Search from over 60,000 research works

Advanced Search

Mountain wave turbulence in the presence of directional wind shear over the Rocky Mountains

[thumbnail of jas-d-17-0128.1.pdf]
Preview
jas-d-17-0128.1.pdf - Accepted Version (9MB) | Preview
[thumbnail of jas-d-17-0128.1.pdf]
Preview
jas-d-17-0128.1.pdf - Published Version (3MB) | Preview
Add to AnyAdd to TwitterAdd to FacebookAdd to LinkedinAdd to PinterestAdd to Email

Guarino, M. V., Teixeira, M. A. C. orcid id iconORCID: https://orcid.org/0000-0003-1205-3233, Keller, T. L. and Sharman, R. D. (2018) Mountain wave turbulence in the presence of directional wind shear over the Rocky Mountains. Journal of the Atmospheric Sciences, 75 (4). pp. 1285-1305. ISSN 1520-0469 doi: 10.1175/JAS-D-17-0128.1

Abstract/Summary

Mountain wave turbulence in the presence of directional wind shear over the Rocky Mountains in Colorado is investigated. Pilot Reports (PIREPs) are used to select cases in which moderate or severe turbulence encounters were reported in combination with significant directional wind shear in the upstream sounding from Grand Junction, CO (GJT). For a selected case, semi-idealized numerical simulations are carried out using the WRF-ARW atmospheric model, initialized with the GJT atmospheric sounding and a realistic but truncated orography profile. In order to isolate the role of directional wind shear in causing wave breaking, sensitivity tests are performed to exclude the variation of the atmospheric stability with height, the speed shear, and the mountain amplitude as dominant wave breaking mechanisms. Significant downwind transport of instabilities is detected in horizontal flow cross-sections, resulting in mountain-wave-induced turbulence occurring at large horizontal distances from the first wave breaking point (and from the orography that generates the waves). The existence of an asymptotic wake, as predicted by Shutts for directional shear flows, is hypothesized to be responsible for this downwind transport. Critical levels induced by directional wind shear are further studied by taking 2D power spectra of the magnitude of the horizontal velocity perturbation field. In these spectra, a rotation of the most energetic wave modes with the background wind, as well as perpendicularity between the background wind vector and the wave-number vector of those modes at critical levels, can be found, which is consistent with the mechanism expected to lead to wave breaking in directional shear flows.

Altmetric Badge

Item Type Article
URI https://reading-clone.eprints-hosting.org/id/eprint/75677
Item Type Article
Refereed Yes
Divisions Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology
Uncontrolled Keywords Flow over orography, Mountain waves, Gravity waves, Wave breaking, Directional shear, Critical levels, Clear-air turbulence
Publisher American Meteorological Society
Download/View statistics View download statistics for this item

Downloads

Downloads per month over past year

University Staff: Request a correction | Centaur Editors: Update this record

Search Google Scholar