Influence of the Valley Surroundings on Valley Wind Dynamics

AMS Citation:
Schmidli, J., and R. Rotunno, 2012: Influence of the Valley Surroundings on Valley Wind Dynamics. Journal of the Atmospheric Sciences, 69, 561-577, doi:10.1175/JAS-D-11-0129.1.
Date:2012-02-01
Resource Type:article
Title:Influence of the Valley Surroundings on Valley Wind Dynamics
Abstract: In a recent study, the authors investigated the mechanisms leading to the formation of diurnal along-valley winds in a valley formed by two isolated mountain ridges on a horizontal plain. The main focus was on the relation between the valley heat budget and the valley-plain pressure difference. The present work investigates the influence of the valley surroundings on the evolution of the valley winds. Three valley-plain configurations with identical valley volumes are studied: a periodic valley, an isolated valley on a plain (the former case), and an isolated valley entrenched in an elevated plateau. According to the valley volume argument (topographic amplification factor), these three cases should develop identical temperature perturbations and thus similar along-valley winds. However, substantial differences are found between the three cases, in particular a much stronger daytime up-valley wind and nighttime down-valley wind for the plateau configuration. The analysis demonstrates the importance of the exchange of along-valley momentum between the valley atmosphere and its surroundings and of the upper-level pressure gradient in explaining the differences among the cases. Furthermore, differences in the upper-level pressure gradient are shown to be related to the heat exchange of the air above the valley atmosphere with the surroundings, which is related to larger-scale cross-valley circulations.
Subject(s):Valley/mountain flows
Peer Review:Refereed
Copyright Information:Copyright 2012 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.
OpenSky citable URL: ark:/85065/d7rv0pcs
Publisher's Version: 10.1175/JAS-D-11-0129.1
Author(s):
  • Juerg Schmidli - NCAR/UCAR
  • Richard Rotunno - NCAR/UCAR
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