Severe downslope windstorms: a nonlinear solution. by David Patrick

Cover of: Severe downslope windstorms: a nonlinear solution. | David Patrick

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Written in English

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  • Physics Theses

Edition Notes

Thesis (M.Sc.), Dept. of Physics, University of Toronto

Book details

ContributionsPeltier, W. R. (supervisor)
The Physical Object
Pagination131 p.
Number of Pages131
ID Numbers
Open LibraryOL20600683M

Download Severe downslope windstorms: a nonlinear solution.

Pulsating Downslope Windstorms. over isolated topography are studied using a two-dimensional nonlinear anelastic model. Long's Stationary Solution and the Evolution toward Severe Downslope.

The Linear Stability of Nonlinear Mountain Waves: Implications for the Understanding of Severe Downslope Windstorms Authors: R.

Laprise. Search for articles by this author Solution of the associatednonseparable boundary value problem reveals an abrupt change in the stability of small amplitude fluctuationswhen the obstacle is Cited by: Colman, B.R.

and C.F. Dierking, On the identification and forecasting of severe downslope windstorms in southeast Alaska. Manuscript in internal review at ERL Boulder. Durran, D.R., Mountain waves and downslope winds. AMS Monograph Atmospheric Processes over Complex Terrain, Chap.

4, (in print). Severe downslope windstorms are a mesoscale, primarily wintertime, phenomenon that affect regions in the lee of large mountain ranges. The resolution of current weather prediction models is too coarse to explicitly predict downslope windstorms.

Hence, additional operational tools are needed for making downslope windstorm by: The results of the laboratory experiments are compared with previous numerical simulations and with a nonlinear hydrostatic theory for severe downslope winds.

DOI: /jtb Severe downslope windstorm occurred during January 11 when the observed wind in the upstream region changed little, a surge of warmer air moved across the northwestern US at hPa, accompanied by rapid pressure falls and strong surface cyclogenesis in the lee of the Rocky Mountains triggered the downslope by: 6.

An identical phenomenon is shown to be characteristic of the high drag regime in severe downslope windstorms simulated in flows characterized by upstream profiles having constant wind and stability. Severe downslope windstorm occurred during January 1 1 1 when the observed wind in the upstream region chang ed little, a surge of w armer air mov ed across the northwest ern US at Severe downslope winds have been observed in mountainous areas throughout the world and have been studied both from a theoretical point of view and based on modelling and observational analyses.

The most intense episodes, referred to as downslope windstorms, derive from a mountain lee-wave amplification and subsequent breaking, bringing cross Cited by: The linear stability of nonlinear mountain waves: Implications for the understanding of severe downslope windstorms.

while the c F finite-amplitude solution (Miles and Huppert ) of the. An identical phenomenon is shown to be characteristic of the high drag regime in severe downslope windstorms simulated in flows characterized by upstream profiles having constant wind and stability.

This newly discovered pulsation phenomenon is therefore a generic property of flows Severe downslope windstorms: a nonlinear solution. book by the breaking of topographically forced internal by: A multi-scale simulation of an extreme downslope windstorm over complex topography J.

Doyle1 and M. Shapiro2 With 16 Figures Received Septem Revised Decem Summary A severe localized windstorm, with near-surface winds >60msÿ1, occurred in an isolated valley within the Alpine mountains (>m) of central Norway on. Laprise and W.R. Peltier, The linear stability of nonlinear mountain waves: Implications for the under- standing of severe downslope windstorms, J.

Atmos. Sei. 46, Severe downslope windstorms: a nonlinear solution. book. Laprise and W.R. Peltier, On the structural characteristics of steady finite-amplitude mountain waves over bell-shaped topography, J. Atmos. Sei. 46, Cited by: 8. Locations of downslope windstorms (hereafter, “windstorms”) occurrence in the Russian Arctic is shown in Fig.

