scholarly journals Large‐Amplitude Mountain Waves in the Mesosphere Observed on 21 June 2014 During DEEPWAVE: 1. Wave Development, Scales, Momentum Fluxes, and Environmental Sensitivity

2019 ◽  
Vol 124 (19) ◽  
pp. 10364-10384 ◽  
Author(s):  
Michael J. Taylor ◽  
Pierre‐Dominique Pautet ◽  
David C. Fritts ◽  
Bernd Kaifler ◽  
Steven M. Smith ◽  
...  
Keyword(s):  
Large Amplitude ◽  
Environmental Sensitivity ◽  
Mountain Waves ◽  
Momentum Fluxes ◽  
Wave Development

Meteorological Problems in Forecasting Mountain Waves*

1954 ◽  
Vol 35 (8) ◽  
pp. 363-371 ◽  
Author(s):  
DeVer Colson
Keyword(s):  
Static Stability ◽  
Mountain Range ◽  
Mountain Wave ◽  
Mountain Waves ◽  
Wave Development ◽  
Strong Winds ◽  
Wind Shears ◽  
Upper Level ◽  
Meteorological Problems ◽  
Meteorological Phenomenon

The standing-wave development to the lee of prominent mountain ridges presents not only an interesting meteorological phenomenon but also a definite hazard to certain aircraft operations. An analysis of the mountain-wave observations in the Sierras indicates the presence of strong winds normal to the mountain range as well as large vertical wind shears; and an inversion or at least a stable layer near the level of the mountain crest. Changes in the pressure and temperature patterns at both the surface and 500-mb level are shown for two examples of more intense wave developments. Also, mean surface and upper-level pressure and temperature patterns are shown for the strong-wave days. The association between these mean patterns and surface frontal movements, upper-level troughs, strong temperature gradients, and the jet stream are discussed. An example of the effect of wind shear and static stability is shown using equations and methods developed by Scorer. Data on the occurrence of mountain-wave activity in other mountainous areas of the West are now being collected. Two examples of these results are shown.

scholarly journals Large‐Amplitude Mountain Waves in the Mesosphere Observed on 21 June 2014 During DEEPWAVE: 2. Nonlinear Dynamics, Wave Breaking, and Instabilities

2019 ◽  
Vol 124 (17-18) ◽  
pp. 10006-10032 ◽  
Author(s):  
David C. Fritts ◽  
Ling Wang ◽  
Michael J. Taylor ◽  
Pierre‐Dominique Pautet ◽  
Neal R. Criddle ◽  
...  
Keyword(s):  
Nonlinear Dynamics ◽  
Wave Breaking ◽  
Large Amplitude ◽  
Mountain Waves

scholarly journals Observed versus simulated mountain waves over Scandinavia – improvement of vertical winds, energy and momentum fluxes by enhanced model resolution?

2017 ◽  
Vol 17 (6) ◽  
pp. 4031-4052 ◽  
Author(s):  
Johannes Wagner ◽  
Andreas Dörnbrack ◽  
Markus Rapp ◽  
Sonja Gisinger ◽  
Benedikt Ehard ◽  
...  
Keyword(s):  
High Energy ◽  
Horizontal Resolution ◽  
Small Scale ◽  
Mountain Waves ◽  
Stratospheric Intrusion ◽  
Momentum Fluxes ◽  
Wave Effects ◽  
Energy And Momentum ◽  
Vertical Winds ◽  
Mesoscale Simulations

Abstract. Two mountain wave events, which occurred over northern Scandinavia in December 2013 are analysed by means of airborne observations and global and mesoscale numerical simulations with horizontal mesh sizes of 16, 7.2, 2.4 and 0.8 km. During both events westerly cross-mountain flow induced upward-propagating mountain waves with different wave characteristics due to differing atmospheric background conditions. While wave breaking occurred at altitudes between 25 and 30 km during the first event due to weak stratospheric winds, waves propagated to altitudes above 30 km and interfacial waves formed in the troposphere at a stratospheric intrusion layer during the second event. Global and mesoscale simulations with 16 and 7.2 km grid sizes were not able to simulate the amplitudes and wavelengths of the mountain waves correctly due to unresolved mountain peaks. In simulations with 2.4 and 0.8 km horizontal resolution, mountain waves with horizontal wavelengths larger than 15 km were resolved, but exhibited too small amplitudes and too high energy and momentum fluxes. Simulated fluxes could be reduced by either increasing the vertical model grid resolution or by enhancing turbulent diffusion in the model, which is comparable to an improved representation of small-scale nonlinear wave effects.

