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.
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.
A technique for visualizing Earth's subsurface at high resolution Hidden out of sight in Earth’s subsurface are a range of geophysical structures, processes, and material movements. Muography is a passive and non-destructive remote sensing technique that visualizes the internal structure of solid geological structures at high resolution, similar in process to X-ray radiography of human bodies. Muography: Exploring Earth's Subsurface with Elementary Particles explores the application of this imaging technique in the geosciences and how it can complement conventional geophysical observations. Volume highlights include: Principles of muography and pioneering works in the field Different approaches for muographic image processing Observing volcanic structures and activity with muography Using muography for geophysical exploration and mining engineering Potential environmental applications of muography Latest technological developments in muography The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
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.
A multitude of processes that operate in the upper atmosphere are revealed by detailed physical and mathematical descriptions of the interactions of particles and radiation, temperatures, spectroscopy and dynamics.
Interest in the meteorology of the stratosphere and mesophere has been simulated in the past few years by concerns over possible depletion of the ozone layer as a result of reactions involving pollutants introduced by human activities. Concurrently there has been an upsurge in research on various aspects of the meteorology of the stratosphere. This monograph provides an account of the fundamental dynamical processes which control the general circulation of the stratosphere and mesophere and are thus responsible for the transport of trace substances in that region of the atmosphere. Principles necessary for understanding the dynamics of large-scale motions in the stratosphere and mesosphere are systematically developed so that this monograph should prove useful not only as a reference work for research scientists, but as a textbook for courses in dynamic meteorology of the upper atmosphere.
Ch. 1. Introduction and overview. 1.1. General introduction. 1.2. Basic properties of the Earth's atmosphere. 1.3. What is LTE? 1.4. Non-LTE situations. 1.5. The importance of non-LTE. 1.6. Some historical background. 1.7. Non-LTE models. 1.8. Experimental studies of non-LTE. 1.9. Non-LTE in planetary atmospheres. 1.10. References and further reading -- ch. 2. Molecular spectra. 2.1. Introduction. 2.2. Energy levels in diatomic molecules. 2.3. Energy levels in polyatomic molecules. 2.4. Transitions and spectral bands. 2.5. Properties of individual vibration-rotation lines. 2.6. Interactions between energy levels. 2.7. References and further reading -- ch. 3. Basic atmospheric radiative transfer. 3.1. Introduction. 3.2. Properties of radiation. 3.3. The radiative transfer equation. 3.4. The formal solution of the radiative transfer equation. 3.5. Thermodynamic equilibrium and local thermodynamic equilibrium. 3.6. The source function in non-LTE. 3.7. Non-LTE situations. 3.8. References and further reading -- ch. 4. Solutions to the radiative transfer equation in LTE. 4.1. Introduction. 4.2. Integration of the radiative transfer equation over height. 4.3. Integration of the radiative transfer equation over frequency. 4.4. Integration of the radiative transfer equation over solid angle. 4.5. References and further reading -- ch. 5. Solutions to the radiative transfer equation in non-LTE. 5.1. Introduction. 5.2. Simple solutions for radiative transfer under non-LTE. 5.3. The full solution of the radiative transfer equation in non-LTE. 5.4. Integration of the RTE in non-LTE. 5.5. Intercomparison of non-LTE codes. 5.6. Parameterizations of the non-LTE cooling rate. 5.7. The Curtis matrix method. 5.8. References and further reading -- ch. 6. Non-LTE modelling of the Earth's atmosphere I: CO2. 6.1. Introduction. 6.2. Useful approximations. 6.3. Carbon dioxide, CO2. 6.4. References and further reading -- ch. 7. Non-LTE modelling of the Earth's atmosphere II: Other infrared emitters. 7.1. Introduction. 7.2. Carbon monoxide, CO. 7.3. Ozone, O3. 7.4. Water vapour, H2O. 7.5. Methane, CH4. 7.6. Nitric oxide, NO. 7.7. Nitrogen dioxide, NO2. 7.8. Nitrous oxide, N2O. 7.9. Nitric acid, HNO3. 7.10. Hydroxyl radical, OH. 7.11. Molecular oxygen atmospheric infrared bands. 7.12. Hydrogen chloride, HC1, and hydrogen fluoride, HF. 7.13. NO+. 7.14. Atomic Oxygen, O (3P), at 63[symbol]m. 7.15. References and further reading -- ch. 8. Remote sensing of the non-LTE atmosphere. 8.1. Introduction. 8.2. The analysis of emission measurements. 8.3. Observations of carbon dioxide in emission. 8.4. Observations of ozone in emission. 8.5. Observations of water vapour in emission. 8.6. Observations of carbon monoxide in emission. 8.7. Observations of nitric oxide in emission. 8.8. Observations of other infrared emissions. 8.9. Rotational non-LTE. 8.10. Absorption measurements. 8.11. Simulated limb emission spectra at high resolution. 8.12. Simulated Nadir emission spectra at high resolution. 8.13. Non-LTE retrieval schemes. 8.14. References and further reading -- ch. 9. Cooling and heating rates. 9.1. Introduction. 9.2. CO2 15 f[symbol]m cooling. 9.3. O3 9.6[symbol]xm cooling. 9.4. H2O 6.3[symbol]m cooling. 9.5. NO 5.3[symbol]m cooling. 9.6. O(3Pi) 63[symbol]m cooling. 9.7. Summary of cooling rates. 9.8. CO2 solar heating. 9.9. References and further reading -- ch. 10. Non-LTE in planetary atmospheres. 10.1. Introduction. 10.2. The terrestrial planets: Mars and Venus. 10.3. A non-LTE model for the Martian and Venusian atmospheres. 10.4. Mars. 10.5. Venus. 10.6. Outer planets. 10.7. Titan. 10.8. Comets. 10.9. References and further reading.
Everyone is familiar with the daily changes of air temperature. The barometer shows that these are accompanied by daily changes of mass distribution of the atmosphere, and consequently with daily motions of the air. In the tropics the daily pressure change is evident on the barographs; in temperate and higher latitudes it is not noticeable, being overwhelmed by cyclonic and anticyclonic pressure variations. There too, however, the daily change can be found by averaging the variations over many days; and the same process suffices to show that there is a still smaller lunar tide in the atmosphere, first sought by Laplace. Throughout nearly two centuries these 'tides', thermal and gravitational, have been extensively discussed in the periodical literature of science, although they are very minor phenomena at ground level. This monograph summarizes our present knowledge and theoretical under standing of them. It is more than twenty years since the appearance of the one previous monograph on them - by Wilkes - and nearly a decade since they were last comprehensively reviewed, by Siebert. The intervening years have seen many additions to our know ledge of the state of the upper atmosphere, and of the tides there, on the basis of measurements by radio, rockets and satellites.
