Generation Mechanisms of Convectively Forced Internal Gravity Waves and Their Propagation to the Stratosphere

Song, In Sun; Chun, Hye‐Yeong; Lane, Todd P.

doi:10.1175/1520-0469(2003)060<1960:gmocfi>2.0.co;2

Cited by 101 publications

(121 citation statements)

References 43 publications

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“…The majority of the previous work on secondary initiation has been performed using idealized, cloudresolving simulations (e.g Lane and Reeder, 2001;Beres et al, 2002;Song et al, 2003;Lane and Zhang, 2011). There have been only a handful of observed cases that have been studied in an atmospheric model (Piani et al, 2000;Lac et al, 2002;Morcrette et al, 2006;Marsham and Parker, 2006).…”

Section: Secondary Initiation Of Stormsmentioning

confidence: 99%

Impact of soil moisture and convectively generated waves on the initiation of a West African mesoscale convective system

Birch

Parker

O’Leary

et al. 2012

Quart J Royal Meteoro Soc

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A mesoscale convective system (MCS) case study was observed over northeast Mali as part of the African Monsoon Multidisciplinary Analysis (AMMA) on 31 July 2006. Observations of this case suggest that the soil-moisture heterogeneity and atmospheric gravity waves emitted from a 'parent' MCS were important trigger mechanisms for this system. This study uses high-resolution Met Office Unified Model (MetUM) simulations to assess the importance of the synoptic circulation, land-surface and gravity waves in the initiation and development of the MCS. During the early afternoon shallow convection developed over a region of dry soil within a synoptic-scale convergence zone, which was caused by the confluence of the southerly monsoon flow with winds associated with the circulation around the Saharan heat low. Two pronounced waves were emitted from a nearby 'parent' storm and propagated towards the convergence zone. When the second wave reached the location of the shallow convection, deep convection was immediately initiated. Further convective cells developed later in the afternoon over dry soil, many adjacent to strong soil moisture gradients; these aggregated with the main storm, which later developed into the case study MCS. A comparison of model simulations with/without the soil-moisture heterogeneity and gravity waves shows that the synoptic-scale circulation and convergence zones, specified by the atmospheric analysis, were the most important factors for the successful simulation of the MCS. If the location of the initiation of the system is to be forecast accurately, the land-surface, that is, the soil moisture, must be represented adequately. In order to reproduce the timing of the secondary initiation of convection correctly the model must be able to capture gravity waves that are emitted by existing systems.

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Section: Secondary Initiation Of Stormsmentioning

confidence: 99%

Impact of soil moisture and convectively generated waves on the initiation of a West African mesoscale convective system

Birch

Parker

O’Leary

et al. 2012

Quart J Royal Meteoro Soc

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“…Additionally, we multiply the wave amplitudes by 1/2 because the amplitudes may be overestimated by a factor of ∼2 in linear models as compared to non linear models of convection (Song et al, 2003). Therefore, we multiply the GW amplitudes by w pl /2w max prior to ray tracing, e.g., Figure 1a shows the vertical body force used to model the upward surge of air within a single convective plume with no ground reflection, .…”

Section: Convective Plume Geometries and Ground Reflectionmentioning

confidence: 99%

Reconstruction of the gravity wave field from convective plumes via ray tracing

2009

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Abstract. We implement gravity wave (GW) phases into our convective plume and anelastic ray trace models. This allows us to successfully reconstruct the GW velocity, temperature, and density perturbation amplitudes and phases in the Mesosphere-Lower-Thermosphere (MLT) via ray tracing (in real space) those GWs that are excited from a deep convective plume. We find that the ray trace solutions agree very well with the exact, isothermal, zero-wind, Fourier-Laplace solutions in the Boussinesq limit. This comparison also allows us to determine the normalization factor which converts the GW spectral amplitudes to real-space amplitudes in the ray trace model. This normalization factor can then be used for ray tracing GWs through varying temperature and wind profiles. We show that by adding GW reflection off the Earth's surface, the resulting GW spectrum has more power at larger vertical and horizontal wavelengths. We determine the form of the momentum flux and velocity spectra which allows for easy calculation of GW amplitudes in the MLT and thermosphere. Finally, we find that the reconstructed (ray traced) solution for a deep, convective plume with a duration much shorter than the buoyancy period does not equal the Fourier-Laplace Boussinesq solution; this is likely due to errors in the Boussinesq dispersion relation for very high frequency GWs.

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“…It is known that the intrusion of cloud convective plumes into a sheared, stably stratified atmosphere generates gravity waves associated with considerable vertical transport of fluctuation energy and momentum. This phenomenon can frequently be observed for deep convective plumes (tropical thunderstorms) as well as cumulus convection and has been confirmed and investigated by several studies (citations in Song et al, 2003;Beres, 2004). The contribution to the transport of energy and momentum within the atmosphere, both within the troposphere and between troposphere and stratosphere, is significant and therefore parametrized in advanced General Circulation Models (GCMs).…”

Section: Dynamical Effects Of Cbl-induced Fa Waves In Literaturementioning

confidence: 63%

“…In the most simplistic view, convective clouds in a layer with deviating horizontal velocity were considered to form an obstacle that blocks the flow similarly as studied for orographic undulations, which would result in a standing wave relative to the cloud's velocity. These conceptual 'clouds' have therefore been denoted as 'moving mountains' (Song et al, 2003). However, as the vertical momentum of the cloud seems to be in the order of that of the wave, this explanation was modified and cloud convection more realistically considered as a mechanical oscillator, which enforces waves in the stably stratified atmosphere.…”

Section: Dynamical Effects Of Cbl-induced Fa Waves In Literaturementioning

confidence: 99%

“…However, as the vertical momentum of the cloud seems to be in the order of that of the wave, this explanation was modified and cloud convection more realistically considered as a mechanical oscillator, which enforces waves in the stably stratified atmosphere. If the basically vertically moving clouds enter into a surrounding with a different horizontal velocity, the net contributions of the horizontal fluctuation components become significant, which leads to a net transfer of the cloud's kinetic energy and momentum into the wave field (Song et al, 2003).…”

Section: Dynamical Effects Of Cbl-induced Fa Waves In Literaturementioning

confidence: 99%

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Sheared convective boundary layers: turbulence kinetic energy and entrainment dynamics

Schröter

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4. The recent discovery of epigenetic mechanisms has surprised professional biologists more than scientific amateurs.5. The potential impacts on the climate of large scale use of wind-energy gets too little attention.6. To think out of the box is also very useful to get to know the boundaries of the box.7. Various reasons that are supposed to explain the 'Brexit' can ultimately be traced back to the UK's unique geographical situation.8. One does not have to believe in 'Free Will' to have ethical values, to experience a moral impetus or to feel a desire for the Good.Propositions belonging to the thesis, entitled ´Sheared convective boundary layers: turbulence kinetic energy and entrainment dynamics'Joel Schröter

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Generation Mechanisms of Convectively Forced Internal Gravity Waves and Their Propagation to the Stratosphere

Cited by 101 publications

References 43 publications

Impact of soil moisture and convectively generated waves on the initiation of a West African mesoscale convective system

Impact of soil moisture and convectively generated waves on the initiation of a West African mesoscale convective system

Reconstruction of the gravity wave field from convective plumes via ray tracing

Sheared convective boundary layers: turbulence kinetic energy and entrainment dynamics

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