Assimilation of Geosat altimeter data for the Agulhas current using the ensemble Kalman filter with

Abstract The ring-shedding process in the Agulhas Current is studied using the ensemble Kalman filter to assimilate Geosat altimeter data into a two-layer quasigeostrophic ocean model. The properties of the ensemble Kalman filter are further explored with focus on the analysis scheme and the use of gridded data. The Geosat data consist of 10 fields of gridded sea surface height anomalies separated 10 days apart that are added to a climatic mean field. This corresponds to a huge number of data values, and a data reduction scheme must be applied to increase the efficiency of the analysis procedure. Further, it is illustrated how one can resolve the rank problem occurring when a too large dataset or a small ensemble is used.

[1]  E. Epstein,et al.  Stochastic dynamic prediction , 1969 .

[2]  Thomas A. Gleeson.  Statistical-Dynamical Predictions , 1970 .

[3]  C. Leith.  Atmospheric Predictability and Two-Dimensional Turbulence , 1971 .

[4]  Rex J. Fleming,et al.  ON STOCHASTIC DYNAMIC PREDICTION: I. The Energetics of Uncertainty and the Question of Closure , 1971 .

[5]  Rex J. Fleming,et al.  ON STOCHASTIC DYNAMIC PREDICTION , 1971 .

[6]  E. J. Pitcher,et al.  Stochastic Analysis of Meteorological Fields , 1972 .

[7]  C. Leith.  Theoretical Skill of Monte Carlo Forecasts , 1974 .

[8]  R. Salmon,et al.  The equilibrium statistical mechanics of simple quasi-geostrophic models , 1976, Journal of Fluid Mechanics.

[9]  E. Pitcher.  Application of Stochastic Dynamic Prediction to Real Data , 1977 .

[10]  A. N. Seidman.  Averaging Techniques in Long-Range Weather Forecasting , 1981 .

[11]  J. Lutjeharms,et al.  Characteristics of the currents east and south of Madagascar , 1981 .

[12]  Southern ocean atlas , 1982 .

[13]  W. D. Ruijter.  Asymptotic Analysis of the Agulhas and Brazil Current Systems , 1982 .

[14]  J. Holton.  Geophysical fluid dynamics. , 1983, Science.

[15]  J. Lutjeharms,et al.  Topographic control in the Agulhas Current system , 1984 .

[16]  R. Sætre,et al.  The circulation of the Mozambique channel , 1984 .

[17]  W. D. Ruijter,et al.  The wind-driven circulation in the South Atlantic-Indian Ocean—I. Numerical experiments in a one-layer model , 1985 .

[18]  W. D. Ruijter,et al.  Separation of an Inertial Boundary Current from a Curved Coastline , 1986 .

[19]  Arnold L. Gordon,et al.  Interocean Exchange of Thermocline Water , 1986 .

[20]  The wind-driven circulation of the South Atlantic-Indian ocean — II. Experiments using a multi-layer numerical model , 1986 .

[21]  A. Gordon,et al.  Shedding of an Agulhas ring observed at sea , 1987, Nature.

[22]  E. Chassignet,et al.  Dynamics of Agulhas Retroflection and Ring Formation in a Numerical Model. Part I: The Vorticity Balance , 1988 .

[23]  E. Chassignet,et al.  Dynamics of Agulhas Retroflection and Ring Formation in a Numerical Model. Part II. Energetics and Ring Formation , 1988 .

[24]  W. Budgell,et al.  The Kalman smoother for a linear quasi-geostrophic model of ocean circulation , 1989 .

[25]  A. Gordon,et al.  Agulhas eddies invade the south Atlantic: Evidence From Geosat altimeter and shipboard conductivity‐temperature‐depth survey , 1990 .

[26]  Michael A. Spall,et al.  Regional Primitive Equation Studies of the Gulf Stream Meander and Ring Formation Region , 1990 .

[27]  B. Ambrosius,et al.  Geosat altimeter data analysis for the oceans around South Africa , 1990 .

[28]  W. R. Holland,et al.  Modelled time-dependent flow in the Agulhas retroflection region as deduced from altimeter data assimilation , 1991 .

[29]  G. Evensen.  Using the Extended Kalman Filter with a Multilayer Quasi-Geostrophic Ocean Model , 1992 .

[30]  R. Weiss,et al.  Thermocline and intermediate water communication between the south Atlantic and Indian oceans , 1992 .

[31]  A. Bennett.  Inverse Methods in Physical Oceanography , 1992 .

[32]  P. Brasseur,et al.  Data Assimilation: Tools for Modelling the Ocean in a Global Change Perspective , 1994 .

[33]  M. L. Gründlingh,et al.  Eddy fluxes of heat and salt from the southwest Indian Ocean into the southeast Atlantic Ocean : a case study , 1994 .

[34]  G. Evensen.  Inverse methods and data assimilation in nonlinear ocean models , 1994 .

[35]  G. Evensen.  Sequential data assimilation with a nonlinear quasi‐geostrophic model using Monte Carlo methods to forecast error statistics , 1994 .

[36]  Michael Ghil,et al.  Advanced data assimilation in strongly nonlinear dynamical systems , 1994 .