A Study of Orographic Effects in Models of the Large Scale Atmospheric Flow PDF Download

Author: Åke Johansson
Publisher:
ISBN: 9789171466587
Category :
Languages : en
Pages : 27

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Author: Åke Johansson
Publisher:
ISBN:
Category : Atmospheric circulation
Languages : en
Pages : 48

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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 836

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Author: Yangang Liu
Publisher: John Wiley & Sons
ISBN: 1119528992
Category : Science
Languages : en
Pages : 483

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Improving weather and climate prediction with better representation of fast processes in atmospheric models Many atmospheric processes that influence Earth’s weather and climate occur at spatiotemporal scales that are too small to be resolved in large scale models. They must be parameterized, which means approximately representing them by variables that can be resolved by model grids. Fast Processes in Large Scale Atmospheric Models: Progress, Challenges and Opportunities explores ways to better investigate and represent multiple parameterized processes in models and thus improve their ability to make accurate climate and weather predictions. Volume highlights include: Historical development of the parameterization of fast processes in numerical models Different types of major sub-grid processes and their parameterizations Efforts to unify the treatment of individual processes and their interactions Top-down versus bottom-up approaches across multiple scales Measurement techniques, observational studies, and frameworks for model evaluation Emerging challenges, new opportunities, and future research directions 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.

Author: F. Martin Ralph
Publisher: Springer Nature
ISBN: 3030289060
Category : Science
Languages : en
Pages : 284

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This book is the standard reference based on roughly 20 years of research on atmospheric rivers, emphasizing progress made on key research and applications questions and remaining knowledge gaps. The book presents the history of atmospheric-rivers research, the current state of scientific knowledge, tools, and policy-relevant (science-informed) problems that lend themselves to real-world application of the research—and how the topic fits into larger national and global contexts. This book is written by a global team of authors who have conducted and published the majority of critical research on atmospheric rivers over the past years. The book is intended to benefit practitioners in the fields of meteorology, hydrology and related disciplines, including students as well as senior researchers.

Author: Y. K. Chan
Publisher:
ISBN: 9789814535762
Category : SCIENCE
Languages : en
Pages : 621

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Author: John David Lindeman
Publisher:
ISBN:
Category : Mountain wave
Languages : en
Pages : 138

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Orographically generated gravity waves, or mountain waves, have been the focus of much research for decades because of their importance on the general mean atmospheric circulation. These waves affect the flow on scales which are too small to be resolved by global weather and climate models, and so their impact on the larger scale flow must be parameterized. Linear theory has proven useful for obtaining a quantitative understanding of wave processes and their effects on the background flow, though one must assume that the low level flow in mountainous regions is approximately linear. Numerical simulations and field experiments indicate that this is often not the case, however, as nonlinear effects can dominate the flow near the orography. These nonlinear effects, which include processes such as flow splitting around a mountain or upstream blocking of the flow, affect gravity wave generation and decrease the accuracy of predictions based on linear theory. The purpose of this dissertation is to investigate the extent that linear theory-based mountain wave predictions can be improved by using an alternative initialization scheme. Linear orographic gravity wave models traditionally have been initialized at the lower boundary assuming the orography is equivalent to the surface vertical displacement field. While this method works when wave-induced perturbations are small compared to the mean flow, this has been shown to fail in weak flow regimes and tall mountains. We introduce an initialization technique where the linear model is initialized on a horizontal plane with results from a corresponding simulation from a nonlinear numerical model. The height level of initialization must be in a region in which the flow can be approximated by linear theory, and in practice this occurs above the low level nonlinear processes in the vicinity of the mountain. We show that this method leads to greater accuracy in the solutions of the wavefield above the orography. This new method is tested for flow regimes of uniform background wind and stability, and for simple bell shaped hills and more complex and realistic orography. Parameters derived from linear theory which are useful for global weather models are shown to be significantly affected by the new initialization scheme. These results have the potential to quantitatively improve global weather model mountain wave parameterization schemes in the relatively common instance of orographically-induced nonlinear flows, as well as to provide quick and accurate forecasts of wave activity for the aviation community.

