It has been suggested (Lindzen, 1967, 1968a, b; Lindzen and Blake, 1971; Hodges, 1969) that turbulence in the upper mesosphere arises from the unstable breakdown of tides and gravity waves. Crudely speaking, it was expected that sufficient turbulence would be generated to prevent the growth of wave amplitude with height (roughly as (basic pressure)−1/2). This work has been extended to allow for the generation of turbulence by smaller amplitude waves, the effects of mean winds on the waves, and the effects of the waves on the mean momentum budget. The effects of mean winds, while of relatively small importance for tides, are crucial for internal gravity waves originating in the troposphere. Winds in the troposphere and stratosphere sharply limit the phase speeds of waves capable of reaching the upper mesosphere. In addition, the existence of critical levels in the mesosphere significantly limits the ability of gravity waves to generate turbulence, while the breakdown of gravity waves contributes to the development of critical levels. The results of the present study suggest that at middle latitudes in winter, eddy coefficients may peak at relatively low altitudes (50 km) and at higher altitudes in summer and during sudden warmings (70–80 km), and decrease with height rather sharply above these levels. Rocket observations are used to estimate momentum deposition by gravity waves. Accelerations of about 100 m/s/day are suggested. Such accelerations are entirely capable of producing the warm winter and cold summer mesopauses.

http://climateknowledge.org/figures/Rood_Climate_Change_AOSS480_Documents/QC114_Lindzen_Gravity_Wave_Stress_JGR_1981.pdf

Turbulence and stress owing to gravity wave and tidal breakdown

A comprehensive review of zonal flow phenomena in plasmas is presented. While the emphasis is on zonal flows in laboratory plasmas, planetary zonal flows are discussed as well. The review presents the status of theory, numerical simulation and experiments relevant to zonal flows. The emphasis is on developing an integrated understanding of the dynamics of drift wave–zonal flow turbulence by combining detailed studies of the generation of zonal flows by drift waves, the back-interaction of zonal flows on the drift waves, and the various feedback loops by which the system regulates and organizes itself. The implications of zonal flow phenomena for confinement in, and the phenomena of fusion devices are discussed. Special attention is given to the comparison of experiment with theory and to identifying directions for progress in future research.

/pdf/zonal-flows-in-plasma-a-review-3byloag115.pdf

Zonal flows in plasma—a review

Review and intercomparison of operational methods for the determination of the mixing height

This report has been prepared as part of an effort by IUCN to define its position on Nature-based Solutions (NbS) and plan for future work to advance this concept and support effective implementation of NbS to enhance ecosystem services provision and address societal challenges. The report proposes a definitional framework for NbS, including a set of general principles for any NbS intervention. The report also defines the scope of NbS as an umbrella concept embracing a number of different ecosystem-based approaches.

/pdf/nature-based-solutions-to-address-global-societal-challenges-1oepeqve5i.pdf

Nature-based solutions to address global societal challenges

A review of theoretical and observational results describing atmospheric gravity wave (AGW)/traveling ionospheric disturbance (TID) phenomena at high latitudes is presented. Some recent experimental studies of AGW's using the Chatanika incoherent scatter radar and other geophysical sensors are reported. Specifically, the following features are described in detail: (1) cause/effect relations between aurorally generated AGW's and TID's detected at mid-latitudes, including probable ‘source signature’ identification, (2) AGW source phenomenology, particularly a semiquantitative assessment of the relative importance of Joule heating, Lorentz forces, intense particle precipitation, and other mechanisms in generating AGW's, and (3) detection of TID's in the auroral ionosphere. Several instances of F region electron density, temperature, and plasma periodicities accompanied by horizontal plasma velocities which were consistent with theoretical AGW/TID models are documented.

Atmospheric gravity waves generated in the high‐latitude ionosphere: A review

Note: Bibliogr. : p. 423-440. Index Reference Record created on 2004-09-07, modified on 2016-08-08

Waves in the atmosphere

Ionospheric irregularities produced by internal atmospheric gravity waves

Development in Atmospheric Science, 2
In recent years 'here has been increased
interest in mesoscale atmospheric waves as
newly developed atmospheric probes such as
radars and acoustic echo sounders have
made it possible to study these waves in
great detail. Numerous observations reported
in a rapidly expending literature on the
subject have demonstrated that these waves
are more than mere curiosities; in fact, they
can play an essential role in the generation of
some kinds of clear air turbulence (CAT), .
thus Creating a hazard to commercial aircraft;,
and they may be very important to the very
dynamics of the larger-scale atmospheric
circulation, This timely book provides the
interested meteorologist, radiophysicist. and
graduate student with a self-contained
introduction to the theory of propagation and
the dynamics of mesoscale atmospheric
waves.

Waves in the atmosphere : atmospheric infrasound and gravity waves : their generation and propagation

The F2 region ionospheric response to individual internal gravity waves is calculated as a function of the azimuth of wave propagation. This response is shown to be highly anisotropic, with the anisotropy itself depending on the wave parameters, the geomagnetic dip, and the prevailing ionization density gradient. Because the ionization density gradient changes with time of day and season, the ionospheric response and hence the traveling ionospheric disturbance statistics themselves should exhibit corresponding diurnal and seasonal variations. The physical basis for the anisotropy of the ionospheric response is discussed.

The ionospheric response to internal gravity waves: 1. The F2 region response

Three in-situ and five remote sensing techniques for measuring the height of the daytime convective boundary layer were compared. There was, as a rule, good agreement between the different systems when the capping inversion was steep and well defined, and some variability when the stratification was not so sharply defined. Two indirect methods for estimating boundary-layer heights from the length scales of convective motions in the layer are also discussed.

William H. Hooke

Papers

Waves in the atmosphere

Ionospheric irregularities produced by internal atmospheric gravity waves

Waves in the atmosphere : atmospheric infrasound and gravity waves : their generation and propagation

The ionospheric response to internal gravity waves: 1. The F2 region response

Estimating the Depth of the Daytime Convective Boundary Layer