A comparative study of 4D-VAR and a 4D Ensemble Kalman Filter: perfect model simulations with Lorenz-96

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Fertig, Elana J. ; Harlim, John ; Hunt, Brian R. (2007)

We formulate a four-dimensional Ensemble Kalman Filter (4D-LETKF) that minimizes a cost function similar to that in a 4D-VAR method. Using perfect model experiments with the Lorenz-96 model, we compare assimilation of simulated asynchronous observations with 4D-VAR and 4D-LETKF. We find that both schemes have comparable error when 4D-LETKF is performed sufficiently frequently and when 4D-VAR is performed over a sufficiently long analysis time window. We explore how the error depends on the time between analyses for 4D-LETKF and the analysis time window for 4D-VAR.
  • References (26)
    26 references, page 1 of 3

    Anderson, J. L. 2001. An ensemble adjustment Kalman filter for data assimilation. Mon. Wea. Rev. 129, 2884-2903.

    Bishop, C. H., Etherton, B. and Majumdar, S. J. 2001. Adaptive sampling with the ensemble transform Kalman filter. Part I: Theoretical aspects. Mon. Wea. Rev. 129, 420-436.

    Burgers, G., van Leeuwen, P. J. and Evensen, G. 1998. Analysis scheme in the ensemble Kalman filter. Mon. Wea. Rev. 126, 1719-1724.

    Courtier, P., TheĀ“paut, J. N. and Hollingsworth, A. 1994. A strategy for operational implementation of 4D-VAR, using an incremental approach. Quart. J. R. Meteorol. Soc. 120, 1367-1387.

    Evensen, G. 1994. Sequential data assimilation with a non-linear quasigeostropic model using Monte Carlo Methods to forecast error statistics. J. Geophys. Res. 99, 10143-10162.

    Evensen, G. and van Leeuwen, P. J. 2000. An ensemble Kalman smoother for nonlinear dynamics. Mon. Wea. Rev. 128, 1852-1867.

    Houtekamer, P. L. and Mitchell, H. L. 1998. Data assimilation using an ensemble Kalman filter technique. Mon. Wea. Rev. 126, 796-811.

    Houtekamer, P. L., Mitchell, H. L., Pellerin, G., Buehner, M., Charron, M, et al. 2005. Atmospheric data assimilation with the ensemble Kalman filter: Results with real observations. Mon. Wea. Rev. 133, 604-620.

    Houtekamer, P. L. and Mitchell, H. L. 2006. Ensemble Kalman Filtering. Quart. J. R. Meteorol. Soc., in press.

    Hunt, B. R., Kalnay, E., Kostelich, E. J., Ott, E., Patil, D. J. and co-authors. 2004. Four-dimensional ensemble Kalman filtering. Tellus 56A, 273-277.

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