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

  1. ELANA J. FERTIG*,
  2. JOHN HARLIM,
  3. BRIAN R. HUNT

Article first published online: 29 NOV 2006

DOI: 10.1111/j.1600-0870.2006.00205.x

Issue

Tellus A

Tellus A

Volume 59, Issue 1, pages 96–100, January 2007

Additional Information

How to Cite

FERTIG, E. J., HARLIM, J. and HUNT, B. R. (2007), A comparative study of 4D-VAR and a 4D Ensemble Kalman Filter: perfect model simulations with Lorenz-96. Tellus A, 59: 96–100. doi: 10.1111/j.1600-0870.2006.00205.x

Author Information

  1. Institute for Physical Science and Technology and Department of Mathematics, University of Maryland, College Park, MD 20742, USA

* *Corresponding author. e-mail: ejfertig@math.umd.edu

Publication History

  1. Issue published online: 29 NOV 2006
  2. Article first published online: 29 NOV 2006
  3. (Manuscript received 7 April 2006; in final form 22 August 2006)

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ABSTRACT

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.

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