Author: L. M. Polvani
Publisher: John Wiley & Sons
ISBN: 1118671597
Category : Science
Languages : en
Pages : 514

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Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 190. The Stratosphere: Dynamics, Transport, and Chemistry is the first volume in 20 years that offers a comprehensive review of the Earth's stratosphere, increasingly recognized as an important component of the climate system. The volume addresses key advances in our understanding of the stratospheric circulation and transport and summarizes the last two decades of research to provide a concise yet comprehensive overview of the state of the field. This monograph reviews many important aspects of the dynamics, transport, and chemistry of the stratosphere by some of the world's leading experts, including up-to-date discussions of Dynamics of stratospheric polar vortices Chemistry and dynamics of the ozone hole Role of solar variability in the stratosphere Effect of gravity waves in the stratosphere Importance of atmospheric annular modes This volume will be of interest to graduate students and scientists who wish to learn more about the stratosphere. It will also be useful to atmospheric science departments as a textbook for classes on the stratosphere.

Author: Miguel A. C. Teixeira
Publisher: Frontiers Media SA
ISBN: 2889450163
Category :
Languages : en
Pages : 162

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Mountainous regions occupy a significant fraction of the Earth's continents and are characterized by specific meteorological phenomena operating on a wide range of scales. Being a home to large human populations, the impact of mountains on weather and hydrology has significant practical consequences. Mountains modulate the climate and create micro-climates, induce different types of thermally and dynamically driven circulations, generate atmospheric waves of various scales (known as mountain waves), and affect the boundary layer characteristics and the dispersion of pollutants. At the local scale, strong downslope winds linked with mountain waves (such as the Foehn and Bora) can cause severe damage. Mountain wave breaking in the high atmosphere is a source of Clear Air Turbulence, and lee wave rotors are a major near-surface aviation hazard. Mountains also act to block strongly stratified air layers, leading to the formation of valley cold air-pools (with implications for road safety, pollution, crop damage, etc.) and gap flows. Presently, neither the fine-scale structure of orographic precipitation nor the initiation of deep convection by mountainous terrain can be resolved adequately by regional-to global-scale models, requiring appropriate downscaling or parameterization. Additionally, the shortest mountain waves need to be parameterized in global weather and climate prediction models, because they exert a drag on the atmosphere. This drag not only decelerates the global atmospheric circulation, but also affects temperatures in the polar stratosphere, which control ozone depletion. It is likely that both mountain wave drag and orographic precipitation lead to non-trivial feedbacks in climate change scenarios. Measurement campaigns such as MAP, T-REX, Materhorn, COLPEX and i-Box provided a wealth of mountain meteorology field data, which is only starting to be explored. Recent advances in computing power allow numerical simulations of unprecedented resolution, e.g. LES modelling of rotors, mountain wave turbulence, and boundary layers in mountainous regions. This will lead to important advances in understanding these phenomena, as well as mixing and pollutant dispersion over complex terrain, or the onset and breakdown of cold air pools. On the other hand, recent analyses of global circulation biases point towards missing drag, especially in the southern hemisphere, which may be due to processes currently neglected in parameterizations. A better understanding of flow over orography is also crucial for a better management of wind power and a more effective use of data assimilation over complex terrain. This Research Topic includes contributions that aim to shed light on a number of these issues, using theory, numerical modelling, field measurements, and laboratory experiments.

Author: Michael John Priestley Cullen
Publisher: World Scientific
ISBN: 1783260408
Category : Science
Languages : en
Pages : 274

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This book counteracts the current fashion for theories of “chaos” and unpredictability by describing a theory that underpins the surprising accuracy of current deterministic weather forecasts, and it suggests that further improvements are possible. The book does this by making a unique link between an exciting new branch of mathematics called “optimal transportation” and existing classical theories of the large-scale atmosphere and ocean circulation. It is then possible to solve a set of simple equations proposed many years ago by Hoskins which are asymptotically valid on large scales, and use them to derive quantitative predictions about many large-scale atmospheric and oceanic phenomena. A particular feature is that the simple equations used have highly predictable solutions, thus suggesting that the limits of deterministic predictability of the weather may not yet have been reached. It is also possible to make rigorous statements about the large-scale behaviour of the atmosphere and ocean by proving results using these simple equations and applying them to the real system allowing for the errors in the approximation. There are a number of other titles in this field, but they do not treat this large-scale regime.