Download or read book An Investigation of Gravity Wave Saturation Processes in the Lower Stratosphere and Mesosphere written by Hua-Guo Chou and published by . This book was released on 1987 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gravity Wave Processes written by Kevin Hamilton and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: The subject of this volume is the observation and modelling of the gravity wave field in the atmosphere. The focus is on the question of how to include the effects of small-scale gravity waves in sophisticated global climate models. The book comprises 26 chapters, including contributions from distinguished experts in observation and theory, along with results from studies of gravity wave parameterization within comprehensive climate models.
Download or read book Evidence of Gravity Wave Saturation and Local Turbulence Production in the Summer Mesosphere and Lower Thermosphere During the STATE Structure and Atmospheric Turbulence Environment Experiment written by and published by . This book was released on 1988 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study used the unique data set obtained during the Structure and Atmospheric Turbulence Environment (STATE) experiment, conducted during June 1983 at Poker Flat, Alaska, to examine the structure and characteristics of the wave field near the summer mesopause. It is shown that the rocket and radar data together permit a much more detailed specification of wave parameters than would be possible using either data set alone. Results of this analysis suggest that the wave field near the summer mesopause is composed, in general, of a superposition of wave motions which act collectively to produce regions in which the wave field is convectively or dynamically unstable. These regions are found to correlate well with zones of enhanced turbulence and small-scale wave activity, suggesting the processes and effects of wave field saturation. Keywords: Gravity waves; Instability; Mesosphere; Thermosphere. Reprints.
Download or read book A Study of Gravity Wave Variability Saturation and Turbulence Generation in the Mesosphere and Lower Thermosphere written by David C. Fritts and published by . This book was released on 1989 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our principal research objectives were to understand the characteristics of and the processes controlling the fluctuations of velocity, density, and optical properties due to wave and turbulence motions in the middle atmosphere. It was hoped that an increased understanding of these motions and their variability would lead to a better predictive capability for their influence on in situ and ground-based systems using this region in the future. Research progress was made on several fronts. Theoretical efforts focussed on wave propagation and saturation processes, the effects of varying stratification on wave saturation and wave transports of energy and momentum, and the influences of chemical recombination on ion and neutral fluctuations due to waves and turbulence. (edc).
Download or read book Coupling Processes in the Lower and Middle Atmosphere written by E.V. Thrane and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NATO Advanced Research Workshop on Coupling Processes in the Lower and Middle atmosphere held in Loen, Norway in May 1992 was, in the estimation of apparently all participants, an enormous success. The 18 invited speakers included many of the leaders in the field and resulted in the attendance of a large number of contributing speakers and observers. The subject of the workshop was itself very timely, given the increasing awareness within the international community of the sensitivity of the atmosphere to coupling between adjacent layers, different latitudes, and various scales of motion. It was also very beneficial to bring together researchers with different approaches to the same or similar problems. For example, experimentalists benefitted from the inputs of modelers and theoreticians concerning the needs of current models and the most pressing problems and unknowns. Likewise, theoreticians were challenged to apply themselves to realistic problems and saw their theories tested against geophysical data. These discussions led to meaningful exchanges of ideas and challenges to or displacement of conventional wisdom in some areas. Indeed, possibly the greatest benefit of the workshop was the exposure of many participants to other areas of research or approaches to problems relevant to their own work. Workshop topics were confined to dynamical coupling processes in order to examine progress in a relatively focussed area. Nevertheless, the results presented spanned spatial scales from molecular to global and temporal scales from seconds to decades.
Download or read book Middle Atmosphere written by PLUMB and published by Birkhäuser. This book was released on 2013-11-21 with total page 465 pages. Available in PDF, EPUB and Kindle. Book excerpt: PAGEOPH, stratosphere, these differences provide us with new evidence, interpretation of which can materially help to advance our understanding of stratospheric dynamics in general. It is now weil established that smaller-scale motions-in particular gravity waves and turbulence-are of fundamental importance in the general circulation of the mesosphere; they seem to be similarly, if less spectacularly, significant in the troposphere, and probably also in the stratosphere. Our understanding of these motions, their effects on the mean circulation and their mutual interactions is progressing rapidly, as is weil illustrated by the papers in this issue; there are reports of observational studies, especially with new instruments such as the Japanese MV radar, reviews of the state of theory, a laboratory study and an analysis of gravity waves and their effects in the high resolution "SKYHI" general circulation model. There are good reasons to suspect that gravity waves may be of crucial significance in making the stratospheric circulation the way it is (modeling experience being one suggestive piece of evidence for this). Direct observational proof has thus far been prevented by the difficulty of making observations of such scales of motion in this region; in one study reported here, falling sphere observations are used to obtain information on the structure and intensity of waves in the upper stratosphere.
