolov and Craig Bishop acknowledge support from Office of Naval Research Award N0001412WX20323. We thank the editor and two anonymous reviewers for their helpful comments.