Novaya Zemlya mountain ridge has a huge horizontal scale ( km wide and about km long); the height of the ridge varies from m on the Southern Island to m on the Northern Island with peaks up to m. INHALTSVERZEICHNIS 3 A The Linear Stability of Nonlinear Mountain Waves: Implicati-ons for the Understanding of Severe Downslope Windstorms.

severe downslope windstorms and rotors over the surface, with significant vertical mixing in the upper troposphere and lower stratosphere and in the mesosphere and lower thermosphere. For this, to study GWs is significant.

The governing equations for GWs consist of the non-linear horizontal momentum equations, mass continuity. This chapter is concerned with dynamically-forced atmospheric flow phenomena which occur when the wind encounters mountains.

The range of effects is wide and therefore attention is restricted to arguably the most important phenomena in terms of weather forecasting.

These are mountain waves, rotors, downslope windstorms, gap winds and barrier by: The Yeongdong region, located east of the Taebaek Mountains, South Korea, often experiences severe windstorms in spring, causing a lot of damages, especially when forest fires spread out rapidly by strong winds.

Here, the characteristics and generation mechanisms of the windstorms in the Yeongdong region on 8 April are examined through a high-resolution Weather Research and Forecasting. authors show that strong-to-severe bora is not a typical falling, katabatic-like wind (Yoshino, ; Jurcec, ), but instead,ˇ it belongs to a class of lee-side severe downslope windstorms (e.g.

the Boulder windstorm). Various subtypes of falling wind may still. Severe downslope winds on the lee sides of mountains have been observed frequently around the world.

They may trigger dust storms in the Taklimakan Desert and Gobi Desert (Sun et al., a, b).Several hypotheses have also been proposed to explain these winds, including: (a) hydraulic jump: if the mountain height exceeds a certain threshold, a strong wind can develop along the lee Cited by: 6.

A numerical study on severe downslope windstorms occurred on 5 April at Gangneung and Yangyang, Korea. Asia-Pacific Journal of Atmospheric Sciences, Vol. 46, Issue. 2, p. Asia-Pacific Journal of Atmospheric Sciences, Vol. 46, Issue. 2, p. Under stably stratified atmospheric conditions, standing internal waves are generated when the flow passes over an obstacle such as a mountain.

When the stratification is sufficiently strong, these waves can break, leading to a localised turbulent : O. Eiff, P.

Bonneton. Abstract. In general, convection, refers to the transport of some property by fluid movement, most often with reference to heat such, it is one of the three main processes by which heat is transported: radiation, conduction, and convection.

Meteorologists typically use the term convection to refer to heat transport by the vertical component of the flow associated with by: Scinocca, J. F., & Peltier, W. The instability of Long’s stationary solution and the evolution toward severe downslope windstorm flow. Part I: Nested grid numerical simulations.

Journal of Atmospheric Science, 50(14), – CrossRef Google ScholarCited by: 5. As the mountain height increases, nonlinear effects on the flow are also likely to increase. Numerical models are applied to the simulation of flow over large-amplitude mountains.

These models differ in the formulation of numerical operators, vertical coordinate systems, top and lateral boundary conditions, the evaluation of pressure, and the.

These studies have identified conditions under which wave breaking occurs and have shown that severe downslope windstorms may occur ultimately in response [Lilly, ; Lilly and Kennedy, ; Peltier and Scinocca, ].

The complex density and wind structure of the atmosphere as well as strong topographic forcing both contribute to the Cited by: Critical levels, where the wind vanishes in the atmosphere, are of key importance for gravity wave drag parametrization.

The reflectivity of these levels to mountain waves is investigated here using a combination of high-resolution numerical simulations and insights from linear theory. A methodology is developed for relating the reflection coefficient R of 2D hydrostatic orographic gravity Author: M.

Teixeira, J. Argaín, Xin Xu. Boulder Downslope Windstorm [16] The severe downslope windstorm developed on the lee side of the Front Range of the Rocky Mountains is a well‐studied case both in observations and numerical simulations (e.g., Lilly and Zipser, ; Cited by: Abstract. The basic flow pattern across a long ridge of mountains is determined by the mountain width.