Download or read book An Observational Investigation on Gravity Wave Characteristics and Propagation in the Lower Stratosphere and Mesopause written by Zhenhua Li and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, investigations on gravity waves are conducted in two regions of the middle atmosphere: the lower stratosphere using high-resolution radiosonde at South Pole and the mesopause region using OH airglow imager at Maui, Hawaii and Cerro Pachon, Chile. Wave characteristics at these regions are deduced and the seasonal variation of wave activity, wave sources, and propagation effect are studied. The study of gravity waves in the lower stratosphere at South Pole reveals that sources other than topography are important even for the lower part of middle atmosphere. Horizontal propagation must be included in parameterization schemes to reflect the fact that waves derived from radiosondes have slant propagation paths. They travel long distance horizontally before they reach higher altitudes. Long term gravity wave characteristics over Maui from 2002 to 2007 are deduced from OH airglow imager. Wave parameters from the long term imager observation provide robust statistics of high-frequency gravity wave in the midlatitudes. Poleward wave propagation preference during summer and equatorward wave propagation preference during winter are observed over Maui. They are also opposite to the seasonal mean meridional wind direction which are always pointing toward winter pole. Momentum fluxes deduced from OH imager are also highly anti-correlated with background winds. At least for the part of spectrum observed by airglow imager, gravity waves act as damping mechanism for diurnal tide. Gravity wave occurrence frequency does not follow the variation of local convective sources and convective sources in a large domain when ducted waves are considered. In fact, with a constant wave source and monthly mean background atmospheric condition, the simulated wave transmission resembles the wave occurrence frequency observed by OH airglow imager at Maui. Thus, at Maui the propagation effect dominates the seasonal variation in wave activity. Gravity wave momentum fluxes deduced from airglow imager provide important observation constraint for gravity wave parameterization for the mesopause region. To explain the cause of seasonal change on meridional propagation preference, three mechanisms are investigated: critical-layer filtering, wave ducting, and Doppler-shifting by local mean wind. Critical-layer filtering failed to explain the propagation preference. Observed gravity wave propagation directions are largely related to the background wind in the airglow layer. This is caused by Doppler-shifting of gravity waves by background wind. Background wind Doppler shifts gravity waves propagating against (along) background wind to higher (lower) frequency and larger (smaller) vertical wavelength. Thus, the observed gravity waves tend to propagate against background wind. The apparent against background wind propagation is largely caused by the contrast in cancellation factor for waves propagate in different direction. To a lesser degree, the difference in dissipation for waves propagate in different direction also contributes to the observed against background wind propagation. The results from this work show gravity wave's propagation in middle atmosphere is strongly affected by atmospheric field. For low frequency waves, their propagation paths are slant and can travel hundreds of kilometers before they reach the middle atmosphere. For high frequency gravity waves, though their propagation paths are mostly vertical, they are subject to ducting and reflection. Due to the large contribution of momentum flux in the Mesosphere and Lower Thermosphere (MLT) by high-frequency, short-horizontal-scale waves, these propagation effects must be included in gravity wave parameterizations.
