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RISAn Examination of Alternative Extrapolations to Find the Departure Point Position in a “Two-Time-Level” Semi-Lagrangian Integration
Publisher: American Meteorological Society
Abstract: An unmeteorological oscillation in the forecast fields produced by a two-time-level semi-Lagrangian and semi-implicit model has been traced to the method used for finding the departure point position. Various alternatives ...
Boundary Conditions for Semi-Lagrangian Schemes: Testing Some Alternatives in One-Dimensional Models
Publisher: American Meteorological Society
Abstract: The one-dimensional advection equation and the one-dimensional advection adjustment equation with rotation are used as test beds for the design of well-posed boundary conditions for the initial-boundary-value problem using ...
Transparent Boundary Conditions for the Shallow-Water Equations: Testing in a Nested Environment
Publisher: American Meteorological Society
Abstract: Most operational numerical weather prediction models update their lateral boundaries via the Davies?Kållberg relaxation scheme. In this paper some potential alternatives that take transparency and well-posedness into ...
Accuracy of Multiply-Upstream, Semi-Lagrangian Advective Schemes
Publisher: American Meteorological Society
Abstract: The stability and accuracy of the multiply-upstream, semi-Lagrangian method of integrating the advective equation in two dimensions is examined for four different interpolation schemes; namely, bilinear, biquadratic, bicubic ...
A Semi-Lagrangian and Semi-Implicit Two Time-Level Integration Scheme
Publisher: American Meteorological Society
Abstract: A semi-Lagrangian and semi-implicit two time-level integration scheme has been constructed for integrating the primitive meteorological equations. It can be thought of as working in the following way. During the first ...
Accuracy of Multiply-Upstream Semi-Lagrangian Advective Schemes II
Publisher: American Meteorological Society
Abstract: The degree of accuracy of various multiply-upstream semi-Lagrangian schemes is examined by analyzing the driven one-dimensional advection equation. The relationship between the order of accuracy of a given scheme and the ...
A Step toward Transparent Boundary Conditions for Meteorological Models
Publisher: American Meteorological Society
Abstract: Transparent boundary conditions for the linearized shallow water equations are constructed by incorporating the boundary conditions into equations that describe unidirectional waves. The shallow water equations are then ...
A Two-Time-Level, Three-Dimensional Semi-Lagrangian, Semi-implicit, Limited-Area Gridpoint Model of the Primitive Equations
Publisher: American Meteorological Society
Abstract: A two-time-level, three-dimensional semi-Lagrangian, semi-implicit primitive equation gridpoint model that incorporates a sophisticated physics package is presented. It is shown to give accurate 24-h forecasts when integrated ...
A Comparison of the HIRLAM Gridpoint and Spectral Semi-Lagrangian Models
Publisher: American Meteorological Society
Abstract: A comparison of two semi-Lagrangian limited area models, one spectral, and the other grid point, is described. Forecasts from both models are compared and contrasted, first on a 55-km horizontal mesh and subsequently on a ...
A Two Time-Level, Three-Dimensional, Semi-Lagrangian, Semi-implicit, Limited-Area Gridpoint Model of the Primitive Equations. Part II: Extension to Hybrid Vertical Coordinates
Publisher: American Meteorological Society
Abstract: A two time-level, three-dimensional, semi-Lagrangian semi-implicit primitive equation gridpoint model that incorporates a sophisticated physics package and uses hybrid coordinates in the vertical is derived. A simple filter, ...