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SUMMARY:The effects of directional wind shear on orographic gravity-wave b
 reaking - Maria V. Guarino\, University of Reading\, Department of Meteoro
 logy
DTSTART:20170404T130000Z
DTEND:20170404T140000Z
UID:TALK71699@talks.cam.ac.uk
CONTACT:Dr Alexandra Weiss
DESCRIPTION:In the first part of this talk\, orographic gravity-wave break
 ing in flows with directional wind shear is investigated using numerical s
 imulations of idealized\, nearly hydrostatic\, atmospheric flows over an a
 xisymmetric isolated mountain.\nThese simulations\, which use the WRF-ARW 
 atmospheric model\, differ in degree of flow non-linearity and shear inten
 sity. The aim is to diagnose the conditions for mountain wave breaking bas
 ed on large-scale variables (i.e. wind shear and terrain elevation).\nA re
 gime diagram describing the wave breaking behaviour in Richardson number
 –dimensionless mountain height parameter space is presented.\n\nIn the s
 econd part of the talk\, mountain wave turbulence in the presence of direc
 tional wind shear over the Rocky Mountains in Colorado is investigated.  D
 irectional-shear-induced critical levels are studied by taking 2D power sp
 ectra of the magnitude of the horizontal velocity perturbation field. In t
 hese spectra\, a rotation of the most energetic wave modes with the backgr
 ound wind can be found. Such behaviour is consistent with the mechanism le
 ading to wave breaking in directional shear flows.\n\n
LOCATION:British Antarctic Survey\, Room 187
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