Accessibility navigation


The spacing of orographic rainbands triggered by small-scale topography

Kirshbaum, D. J., Rotunno, R. and Bryan, G. H. (2007) The spacing of orographic rainbands triggered by small-scale topography. Journal of the Atmospheric Sciences, 64 (12). pp. 4222-4245. ISSN 1520-0469

Full text not archived in this repository.

To link to this article DOI: 10.1175/2007JAS2335.1

Abstract/Summary

A combination of idealized numerical simulations and analytical theory is used to investigate the spacing between convective orographic rainbands over the Coastal Range of western Oregon. The simulations, which are idealized from an observed banded precipitation event over the Coastal Range, indicate that the atmospheric response to conditionally unstable flow over the mountain ridge depends strongly on the subridge-scale topographic forcing on the windward side of the ridge. When this small-scale terrain contains only a single scale (l) of terrain variability, the band spacing is identical to l, but when a spectrum of terrain scales are simultaneously present, the band spacing ranges between 5 and 10 km, a value that is consistent with observations. Based on the simulations, an inviscid linear model is developed to provide a physical basis for understanding the scale selection of the rainbands. This analytical model, which captures the transition from lee waves upstream of the orographic cloud to moist convection within it, reveals that the spacing of orographic rainbands depends on both the projection of lee-wave energy onto the unstable cap cloud and the growth rate of unstable perturbations within the cloud. The linear model is used in tandem with numerical simulations to determine the sensitivity of the band spacing to a number of environmental and terrain-related parameters.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Science > School of Mathematical and Physical Sciences > Department of Meteorology
ID Code:4642
Uncontrolled Keywords:Orographic effects, Rainbands, Topographic effects
Publisher:American Meteorological Society

Centaur Editors: Update this record

Page navigation