Download or read book Modeling and Parameterization of Gravity Wave Breaking Interactions and Instability Processes in the Lower and Middle Atmosphere written by and published by . This book was released on 1994 with total page 5 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 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 Numerical Modeling and Parameterization of Gravity Wave Processes and Effects in the Atmosphere written by and published by . This book was released on 1991 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical modeling effort was started which is now providing high- resolution 2-d simulations of compressible nonlinear gravity wave dynamics using a state-of-the-art pseudo-spectral code. These results are a substantial improvement over previous efforts to address the fundamentals of gravity wave breaking, spectral evolution, and momentum and energy transports in the middle atmosphere.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 500 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 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Interaction Between Gravity Waves and Atmospheric Thermal Tides written by Ryan Matthew Agner and published by . This book was released on 2017 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract Gravity waves and thermal tides are two of the most important dynamical features of the atmosphere. They are both generated in the lower atmosphere and propagate upward transporting energy and momentum to the upper atmosphere. This dissertation focuses on the interaction of these waves in the Mesosphere and Lower Thermosphere (MLT) region of the atmosphere using both observational data and Global Circulation Model (GCMs). The first part of this work focuses on observations of gravity wave interactions with the tides using both LIDAR data at the Star Fire Optical Range (SOR, 35°N, 106.5°W) and a meteor radar data at the Andes LIDAR Observatory (ALO, 30.3°s, 70.7°W). At SOR, the gravity waves are shown to enhance or damp the amplitude of the diurnal variations dependent on altitude while the phase is always delayed. The results compare well with previous mechanistic model results and with the Japanese Atmospheric General circulation model for Upper Atmosphere Research (JAGUAR) high resolution global circulation model. The meteor radar observed the GWs to almost always enhance the tidal amplitudes and either delay or advance the phase depending on the altitude. When compared to previous radar results from the same meteor radar when it was located in Maui, Hawaii, the Chile results are very similar while the LIDAR results show significant differences. This is because of several instrument biases when calculating GW momentum fluxes that is not significant when determining the winds. The radar needs to perform large amounts of all-sky averaging across many weeks, while the LIDAR directly detects waves in a small section of sky. The second part of this work focuses on gravity wave parameterization scheme effects on the tides in GCMs. The Specified Dynamics Whole Atmosphere Community Climate Model (SD-WACCM) and the extended Canadian Middle Atmosphere Model (used for this analysis. The gravity wave parameterization schemes in the scheme) have been shown to enhance the tidal amplitudes compared to observation is the parameterization scheme in SD-WACCM (Lindzen scheme) overdamps eCMAM) are eCMAM (Hines while the tides. It is shown here that the Hines scheme assumption that only small scale gravity waves force the atmosphere do not create enough drag to properly constrain the tidal amplitudes. The Lindzen scheme produces too much drag because all wave scales are assumed to be saturated thus continuing to provide forcing on the atmosphere above the breaking altitude. The final part of this work investigates GWs, tides and their interactions on a local time scale instead of a global scale in the two GCMs. The local time GW's in eCMAM are found to have a strong seasonal dependence, with the majority of the forcings at the winter pole at latitudes where the diurnal variations are weak limiting their interactions. In SD-WACCM, the largest local GW forcings are located at mid latitudes near where the diurnal variations peak causing them to dampen the diurnal amplitudes. On a local time level the diurnal variations may be a summation of many tidal modes. The analysis reveals that in eCMAM the DW1 tidal mode is by far the dominant mode accounting for the local time variations. The high amount of modulation of GWs by the DW1 tidal winds does not allow it to be properly constrained, causing it to dominate the local time diurnal variations. Similarly, the DW1 projection of GW forcing is dominant over all other modes and contributes the most to the local time diurnal GW variations. The local time wind variations in SD-WACCM are influenced by several tidal modes because the DW1 tide is of compatible amplitudes to other modes. This is because of the increased damping on the tide by the GWs. It is also found that the local GW diurnal variations have significant contributions from all tidal modes due to the time and location of the forcing being dependent only on the tropospheric source regions and not the at altitude tidal winds.
Download or read book Aeronomy of the Earth s Atmosphere and Ionosphere written by Mangalathayil Ali Abdu and published by Springer Science & Business Media. This book was released on 2011-02-26 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a multi-author treatise on the most outstanding research problems in the field of the aeronomy of the Earth’s atmosphere and ionosphere, encompassing the science covered by Division II of the International Association of Geomagnetism and Aeronomy (IAGA). It contains several review articles and detailed papers by leading scientists in the field. The book is organized in five parts: 1) Mesosphere-Lower Thermosphere Dynamics and Chemistry; 2) Vertical Coupling by Upward Propagating Waves; 3) Ionospheric Electrodynamics and Structuring; 4) Thermosphere- Ionosphere Coupling, Dynamics and Trends and 5) Ionosphere-Thermosphere Disturbances and Modeling. The book consolidates the progress achieved in the field in recent years and it serves as a useful reference for graduate students as well as experienced researchers.
