Study and Investigation of Computer Algorithms for the Solution of the Shallow-Fluid Equations as a Means of Computing Terrain Influences on Wind Fields. Appendices A, B, C and D

摘要

This report describes the development and implementation of a computer algorithm, based on the shallow-fluid equations of oceanography, for calculating the wind field above complex terrain. The algorithm contains a two-dimensional shallow-fluid model in the form of a fully-documented computer program compatible with a UNIVAC 1108 machine. To guide the selection of initialization procedures and the optimum finite-differencing scheme applicable to numerical solutions of the algorithm, a detailed study was made of the analytical solution of the shallow-fluid equations for one-dimensional flows over an isolated ridge. The selected optimum finite-differencing procedure is a Lax-Wendroff scheme using nine grid points and two time levels in combination with a nine-point low-pass filter. Comparisons of calculated wind field patterns with recent detailed observations of wind circulations above complex terrain show excellent qualitative agreement in the limited cases available for analysis. Additionally, the computer algorithm for the two-dimensional model, when applied to the terrain at White Sands Missile Range, gave results that were consistent with limited observations available for two example situations. The computer program containing the two-dimensional shallow-fluid model is written in FORTRAN V language and is fully documented in the four appendices to the report. The documentation includes user's instructions, a complete program listing, detailed flow diagrams, and a completely worked example problem.