William H. Hooke
Other affiliations: Silver Spring Networks, Environmental Science Services Administration, National Oceanic and Atmospheric Administration ...read more
Bio: William H. Hooke is an academic researcher from American Meteorological Society. The author has contributed to research in topic(s): Ionosphere & Wave propagation. The author has an hindex of 15, co-authored 38 publication(s) receiving 1779 citation(s). Previous affiliations of William H. Hooke include Silver Spring Networks & Environmental Science Services Administration.
01 Jan 1975
TL;DR: In this paper, the authors propose a method to solve the problem of how to find the shortest path between two points of interest in a set of images. Index Reference Record created on 2004-09-07, modified on 2016-08-08
Abstract: Note: Bibliogr. : p. 423-440. Index Reference Record created on 2004-09-07, modified on 2016-08-08
TL;DR: In this article, a perturbation treatment is used to determine the nature and magnitude of the effects of internal atmospheric gravity waves on the ambient rates of production, chemical loss, and motion of the ionization.
Abstract: A perturbation treatment is used to determine the nature and magnitude of the effects of internal atmospheric gravity waves on the ambient rates of production, chemical loss, and motion of the ionization. The relative and absolute importance of these effects in the creation of ionospheric irregularities are assessed. This assessment yields several conclusions of particular interest. Firstly, in the F 2-region the dominant effect of the gravity waves is that of imparting the motion of the neutral gas parallel to the magnetic field to the ionization through collisional interaction. Secondly, at heights at or below the height of the F1 -ledge, chemical effects, in particular the effect of gravity waves on the rate of photoionization, are quite important. Thirdly, gravity waves affect the rate of photoionization at a given point by changing both the neutral gas number density and the ionizing radiation flux at that point, and this latter effect, hitherto ignored, is in some respects the more important of the two. Fourthly, as a result of the interplay of a number of factors, certain Fourier components of that portion of the gravity-wave spectrum permitted at ionospheric heights are more successful than others in creating observable disturbances. Finally, gravity waves creating neutral gas velocities of the order of 20 m sec −1 seem capable under the right conditions of creating TID's of the largest magnitudes observed.
01 Jan 1975
TL;DR: In this paper, the authors provide an introduction to the theory of propagation and the dynamics of mesoscale atmospheric masses and wave propagation in the field of radiophysics, as well as their role in the generation of clear air turbulence (CAT).
Abstract: 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.
TL;DR: In this paper, the F2 region ionospheric response to individual internal gravity waves is calculated as a function of the azimuth of wave propagation, and the 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.
Abstract: 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.
TL;DR: In this paper, three in-situ and five remote sensing techniques for measuring the height of the daytime convective boundary layer were compared, and 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.
Abstract: 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.
TL;DR: In this article, the effects of mean winds and gravity waves on the mean momentum budget were investigated and it was shown that the existence of critical levels in the mesosphere significantly limits the ability of gravity waves to generate turbulence.
Abstract: 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.
TL;DR: A comprehensive review of zonal flow phenomena in plasmas is presented in this article, where the focus is on zonal flows generated by drift waves and the back-interaction of ZF on the drift waves, and various feedback loops by which the system regulates and organizes itself.
Abstract: 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.
01 Jan 2000-Atmospheric Environment
TL;DR: In this paper, the authors present a review of the literature on the analysis of profile measurements and the use of parameterisations and simple models, and suggest for the preprocessor development and for future research activities.
Abstract: The height of the atmospheric boundary layer (ABL) or the mixing height (MH) is a fundamental parameter characterising the structure of the lower troposphere. Two basic possibilities for the practical determination of the MH are its derivation from profile data (measurements or numerical model output) and its parameterisation using simple equations or models (which only need a few measured input values). Different methods suggested in the literature are reviewed in this paper. The most important methods have been tested on data sets from three different sites in Europe (Cabauw – NL, Payerne – CH, Melpitz – D). Parcel and Richardson number methods applied to radiosonde profiles and the analysis of sodar and wind profiler data have been investigated. Modules for MH determination implemented in five currently used meteorological preprocessors for dispersion models have been tested, too. Parcel methods using a revised coefficient for the excess temperature and Richardson number methods using a surface excess temperature worked well under convective conditions. Under stable conditions, the inherent difficulties call for a combination of several methods (e.g., mast and sodar). All the tested parameterisation schemes showed deficiencies under certain conditions, thus requiring more flexible algorithms able to take into account changing and non-classical conditions. Recommendations are formulated regarding both the analysis of profile measurements and the use of parameterisations and simple models, and suggestions for the preprocessor development and for future research activities are presented.
01 May 1982-Reviews of Geophysics
TL;DR: A review of theoretical and observational results describing atmospheric gravity wave (AGW)/traveling ionospheric disturbance (TID) phenomena at high latitudes is presented in this paper.
Abstract: 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.
01 Aug 1993-Boundary-Layer Meteorology
TL;DR: Roll vortices may be loosely defined as quasi-two-dimensional organized large eddies with their horizontal axis extending through the whole planetary boundary layer (PBL), and their indirect manifestation is most obvious in so-called cloud streets as can be seen in numerous satellite pictures as mentioned in this paper.
Abstract: Roll vortices may be loosely defined as quasi two-dimensional organized large eddies with their horizontal axis extending through the whole planetary boundary layer (PBL). Their indirect manifestation is most obvious in so-called cloud streets as can be seen in numerous satellite pictures. Although this phenomenon has been known for more than twenty years and has been treated in a review by one of us (R.A.Brown) in 1980, there has been a recent resurgence in interest and information. The interest in ocena/land-atmosphere interactions in the context of climate modeling has led to detailed observational and modeling efforts on this problem. The presence of rolls can have a large impact on flux modelling in the PBL. Hence, we shall review recent advances in our understanding of organized large eddies in the PBL and on their role in vertical transport of momentum, heat, moisture and chemical trace substances within the lowest part of the atmosphere.