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 Encyclopedia of Global Warming and Climate Change Second Edition written by S. George Philander and published by SAGE Publications. This book was released on 2012-06-13 with total page 2022 pages. Available in PDF, EPUB and Kindle. Book excerpt: The First Edition of the Encyclopedia of Global Warming and Climate Change provided a multi-authored, academic yet non-technical resource for students and teachers to understand the importance of global warming, to appreciate the effects of human activity and greenhouse gases around the world, and to learn the history of climate change and the research enterprise examining it. This edition was well received, with notable reviews. Since its publication, the debate over the advent of global warming at least partially brought on by human enterprise has continued to ebb and flow, depending literally on the weather, politics, and media coverage of climate summits and debates. Advances in research also change the discourse as new data is collected and new scientific projects continue to explore and explain global warming and climate change. Thus, a new, Second Edition updates more than half of the original entries and adds new perspectives and content to keep students and researchers up-to-date in a field that has proven provocatively lively.
Download or read book Encyclopedia of Atmospheric Sciences written by Gerald R. North and published by Elsevier. This book was released on 2014-09-14 with total page 2874 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encyclopedia of Atmospheric Sciences, Second Edition, Six Volume Set is an authoritative resource covering all aspects of atmospheric sciences, including both theory and applications. With more than 320 articles and 1,600 figures and photographs, this revised version of the award-winning first edition offers comprehensive coverage of this important field. The six volumes in this set contain broad-ranging articles on topics such as atmospheric chemistry, biogeochemical cycles, boundary layers, clouds, general circulation, global change, mesoscale meteorology, ozone, radar, satellite remote sensing, and weather prediction. The Encyclopedia is an ideal resource for academia, government, and industry in the fields of atmospheric, ocean, and environmental sciences. It is written at a level that allows undergraduate students to understand the material, while providing active researchers with the latest information in the field. Covers all aspects of atmospheric sciences—including both theory and applications Presents more than 320 articles and more than 1,600 figures and photographs Broad-ranging articles include topics such as atmospheric chemistry, biogeochemical cycles, boundary layers, clouds, general circulation, global change, mesoscale meteorology, ozone, radar, satellite remote sensing, and weather prediction An ideal resource for academia, government, and industry in the fields of atmospheric, ocean, and environmental sciences
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
Download or read book Middle Atmosphere Program Condensed minutes of the MAP Steering Committee meetings held in Hamburg 13 14 August 1983 research recommendations for increased US participation in the Middle Atmosphere Program written by and published by . This book was released on 1981 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Modeling of Wave and Instability Processes in the Atmosphere written by and published by . This book was released on 1996 with total page 3 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goals of this research were to examine the dynamics of internal gravity waves accompanying wave breaking and shear flow instability processes using spectral collocation techniques. Important aspects of these flows are the development of instabilities within the flow field which drive the cascade of energy and enstrophy toward turbulence. We also anticipated that these processes would be sensitive to the environment in which they occurred. Our numerical results described showed this to be true.
Download or read book Small Scale Processes in the Mesosphere lower Thermosphere Region written by Markus Rapp and published by . This book was released on 2007 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Numerical Investigation of Turbulence driven and Forced Generation of Internal Gravity Waves in Stratified Mid water written by Ammar Mohammed Abdilghanie and published by . This book was released on 2011 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Natural and externally-forced excitation of internal gravity waves in a uniformly stratified fluid have been thoroughly investigated by means of highly resolved large eddy simulations. The first part of the thesis focuses on the generation of high frequency internal gravity waves by the turbulent wake of a towed sphere in a uniformly stratified fluid. We have used continuous wavelet transforms to quantify relevant wavelength and frequencies and their spatial and temporal dependence in the near field of the wake. The dependence on Reynolds number and Froude number of the internal wave field wavelengths, frequencies and isopycnal displacements are reported for the first time. The initial wavelengths and decay rates show a dependence on both parameters that can not be explained on the basis of impulsive mass source models. The results also clearly identify Reynolds number as the main driver for the observed selection of a narrow range of wave phase- line-tilt-angles and shed some light on the coupling of the waves and turbulent wake region at high Reynolds number. Finally, the potential for nonlinear interactions, instability and breaking of the waves increases with both Reynolds and Froude numbers. The results of this part of the thesis motivate future theoretical investigations into the underlying generation mechanisms and improved parametrization of the role of small scale processes, such as high frequency internal gravity waves, in large scale circulation models in the ocean and atmosphere. In the second half of the thesis, we have focused on the generation of an internal gravity wavepacket by a vertically localized transient forcing. We have found that the unique combination of strong vertical localization and large wave amplitude, typically not considered in the literature, lead to the formation of strong horizontal mean flow inside the wave forcing region that nonlinearly grows at the expense of a depleted and structurally modified emerging internal wave packet. A novel theoretical analysis is developed which can explain the underlying mechanism for the formation of the mean flow. By appealing to scaling arguments, based on a one way wave-mean flow interaction, we quantify the mean flow dependence on the input parameters. By means of a phase averaging procedure, we offer additional insight on mean flow reduction through horizontal localization of a wavepacket. Finally, mean flow containment techniques that allow the generation of a well-defined wavepacket that preserves its structure near the source and during the propagation towards a remote interaction region are proposed and tested. The efficiency of the techniques is tested in a simulation of internal gravity wave-shear flow interaction near a critical level. The simulations qualitatively agree with previous numerical investigations of such flow.