If the ridge is wide enough that the time required for air to cross it is greater than order 1/f (where f is the Coriolis parameter), rotational effects generate a disturbance with large displacements in the horizontal x-y plane.

As the width decreases to less than km, the perturbations. Scinocca, J. & Peltier, W. The instability of Long's stationary solution and the evolution toward severe downslope windstorm flow.

Part I. Nested grid numerical simulation. Cited by:   Scinocca, J.F., and W.R. Peltier, The instability of Long's stationary solution and the evolution towards severe downslope-windstorm flow. Part II: The application of finite-amplitude local wave-activity flow diagnostics. For the present case: h ≈ m, z c ≈ 1 km, N ≈ × 10 − 2 s − 1, and U 0 ≈ 2 m/s resulting in and For cases in which a severe downslope windstorm develops in the presence of a critical layer, there exists a relationship between and [Smith and Sun, ] that in the supporting information is Cited by: Since coming to NCAR inKlemp has conducted theoretical and modeling research to improve the understanding and prediction of severe weather phenomena such as downslope windstorms, tornadic thunderstorms, squall lines, density currents, and internal bores.

A numerical experiment on the Adelaide gully wind of South Australia W. Sha of the high-drag state solution on the mountain height and the critical-level elevation. They severe downslope windstorms, this dynamical instability may represent a strong source of turbu-File Size: 3MB.

A MOUNTAIN WAVE EVENT WEST OF THE COLORADO PARK RANGE. Christopher N. Jones 1*, Jeffery D. Colton 1, Ray McAnelly 2, and Michael P.

Meyers 1 1 National Weather Service, Grand Junction, Colorado 2 Colorado State University, Fort Collins, Colorado. INTRODUCTION. During the overnight hours of April wind gusts to 40 ms-1 occurred west of the Park Range (.

Hydraulic theory explains severe downslope winds as a transition from subcritical (internal Froude number, Fr > 1) to supercritical (Fr a nonlinear regime, downwind of which an abrupt readjustment to ambient, subcritical conditions occurs at some point above the lee slope in the form of a hydraulic jump Cited by: No headers.

Our third example of the application of the Navier-Stokes equations to natural flows is hydrostatic flows over topography. These occur in many natural settings such as downslope windstorms (Figure \(\PageIndex{1}\)b), tidal ocean currents and flow over dams.

similar to those of severe downslope windstorms that often occur in the atmosphere. A typical sequence of events observed in such flows includes the 'breaking' of a forced stationary internal wave induced by the topography, which results in irreversible mix-ing and the formation, through wave-mean flow interaction, of a decelerated mixed.

Experimental results are presented on the lee-wave breaking process which occurs at low Froude numbers when uniform and strongly stratified flow approaches two-dimensional and quasi two-dimensional Gaussian-shaped obstacles. It was found that the lee-wave breaking process is essentially independent of the two-dimensional and the quasi two-dimensional shape of the by: The validity of linear theory for describing downslope windstorms was investigated by Durran (,).

Using a non-linear non-hydrostatic numerical model, Durran () found that linear theory is better suited for describing the flow characteristics in single layer atmospheres. The momentum transport by gravity waves is of great importance to the atmospheric circulation, structure and variability, especially in the middle atmosphere.

Gravity waves are also closely related to various severe weather phenomena, such as downslope windstorms, orographic .What makes his stature as a geophysicist even more remarkable and impressive is his impact on atmospheric science as well, where he has made profound contributions to problems involving nonlinear processes, including the theory of severe downslope windstorms, the theory of the onset and maturation of density stratified turbulence, and the.

Downslope windstorms occur not only on Earth but are also believed to occur in Martian craters (Magalhaes and Young ). The large number of impact craters on Mars and their possible impact on dust transport and deposition has led to a number of studies on flow over craters (Greeley et al.

; Rafkin et al. ), including simulations for Earth's atmosphere (Soontiens et al. ).

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