A method of setting up finite-difference schemes for prediction equations /

The paper presents two types of finite-difference schemes to represent the barotropic vorticity equation as an analogy to the principle of conservation of vorticity. The first type is conservative with respect to integration and can be separated into an explicit component which is conditionally stable and an implicit component which is unconditionally stable. The other type is equivalent to a quasi-Lagrangian model and is an explicit scheme which is entirely unconditionally stable. However, when necessary, the time-step in an unconditionally stable scheme may be extended to meet operational requirements. The evaluation of the wind field and the related problems on smoothing are discussed in relation to the computational requirements of each scheme. The discussion includes specifications of boundary and initial conditions. The numerical results given by the explicit forms are assessed by means of actual predictions and the evaluation of idealized fields.Translation supported by the Air Force Cambridge Research Laboratories, Office of Aerospace Research, United States Air Force (L.G. Hanscom Field, Mass.), and translated by the Oriental Science Research Library of Emmanuel College, Boston, Massachusetts, under Contract F19628-68-C-0251.Translated from Acta Meteorologica Sinica, v. 35, n. 4, pp. 399-407, 1965.AFCRL Research Library.AD0686200 (from http://www.dtic.mil)."March 1969."Includes bibliographical references (page 15).The paper presents two types of finite-difference schemes to represent the barotropic vorticity equation as an analogy to the principle of conservation of vorticity. The first type is conservative with respect to integration and can be separated into an explicit component which is conditionally stable and an implicit component which is unconditionally stable. The other type is equivalent to a quasi-Lagrangian model and is an explicit scheme which is entirely unconditionally stable. However, when necessary, the time-step in an unconditionally stable scheme may be extended to meet operational requirements. The evaluation of the wind field and the related problems on smoothing are discussed in relation to the computational requirements of each scheme. The discussion includes specifications of boundary and initial conditions. The numerical results given by the explicit forms are assessed by means of actual predictions and the evaluation of idealized fields.Mode of access: Internet