Download or read book Dynamical Processes of Gravity Waves Propagation and Dissipation and Statistical Characteristics of Their Momentum Flux in the Mesosphere and Lower Thermosphere written by Bing Cao and published by . This book was released on 2017 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract The mesosphere and lower thermosphere (MLT) (~80-110 km) is dominated by abundant atmospheric waves, of which gravity waves are one of the least understood due to large varieties in wave characteristics as well as potential sources. Gravity waves play an important role in the atmosphere by influencing the thermal balance and helping to drive the global circulation. But due to their sub-grid scale, the effects of gravity waves in General Circulation Models (GCMs) are mostly parameterized. The investigations of gravity waves in this dissertation are from two perspectives: the dynamical processes of gravity wave propagation and dissipation in the MLT region, and the climatology and statistical characteristics of gravity waves as physical basics of gravity wave parameterization. The studies are based on the data acquired from an airglow imager and a sodium lidar, with the assistance of some simulation data from a meso-scale numerical model and GCMs. To understand the dynamical processes in gravity wave propagation and dissipation, a gravity wave should be resolved as fully as possible. The first topic of this dissertation is motivated by the fact that most observational instruments can only capture part of the gravity waves spectrum, either horizontal or vertical structures. Observations from multiple complementary instruments are used to study gravity waves in 3-D space. There are two cases included in this topic. In case 1, a co-located sodium lidar and an airglow imager were used to depict a comprehensive picture of a wave event at altitude between 95-105 km. Thus, the horizontal and vertical gravity waves structures and their ambient atmosphere states were fully characterized, which suggests that a gravity wave undergoes reflection at two different altitudes and near-critical layer filtering in-between. All the retrieved parameters were then applied to a 2-D numerical model whose outputs help to interpret the observations. In case 2, the lidar system is configured in a 5-direction mode, whose laser beams were pointed to zenith and 30° off-zenith at four cardinal directions. Thus, there is a ~50 km separation at 90 km altitude between zenith and any off-zenith directions. Besides the vertical information from traditional lidar measurement pro horizontal wavelength and propagation direction are derived from the phase among measurements in different directions. With a full set of wave and parameters, multiple dispersion validate the goodness of different assumptions involved in linear gravity wave files, differences background and polarization relations are examined and the results theory Better knowledge of gravity waves from observational and numerical, as well as theoretical studies directly contribute to the development of physically-based parameterizations. The second topic of this dissertation is about long-term climatology and statistical characteristics of gravity waves observed by an airglow imager. The results provide some insights on how the source spectrum can be specified and tuning factors are constrained in the parameterization. Results from two sites are compared, one is in the middle of the Pacific Ocean, and the other above the Andes Mountains. The difference and similarity provide some clues to the effects of wave sources and background flow on the gravity wave climatology and intermittency in the mesopause region. Firstly, the long-term climatology of intrinsic wave parameters and propagation direction preferences for high-frequency quasi-monochromatic gravity waves observed by an airglow imager is presented. Wave occurrence and propagation direction are related to convective activities nearby and local background winds. The preferential wave propagation during austral summer is poleward and equatorward during winter. The estimated momentum fluxes show a clear anti-correlation with background winds. Secondly, intermittency of gravity waves near mesopause region is studied. The concept of intermittency is originally from the factors used in wave parameterization schemes to describe the fractional coverage of waves within a large spatial grid and/or temporal period in order to accurately quantify the forcing on the atmosphere by dissipating gravity waves. Intermittency of gravity waves was described by the probability density functions of absolute momentum flux and some diagnostic parameters. An explicit probability function that is a piecewise function of lognormal and power law functions is obtained from airglow data. The relative importance of abundant waves with smaller amplitudes and rare waves with dramatically large amplitudes were compared. Lastly, the duration of gravity waves in the airglow layer is studied. The observed gravity waves duration in the airglow layer is exponentially distributed. Several mechanisms that could lead to such a distribution are put forward from the perspective of wave breaking due to instabilities and blocking due to evanescent regions. Ducted propagation is also a possible factor. Through individual cases and statistical studies, this dissertation investigates the dynamical processes and statistical characteristics of gravity in the MLT region. The results are expected to provide more insight in both observational and modeling research on gravity waves.
Download or read book Internal Gravity Waves written by Bruce R. Sutherland and published by Cambridge University Press. This book was released on 2010-09-02 with total page 395 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of internal gravity waves provides many challenges: they move along interfaces as well as in fully three-dimensional space, at relatively fast temporal and small spatial scales, making them difficult to observe and resolve in weather and climate models. Solving the equations describing their evolution poses various mathematical challenges associated with singular boundary value problems and large amplitude dynamics. This book provides the first comprehensive treatment of the theory for small and large amplitude internal gravity waves. Over 120 schematics, numerical simulations and laboratory images illustrate the theory and mathematical techniques, and 130 exercises enable the reader to apply their understanding of the theory. This is an invaluable single resource for academic researchers and graduate students studying the motion of waves within the atmosphere and ocean, and also mathematicians, physicists and engineers interested in the properties of propagating, growing and breaking waves.
