The Impact of Moisture on Mountain Waves during T-REX

Qingfang Jiang; Doyle, James D.
November 2009
Monthly Weather Review;Nov2009, Vol. 137 Issue 11, p3888
Academic Journal
The impact of moist processes on mountain waves over Sierra Nevada Mountain Range is investigated in this study. Aircraft measurements over Owens Valley obtained during the Terrain-induced Rotor Experiment (T-REX) indicate that mountain waves were generally weaker when the relative humidity maximum near the mountaintop level was above 70%. Four moist cases with a RH maximum near the mountaintop level greater than 90% have been further examined using a mesoscale model and a linear wave model. Two competing mechanisms governing the influence of moisture on mountain waves have been identified. The first mechanism involves low-level moisture that enhances flow–terrain interaction by reducing windward flow blocking. In the second mechanism, the moist airflow tends to damp mountain waves through destratifying the airflow and reducing the buoyancy frequency. The second mechanism dominates in the presence of a deep moist layer in the lower to middle troposphere, and the wave amplitude is significantly reduced associated with a smaller moist buoyancy frequency. With a shallow moist layer and strong low-level flow, the two mechanisms can become comparable in magnitude and largely offset each other.


Related Articles

  • Numerical Consistency of Metric Terms in Terrain-Following Coordinates. Klemp, Joseph B.; Skamarock, William C.; Fuhrer, Oliver // Monthly Weather Review;Jul2003, Vol. 131 Issue 7, p1229 

    In numerically integrating the equations of motion in terrain-following coordinates, care must be taken in treating the metric terms that arise due to the sloping coordinate surfaces. In particular, metric terms that appear in the advection and pressure-gradient operators should be represented...

  • The Role of Upstream Waves and a Downstream Density Pool in the Growth of Lee Waves: Stratified Flow over the Knight Inlet Sill. Klymak, Jody M.; Gregg, Michael C. // Journal of Physical Oceanography;Jul2003, Vol. 33 Issue 7, p1446 

    Observations and modeling simulations are presented that illustrate the importance of a density contrast and the upstream response to the time dependence of stratified flow over the Knight Inlet sill. Repeated sections of velocity and density show that the flow during ebb and flood tides is...

  • Orographic Gravity Waves Close to the Nonhydrostatic Limit of Vertical Propagation. Zängl, Günther // Journal of the Atmospheric Sciences;9/1/2003, Vol. 60 Issue 17, p2045 

    Orographic gravity waves excited by a narrow mountain ridge are investigated with the aid of numerical simulations. When the nondimensional mountain half-width Na/U is around 1—N,a, and U being the Brunt–Väisälä frequency, the dimensional half-width, and the ambient wind...

  • A Simplified Fourier Method for Nonhydrostatic Mountain Waves. Broutman, Dave; Rottman, James W.; Eckermann, Stephen D. // Journal of the Atmospheric Sciences;11/1/2003, Vol. 60 Issue 21, p2686 

    A previously derived approximation to the standard Fourier integral technique for linear mountain waves is extended to include nonhydrostatic effects in a background flow with height-dependent wind and stratification. The approximation involves using ray theory to simplify the vertical...

  • Mountain-Wave Momentum Flux in an Evolving Synoptic-Scale Flow. Chih-Chieh Chen; Durran, Dale R.; Hakim, Gregory J. // Journal of the Atmospheric Sciences;9/1/2005, Vol. 62 Issue 9, p3213 

    The evolution of mountain-wave-induced momentum flux is examined through idealized numerical simulations during the passage of a time-evolving synoptic-scale flow over an isolated 3D mountain of height h. The dynamically consistent synoptic-scale flow U accelerates and decelerates with a period...

  • Large-Amplitude Mountain Wave Breaking over Greenland. Doyle, James D.; Shapiro, Melvyn A.; Qingfang Jiang; Bartels, Diana L. // Journal of the Atmospheric Sciences;9/1/2005, Vol. 62 Issue 9, p3106 

    A large-amplitude mountain wave generated by strong southwesterly flow over southern Greenland was observed during the Fronts and Atlantic Storm-Track Experiment (FASTEX) on 29 January 1997 by the NOAA G-IV research aircraft. Dropwindsondes deployed every 50 km and flight level data depict a...

  • Influence of mountain waves and NAT nucleation mechanisms on polar stratospheric cloud formation at local and synoptic scales during the 1999-2000 Arctic winter. Svendsen, S. H.; Larsen, N.; Knudsen, B.; Eckermann, S. D.; Browell, E. V. // Atmospheric Chemistry & Physics;2005, Vol. 5 Issue 3, p739 

    A scheme for introducing mountain wave-induced temperature pertubations in a microphysical PSC model has been developed. A data set of temperature fluctuations attributable to mountain waves as computed by the Mountain Wave Forecast Model (MWFM-2) has been used for the study. The PSC model has...

  • The Impact of a Prominent Rain Shadow on Flooding in California's Santa Cruz Mountains: A CALJET Case Study and Sensitivity to the ENSO Cycle. Ralph, F. Martin; Neiman, Paul J.; Kingsmill, David E.; Ola, P.; Persson, G.; White, Allen b.; Strem, Eric T.; Andrews, Edmund D.; Antweiler, Ronald C. // Journal of Hydrometeorology;Dec2003, Vol. 4 Issue 6, p1243 

    Data from the California Land-Falling Jets Experiment (CALJET) are used to explore the causes of variations in flood severity in adjacent coastal watersheds within the Santa Cruz Mountains on 2–3 February 1998. While Pescadero Creek (rural) experienced its flood of record, the adjacent...

  • Numerical Study on Vortices in the Middle Layer of Flow around a Large Mountain under Rotating Stratified Conditions. Yu Hozumi; Ueda, Hiromasa // Pure & Applied Geophysics;Oct2005, Vol. 162 Issue 10, p1779 

    Generation of cyclonic vortices in the middle layer of flow around a large mountain like Tibet and Rocky was investigated by means of a 3-D nonhydrostatic meteorological prognostic model. Special attention was paid to the effects of the earth�s rotation and stratification on the vortices...


Read the Article

Courtesy of

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics