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Obstacles and Benefits of the Implementation of a Reduced Rank Smoother with a High Resolution Model of the Atlantic Ocean : Volume 9, Issue 2 (20/03/2012)

By Freychet, N.

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Book Id: WPLBN0003978439
Format Type: PDF Article :
File Size: Pages 43
Reproduction Date: 2015

Title: Obstacles and Benefits of the Implementation of a Reduced Rank Smoother with a High Resolution Model of the Atlantic Ocean : Volume 9, Issue 2 (20/03/2012)  
Author: Freychet, N.
Volume: Vol. 9, Issue 2
Language: English
Subject: Science, Ocean, Science
Collections: Periodicals: Journal and Magazine Collection, Copernicus GmbH
Publication Date:
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications


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Brankart, J., Cosme, E., Brasseur, P., Freychet, N., & Kpemlie, E. (2012). Obstacles and Benefits of the Implementation of a Reduced Rank Smoother with a High Resolution Model of the Atlantic Ocean : Volume 9, Issue 2 (20/03/2012). Retrieved from

Description: Université Joseph Fourier – Grenoble 1, LEGI, Grenoble, France. Most of oceanographic operational centers use three-dimensional data assimilation schemes to produce reanalyses. We investigate here the benefits of a smoother, i.e. a four-dimensional formulation of statistical assimilation. A square-root sequential smoother is implemented with a tropical Atlantic ocean circulation model. A simple twin experiment is performed to investigate its benefits, compared to its corresponding filter. Results show that the smoother leads to a better estimation of the ocean state, both on statistical (i.e. mean error level) and dynamical point of view. Smoothed states are more in phase with the dynamics of the reference state, an aspect that is nicely illustrated with the chaotic dynamics of the north-Brazil rings. We also show that the smoother efficiency is strongly related to the filter configuration. One of the main obstacles to implement the smoother is then to accurately estimate the error covariances of the filter. Considering this, benefits of the smoother are also investigated with a configuration close to situations that can be managed by operational centers systems, where covariances matrices are fixed (optimal interpolation). We define here a simplified smoother scheme, called half-fixed basis smoother, that could be implemented with current reanalysis schemes. Its main assumption is to neglect the propagation of the error covariances matrix, what leads to strongly reduce the cost of assimilation. Results illustrate the ability of this smoother to provide a solution more consistent with the dynamics, compared to the filter. The smoother is also able to produce analyses independently of the observation frequency, so the smoothed solution appears more continuous in time, especially in case of a low frenquency observation network.

Obstacles and benefits of the implementation of a reduced rank smoother with a high resolution model of the Atlantic ocean

Houtekamer, P. L., Mitchell, H. L., and Deng, X.: Model error representation in an operational Ensemble Kalman Filter, Mon. Weather Rev., 137, 2126–2143, 2009.; Allen, M. R., Lawrence, S. P., Murray, M. J., Mutlow, C. T., Stockdale, T. N., Llewellynjones, D. T., and Anderson, D. L. T.: Control of tropical instability waves in the pacific, Geophys. Res. Lett, 22 , 2581–2584, 1995.; Anderson, B. D. O. and Moore, J. B.: Optimal Filtering, Prentice-Hall, 357pp., 1979.; Brankart, J.-M., Testut, C.-E., Brasseur, P., and Verron, J.: Implementation of a multivariate data assimilation scheme for isopynic coordinate ocean models: application to a 1993–96 hindcast of the North Atlantic Ocean circulation, J. Geophys. Res., 108, 1–20, 2003.; Brankart, J.-M., Ubelmann, C., Testut, C.-E., Cosme, E., Brasseur, P., and Verron, J.: Efficient parameterization of the observation error covariance matrix for square root or ensemble Kalman filters: application to ocean altimetry, Mon. Weather Rev., 137, 1908–1927, 2009.; Brankart, J.-M., Cosme, E., Testut, C.-E., Brasseur, P., and Verron, J.: Efficient adaptative error parametrizations for square root or ensemble Kalman filters: application to the control of ocean mesoscale signals, Mon. Weather Rev., 138, 932–950, 2010.; Brankart, J.-M., Cosme, E., Testut, C.-E., Brasseur, P., and Verron, J.: Efficient local error parameterizations for square root or ensemble Kalman filters: application to a basin-scale ocean turbulent flow, Mon. Weather Rev., 139, 474–493, 2011; Brasseur, P., Bahurel, P., Bertino, L., Birol F., Brankart, J.-M., Ferry, N., Losa, S., Remy, E., Schröter, J., Skachko, S., Testut, C.-E., Tranchant, B., Van Leeuwen, P.J. and Verron, J.: Data Assimilation for marine monitoring and prediction: The MERCATOR operational assimilation systems and the MERSEA developments, Q. J. R. Met. Soc., 131, 3561–3582, 2005.; Brasseur, P. and Verron, J.: The SEEK filter method for data assimilation in oceanography: a synthesis, Ocean Dynam., 56, 650–661, doi:10.1007/s10236-006-0080-3, 2006.; Brodeau, L., Barnier, B., Penduff, T., Treguier, A.-M., and Gulev, S.: An ERA-40 based atmospheric forcing for global ocean circulation models, Ocean Model., 31, 88–104, 2010.; Castruccio, F., Verron, J., Gourdeau, L., Brankart, J.-M., and Brasseur, P.: On the role of the GRACE mission in the joint assimilation of altimetry and TAO data in a tropical Pacific ocean model, Geophys. Res. Lett., 33, L14616, doi:10.1029/2006GL025823, 2006.; Cohn, S. E., Sivakumaran, N. S., and Todling, R.: A fixed-lag Kalman smoother for retrospective data assimilation, Mon. Weather Rev., 122, 2838–2867, 1994.; Houtekamer, P. L. and Mitchell, H. L.: Data assimilation using an Ensemble Kalman Filter technique, Mon. Weather Rev., 126, 796–811, 1998.; Cosme, E., Brankart, J.-M., Verron, J., Brasseur, P., and Krysta, M.: Implementation of a reduced rank square-root smoother for high resolution ocean data assimilation, Ocean Model., 33, 87–100, 2010.; Cosme, E., Verron, J., Brasseur, P., Blum, J., and Auroux, D.: Smoothing problems in a Bayesian framework and their linear Gaussian solutions, Mon. Weather Rev., 140, 683–695, 2011.; Dussin, R., Treguier, A.-M., Molines, J., Barnier, B., Penduff, T., Brodeau, L., and Madec, G.: Definition of the interannual experiment orca025-b83, Tech. rep., 2009.; Evensen, G.: Sequential data assimilation with a non linear quasigeostrophic model using monte carlo methods to forecast error statistics, J. Geophys. Res., 99, 10143–10162, 1994.; Evensen, G.: The Ensemble Kalman Filter: theoretical formulation and practical implementation, Ocean Dynam., 53, 343–367, doi:10.1007/s10236-003-0036-9, 2003.; Evensen, G.: Data assimilation, The Ensemble Kalman Filter, Springer, 2007.; Evensen, G. and van Leeuwen, P. J.: An en


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