Diagnosis and adaptive tuning of observation‐error parameters in a variational assimilation

Quarterly Journal of the Royal Meteorological Society - Tập 127 Số 574 - Trang 1433-1452 - 2001
Gérald Desroziers1, Serguei Ivanov1
1Météo-France, France

Tóm tắt

Abstract

Following the a posteriori diagnosis approach proposed by some authors, a practical computation of the expectation of sub‐parts of the value of a cost function at the minimum is shown to be feasible by using a randomization technique based on a perturbation of observations or background fields. These computations allow the tuning of observation‐error weighting parameters by applying a simple iterative fixed‐point procedure. The procedure is first tested in a simplified variational scheme on a circular domain and then in a similar scheme but with the addition of the vertical coordinate. The relationship between the proposed approach and the Generalized Cross Validation is also shown. A test in the French Action de Recherche Petite Echelle Grande Echelle (ARPEGE) three‐dimensional variational framework with both simulated observations and background fields is finally performed. It shows that a complete description of observation‐error parameters can be retrieved with only a few iterations and, thus, at a reasonable cost.

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Tài liệu tham khảo

10.1175/1520-0493(1993)121<1714:TCPUAB>2.0.CO;2

Bouttier F. Derber J. andFisher M.1997‘The 1997 revision of theJbterm in 3D/4D‐Var’. Technical Report 192 ECMWF Reading UK

Courtier P. Freydier C. Geleyn J.‐F. Rabier F.andRochas M.1991‘The Arpege project at Météo‐France’. Pp.193–193in Proceedings of the ECMWF workshop on numerical methods in atmospheric models 9–13 September 1991 Reading UK

Courtier P., 1987, Variational assimilation of meteorological observations with the adjoint vorticity equation. I: Numerical results, Q. J. R. Meteorol. Soc., 113, 1329, 10.1002/qj.49711347813

10.1002/qj.49712051912

10.1175/1520-0493(1995)123<1128:OLEOEC>2.0.CO;2

Fisher M.1999‘Implementing GCV in the IFS’. Technical Report ECMWF Reading UK

10.1007/BF01589113

Girard D.1987‘A fast Monte Carlo cross‐validation procedure for large least squares problems with noisy data’. Technical Report 687‐M IMAG Grenoble France

10.1214/aos/1176348380

10.1111/j.1600-0870.1986.tb00460.x

10.1111/j.1600-0870.1985.tb00430.x

10.1111/j.1600-0870.1986.tb00461.x

10.1002/qj.49711247414

10.1002/qj.49712455003

10.2151/jmsj1965.75.1B_191

Talagrand O.1999‘A posteriori verification of analysis and assimilation algorithms’. Pp.17–17in Proceedings of the ECMWF Workshop on Diagnosis of data assimilation systems 2–4 November 1999 Reading UK

Thépaut J.‐N. Alary P. Caille P. Cassé V. Geleyn J.‐F. Moll P. Pailleux J. Piriou J.‐M. Puech D.andTaillefer F.1998‘The operational global data assimilation system at Météo‐France’. Pp.25–25in Proceedings of HIRLAM 4 workshop on variational analysis in limited area models Toulouse France

10.1175/1520-0493(1995)123<3358:ATONWP>2.0.CO;2

10.1175/1520-0493(1980)108<1122:SNMMFV>2.0.CO;2

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Quarterly Journal of the Royal Meteorological Society

Tập 127 Số 574

1433-1452

Thông tin tác giả