scholarly journals The Intense Lee-Wave Rotor Event of Sierra Rotors IOP 8

2007 ◽  
Vol 64 (12) ◽  
pp. 4178-4201 ◽  
Author(s):  
Vanda Grubišić ◽  
Brian J. Billings
Keyword(s):  
Sierra Nevada ◽  
Large Amplitude ◽  
Forced Flow ◽  
Mountain Range ◽  
Wave Rotor ◽  
Owens Valley ◽  
Mountain Waves ◽  
Downslope Wind ◽  
Lee Wave ◽  
Strong Control

Abstract A large-amplitude lee-wave rotor event observationally documented during Sierra Rotors Project Intensive Observing Period (IOP) 8 on 24–26 March 2004 in the lee of the southern Sierra Nevada is examined. Mountain waves and rotors occurred over Owens Valley in a pre-cold-frontal environment. In this study, the evolution and structure of the observed and numerically simulated mountain waves and rotors during the event on 25 March, in which the horizontal circulation associated with the rotor was observed as an opposing, easterly flow by the mesonetwork of surface stations in Owens Valley, are analyzed. The high-resolution numerical simulations of this case, performed with the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) run with multiple nested-grid domains, the finest grid having 333-m horizontal spacing, reproduced many of the observed features of this event. These include small-amplitude waves above the Sierra ridge decoupled from thermally forced flow within the valley, and a large-amplitude mountain wave, turbulent rotor, and strong westerlies on the Sierra Nevada lee slopes during the period of the observed surface easterly flow. The sequence of the observed and simulated events shows a pronounced diurnal variation with the maximum wave and rotor activity occurring in the early evening hours during both days of IOP 8. The lee-wave response, and thus indirectly the appearance of lee-wave rotor during the core IOP 8 period, is found to be strongly controlled by temporal changes in the upstream ambient wind and stability profiles. The downstream mountain range exerts strong control over the lee-wave horizontal wavelength during the strongest part of this event, thus exhibiting the control over the cross-valley position of the rotor and the degree of strong downslope wind penetration into the valley.

scholarly journals Sampling Errors in Observed Gravity Wave Momentum Fluxes from Vertical and Tilted Profiles

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 57 ◽  
Author(s):  
Simon B. Vosper ◽  
Andrew N. Ross
Keyword(s):  
Gravity Waves ◽  
Sampling Error ◽  
Numerical Models ◽  
Vertical Profiles ◽  
Sampling Errors ◽  
Mountain Wave ◽  
Mountain Waves ◽  
Momentum Fluxes ◽  
Aircraft Data ◽  
Wave Momentum

Observations from radiosondes or from vertically pointing remote sensing profilers are often used to estimate the vertical flux of momentum due to gravity waves. For planar, monochromatic waves, these vertically integrated fluxes are equal to the phase averaged flux and equivalent to the horizontal averaging used to deduce momentum flux from aircraft data or in numerical models. Using a simple analytical solution for two-dimensional hydrostatic gravity waves over an isolated ridge, it is shown that this equivalence does not hold for mountain waves. For a vertical profile, the vertically integrated flux estimate is proportional to the horizontally integrated flux and decays with increasing distance of the profile location from the mountain. For tilted profiles, such as those obtained from radiosonde ascents, there is a further sampling error that increases as the trajectory extends beyond the localised wave field. The same sampling issues are seen when the effects of the Coriolis force on the gravity waves are taken into account. The conclusion of this work is that caution must be taken when using radiosondes or other vertical profiles to deduce mountain wave momentum fluxes.

scholarly journals A numerical study of mountain waves in the upper troposphere and lower stratosphere

2011 ◽  
Vol 11 (2) ◽  
pp. 4487-4532 ◽  
Author(s):  
A. Mahalov ◽  
M. Moustaoui ◽  
V. Grubišić
Keyword(s):  
Lower Stratosphere ◽  
Numerical Study ◽  
Inversion Layer ◽  
Shear Instability ◽  
Small Scale ◽  
Mountain Waves ◽  
Upper Troposphere ◽  
Microscale Model ◽  
Momentum Fluxes ◽  
Simulation Results

Abstract. A numerical study of mountain waves in the Upper Troposphere and Lower Stratosphere (UTLS) is presented for two Intensive Observational Periods (IOPs) of the Terrain-induced Rotor Experiment (T-REX). The simulations use the Weather Research and Forecasting (WRF) model and a microscale model that is driven by the finest WRF nest. During IOP8, the simulation results reveal presence of perturbations with short wavelengths in zones of strong vertical wind shear in the UTLS that cause a reversal of momentum fluxes. The spectral properties of these perturbations and the attendant vertical profiles of heat and momentum fluxes show strong divergence near the tropopause indicating that they are generated by shear instability along shear lines locally induced by the primary mountain wave originating from the lower troposphere. This is further confirmed by results of an idealized simulation initialized with the temperature and wind profiles obtained from the microscale model. For IOP6, we analyse distributions of O3 and CO observed in aircraft measurements. These show small scale fluctuations with amplitudes and phases that vary along the path of the flight. Comparison between these fluctuations and the observed vertical velocity show that the behavior of these short fluctuations is due not only to the vertical motion, but also to the local mean vertical gradients where the waves evolve, which are modulated by larger variations. The microscale model simulation results shows favorable agreement with in situ radiosonde and aircraft observations. The high vertical resolution offered by the microscale model is found to be critical for resolution of smaller scale processes such as formation of inversion layer associated with trapped lee waves in the troposphere, and propagating mountain waves in the lower stratosphere.

