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Technical report series on global modeling and data assimilation. volume 16; filtering techniques on a stretched grid general circulation model
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Sawyer, William Takacs, Lawrence L. Fox-Rabinowitz, Michael S. |
| Editor | Suarez, Max J. |
| Copyright Year | 1999 |
| Description | This report documents the techniques used to filter quantities on a stretched grid general circulation model. Standard high-latitude filtering techniques (e.g., using an FFT (Fast Fourier Transformations) to decompose and filter unstable harmonics at selected latitudes) applied on a stretched grid are shown to produce significant distortions of the prognostic state when used to control instabilities near the pole. A new filtering technique is developed which accurately accounts for the non-uniform grid by computing the eigenvectors and eigenfrequencies associated with the stretching. A filter function, constructed to selectively damp those modes whose associated eigenfrequencies exceed some critical value, is used to construct a set of grid-spaced weights which are shown to effectively filter without distortion. Both offline and GCM (General Circulation Model) experiments are shown using the new filtering technique. Finally, a brief examination is also made on the impact of applying the Shapiro filter on the stretched grid. |
| File Size | 3268825 |
| Page Count | 60 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20000010640 |
| Archival Resource Key | ark:/13960/t9x111s22 |
| Language | English |
| Publisher Date | 1999-11-01 |
| Access Restriction | Open |
| Subject Keyword | Geophysics Assimilation Harmonics Stability Fast Fourier Transformations Nonuniformity Atmospheric General Circulation Models Data Integration Finite Difference Theory Geos Satellites Esa Mathematical Models Frequency Response Eigenvectors Spatial Filtering Computational Grids Stretching Polar Regions Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Technical Report |