Download or read book Middle Atmosphere Program Papers presented at the URSI written by and published by . This book was released on 1981 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Middle Atmosphere Program written by and published by . This book was released on 1981 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modifications of General Circulation Due to Saturation and Transience of Orographic Gravity Waves a Memoir written by Hiroshi Tanaka and published by . This book was released on 1999 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Upper Mesosphere and Lower Thermosphere written by R. M. Johnson and published by American Geophysical Union. This book was released on 1995-01-09 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 87. This volume provides a review of progress made in recent years in experimental and theoretical investigation of the upper mesosphere and lower thermosphere and coupling between these regions and the ionosphere. Detailed study of the mesosphere/lower thermosphere/ionosphere (MLTI) region has historically been difficult because of its relative inaccessibility to direct measurement techniques and the complex and highly coupled processes which occur there. Although we have still not successfully unraveled all these complex interactions, we have made significant recent progress toward a fuller understanding of the basic state of the MLTI and of the dominant wave and coupling processes. This monograph includes a set of tutorial papers, which review our current understanding of aspects of the MLTI. These tutorials are interspersed with a selection of papers describing research progress on various topics of current interest in this region. The book should therefore be useful both to the newcomer, as an introduction to this field of research, and to the more experienced researcher, providing an overview of research in progress as well as a convenient reference collection of papers describing our current understanding.
Download or read book An Investigation of the Causes of Optical and Infrared Airglow Structures in the Mesosphere written by Edmond M. Dewan and published by . This book was released on 1994 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Internal Gravity Waves Observed in Mesospheric Temperature Measurements written by S. P. Zimmerman and published by . This book was released on 1970 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Temperature height profiles determined from falling sphere and Arcasonde measurements, made at White Sands, New Mexico from 23 to 25 January 1967, exhibit unusually large variability in the vicinity of the mesopause. Spatial and temporal analysis of the data exhibit a wave-like structure with vertical half wavelengths of the order of 3 and 30 km and a characteristic period of approximately 12 hours for the longer wavelength. Comparison with meteorological data below 60 km and application of appropriate theory leads to the tentative suggestion that the observed temperature variations were due to internal gravity waves. The analysis also infers that the source of these waves was a large scale, low altitude (approximately 200 mb) synoptic disturbance. This work has been performed in support of re-entry studies for Air Force space vehicles and investigations for improving DOD missile impact prediction capability. (Author).
Download or read book The Upper Atmosphere written by Walter Dieminger and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 1023 pages. Available in PDF, EPUB and Kindle. Book excerpt: Especially due to the increasing environmental problems there is a need to collect as many data as possible in the upper atmosphere. This book serves as a general multidisciplinary guide and introduction for a more effective use of the large amount of now available data from the Earth's atmosphere. It also shows the problems of the use of large amounts of time series data - for basic science as well as for environmental monitoring - and the related information systems. The book is aimed for scientists and students interested in the Earth's atmosphere which is vital for the understanding of environmental changes in the global system Earth.
Download or read book An Introduction to Atmospheric Gravity Waves written by Carmen J. Nappo and published by Elsevier. This book was released on 2002-09-12 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gravity waves exist in all types of geophysical fluids, such as lakes, oceans, and atmospheres. They play an important role in redistributing energy at disturbances, such as mountains or seamounts and they are routinely studied in meteorology and oceanography, particularly simulation models, atmospheric weather models, turbulence, air pollution, and climate research. An Introduction to Atmospheric Gravity Waves provides readers with a working background of the fundamental physics and mathematics of gravity waves, and introduces a wide variety of applications and numerous recent advances. Nappo provides a concise volume on gravity waves with a lucid discussion of current observational techniques and instrumentation. Foreword is written by Prof. George Chimonas, a renowned expert on the interactions of gravity waves with turbulence. CD containing real data, computer codes for data analysis and linear gravity wave models included with the text
