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- Title
Sensitivity of the NCEP Regional Spectral Model to Domain Size and Nesting Strategy.
- Authors
Henry Juang, Hann-Ming; Hong, Song-You
- Abstract
This paper evaluates the performance of the National Centers for Environmental Prediction (NCEP) Regional Spectral Model (RSM) based on the sensitivities of different model domain sizes and horizontal resolutions. The perturbation method and the spectral computation in the NCEP RSM construct the nesting strategy as a “domain nesting” in physical space as well as a “spectral nesting” in spectral space, instead of the conventional “lateral boundary nesting” as used in most regional models. The NCEP RSM has the same model structure, dynamics, and physics as its outer coarse-resolution global model, and it also has a terrain blending along the lateral boundary at the initial time. Both together result in a smooth lateral boundary behavior through one-way nesting. An optimal lateral boundary relaxation reduces the influence of lateral boundary error and generates more areas with small-scale features. The treatment of numerical stabilities, such as a semi-implicit time scheme, time filter, and horizontal diffusion, are applied in perturbation without recomputing or disturbing the large-scale waves. The combination of the aforementioned methods is the uniqueness of the NCEP RSM, which demonstrates the capabilities to conserve the large-scale waves, resolve the mesoscale features, and minimize the lateral boundary errors. A case of winter cyclogenesis with propagation of the synoptic-scale disturbances through the lateral boundaries was selected to investigate the sensitivities of the NCEP RSM based on different nesting strategies. The results from the experiment over a quarter-sphere domain with similar resolutions between RSM and T126 global model demonstrated that the domain nesting was a success, because the lateral boundary error and perturbation were negligibly small. The experiments in a 48-km resolution with different sizes of the model domain had mixed results. The continental domain had the best performance but i...
- Subjects
NATIONAL Centers for Environmental Prediction (U.S.); PERTURBATION theory
- Publication
Monthly Weather Review, 2001, Vol 129, Issue 12, p2904
- ISSN
0027-0644
- Publication type
Article
- DOI
10.1175/1520-0493(2001)129<2904:SOTNRS>2.0.CO;2