Theory of mountain waves of large amplitude

1959 ◽  
Vol 85 (364) ◽  
pp. 131-143 ◽  
Author(s):  
R. S. Scorer ◽  
H. Klieforth
Keyword(s):  
Large Amplitude ◽  
Mountain Waves

scholarly journals Lidar observations of large-amplitude mountain waves in the stratosphere above Tierra del Fuego, Argentina

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
N. Kaifler ◽  
B. Kaifler ◽  
A. Dörnbrack ◽  
M. Rapp ◽  
J. L. Hormaechea ◽  
...  
Keyword(s):  
Large Amplitude ◽  
Tierra Del Fuego ◽  
Mountain Waves ◽  
Lidar Observations

Estimation of Gravity Wave Momentum Flux and Phase Speeds from Quasi-Lagrangian Stratospheric Balloon Flights. Part II: Results from the Vorcore Campaign in Antarctica

2008 ◽  
Vol 65 (10) ◽  
pp. 3056-3070 ◽  
Author(s):  
Albert Hertzog ◽  
Gillian Boccara ◽  
Robert A. Vincent ◽  
François Vial ◽  
Philippe Cocquerez
Keyword(s):  
Gravity Wave ◽  
Momentum Flux ◽  
General Circulation ◽  
General Circulation Models ◽  
Companion Paper ◽  
Wave Drag ◽  
Mountain Waves ◽  
Long Duration ◽  
Momentum Fluxes ◽  
Wave Momentum

The stratospheric gravity wave field in the Southern Hemisphere is investigated by analyzing observations collected by 27 long-duration balloons that flew between September 2005 and February 2006 over Antarctica and the Southern Ocean. The analysis is based on the methods introduced by Boccara et al. in a companion paper. Special attention is given to deriving information useful to gravity wave drag parameterizations employed in atmospheric general circulation models. The balloon dataset is used to map the geographic variability of gravity wave momentum fluxes in the lower stratosphere. This flux distribution is found to be very heterogeneous with the largest time-averaged value (28 mPa) observed above the Antarctic Peninsula. This value exceeds by a factor of ∼10 the overall mean momentum flux measured during the balloon campaign. Zonal momentum fluxes were predominantly westward, whereas meridional momentum fluxes were equally northward and southward. A local enhancement of southward flux is nevertheless observed above Adélie Land and is attributed to waves generated by katabatic winds, for which the signature is otherwise rather small in the balloon observations. When zonal averages are performed, oceanic momentum fluxes are found to be of similar magnitude to continental values (2.5–3 mPa), stressing the importance of nonorographic gravity waves over oceans. Last, gravity wave intermittency is investigated. Mountain waves appear to be significantly more sporadic than waves observed above the ocean.

scholarly journals Numerical simulation of mountain waves over the southern Andes, Part 2: Momentum fluxes and wave/mean-flow interactions

2021 ◽  
Author(s):  
David C. Fritts ◽  
Thomas S. Lund ◽  
Kam Wan ◽  
Han-Li Liu
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Acoustic Waves ◽  
Large Scale ◽  
Mean Flow ◽  
Mountain Wave ◽  
Southern Andes ◽  
Mountain Waves ◽  
Momentum Fluxes ◽  
Flow Interactions

AbstractA companion paper by Lund et al. (2020) employed a compressible model to describe the evolution of mountain waves arising due to increasing flow with time over the Southern Andes, their breaking, secondary gravity waves and acoustic waves arising from these dynamics, and their local responses. This paper describes the mountain wave, secondary gravity wave, and acoustic wave vertical fluxes of horizontal momentum, and the local and large-scale three-dimensional responses to gravity breaking and wave/mean-flow interactions accompanying this event. Mountain wave and secondary gravity wave momentum fluxes and deposition vary strongly in space and time due to variable large-scale winds and spatially-localized mountain wave and secondary gravity wave responses. Mountain wave instabilities accompanying breaking induce strong, local, largely-zonal forcing. Secondary gravity waves arising from mountain wave breaking also interact strongly with large-scale winds at altitudes above ~80km. Together, these mountain wave and secondary gravity wave interactions reveal systematic gravity-wave/mean-flow interactions having implications for both mean and tidal forcing and feedbacks. Acoustic waves likewise achieve large momentum fluxes, but typically imply significant responses only at much higher altitudes.

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