Document Type
Article
Publication Version
Published Version
Publication Date
2000
Journal or Book Title
Weather and Forecasting
Volume
15
Issue
5
First Page
630
Last Page
637
DOI
10.1175/1520-0434(2000)015<0630:TIOSOO>2.0.CO;2
Abstract
Simulations were performed using the Eta Model with its eta vertical coordinate and stepwise treatment of terrain, and with a substitution of the terrain-following sigma vertical coordinate to investigate the impact of step orography on flow near high mountains. Two different cases were simulated: (i) a downslope windstorm along the Front Range of the Rocky Mountains, and (ii) stably stratified flow blocked by high mountains in Taiwan. Flow separation on the lee side of the mountains, previously shown to occur in idealized two-dimensional Eta simulations, was also apparent in these real data cases, even for the downslope wind event. The step orography resulted in a substantial underestimate of wind speeds to the lee of the Rockies during the windstorm. Near the surface, both the eta and sigma simulations of the Taiwan blocking event were comparable. For both events, the use of step orography resulted in much weaker mountain waves than occurred when the sigma vertical coordinate was used. Localized vertical velocity perturbations associated directly with the step corners were minor for these cases.
Copyright Owner
American Meteorological Society
Copyright Date
2000
Language
en
File Format
application/pdf
Recommended Citation
Gallus, William A. Jr., "The impact of step orography on flow in the Eta Model: Two contrasting examples" (2000). Geological and Atmospheric Sciences Publications. 25.
https://lib.dr.iastate.edu/ge_at_pubs/25
Comments
This article is from Weather and Forecasting 15 (2000): 630, doi: 10.1175/1520-0434(2000)015<0630:TIOSOO>2.0.CO;2. Posted with permission.