Accession Number : ADA307969

Title :   Estimating Open-Ocean Boundary Conditions: Sensitivity Studies.

Descriptive Note : Doctoral thesis,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Gunson, James R.

PDF Url : ADA307969

Report Date : SEP 1995

Pagination or Media Count : 155

Abstract : The estimation of boundary conditions for an open-ocean model is addressed here. To mimick the SYNOP experiment in the Gulf Stream, a meandering jet is modeled by the nonlinear barotropic vorticity equation. Simulated observations of velocity are taken. Twin experiments are performed using the adjoint method of assimilating data. Various choices of scaling and first guess for the control variables are applied with various observational strategies. A major new result obtained is the successful estimation of the complete set of initial and boundary conditions. Starting from persistence, temporal variations at the boundaries are created that make the interior flow match well the velocity observations. The spread of information from the observations to the boundaries is investigated. The evaluation of the full error covariance matrix for the control variables from the inverse Hessian is investigated along with its dependence upon the degree of nonlinearity in the dynamics. Further major new results here obtained are the availability of off-diagonal covariances, and the calculation of error covariances for all boundary and initial conditions and for interior fields of streamfunction and vorticity. The role of the Hessian matrix is assessed in gauging the sensitivity of the estimated boundary and initial conditions to the observations.

Descriptors :   *BOUNDARIES, *OCEAN MODELS, *GULF STREAM, VELOCITY, DATA BASES, MATHEMATICAL MODELS, ALGORITHMS, UNCERTAINTY, OPTIMIZATION, OCEAN WAVES, TIME DEPENDENCE, MATRICES(MATHEMATICS), THESES, EDDIES(FLUID MECHANICS), VORTICES, ESTIMATES, FINITE DIFFERENCE THEORY, OCEANOGRAPHIC DATA, FLOW FIELDS, ERROR ANALYSIS, BOUNDARY VALUE PROBLEMS, INTERPOLATION, DATA ACQUISITION, NONLINEAR ANALYSIS, COVARIANCE, BAROMETRIC PRESSURE, HYDROGRAPHY, JET FLOW, MARKOV PROCESSES, POISSON EQUATION, OPEN WATER, FOURIER SERIES.

Subject Categories : Physical and Dynamic Oceanography
      Operations Research

Distribution Statement : APPROVED FOR PUBLIC RELEASE