High-Order Generalized LorenzN-Cycle Schemes for Semi-Lagrangian Models Employing Second Derivatives in Time
| Autor: | Lance M. Leslie, R. J. Purser |
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| Rok vydání: | 1997 |
| Předmět: | |
| Zdroj: | Monthly Weather Review. 125:1261-1276 |
| ISSN: | 1520-0493 0027-0644 |
| DOI: | 10.1175/1520-0493(1997)125<1261:hoglnc>2.0.co;2 |
| Popis: | Having recently demonstrated that significant enhancement of forecast accuracy in a semi-Lagrangian model results from the application of high-order time integration methods to the second-derivative form of the equations governing the trajectories, the authors here extend the range of available methods by introducing a class of what they call “generalized Lorenz” (GL) schemes. These explicit GL schemes, like Lorenz’s “N-cycle” methods, which inspired them, achieve a high formal accuracy in time for linear systems at an economy of storage that is the theoretical optimum. They are shown to possess robustly stable and consistent semi-implicit modifications that allow the deepest (fastest) gravity waves to be treated implicitly, so that integrations can proceed efficiently with time steps considerably longer than would be possible in an Eulerian framework. Tests of the GL methods are conducted using an ensemble of 360 forecast cases over the Australian region at high spatial resolution, verifying at ... |
| Databáze: | OpenAIRE |
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