Download or read book Atmospheric Boundary Layer Modeling in Complex Terrain written by Yu Song and published by . This book was released on 1998 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling the atmospheric boundary layer in stably stratified conditions and over complex terrain areas written by Mireia Udina Sistach and published by . This book was released on 2015 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: The atmospheric boundary layer in stably-stratified conditions and over non-homogeneous terrain becomes a complex system with many interactions of physical processes occurring in a wide range of different spatial and temporal scales. During clear sky night-time or in any stably-stratified conditions intermittent turbulent events and gravity waves are usually present in the stable boundary layer (SBL), which can substantially modify the flow structure. In addition, the circulations in stable flows can be strongly driven by the underlying and surrounding topography, generating katabatic winds, density currents and low level jets, which in turn, trigger gravity waves and turbulence. This thesis aims to contribute to a better comprehension of some of the processes and phenomena occurring in the SBL and over complex terrain areas. In order to understand and quantify the unknown atmospheric processes one can distinguish three different procedures that are very well connected: theoretical descriptions, experimental campaigns and numerical modeling. The numerical models allow us to further understand the experimental data, to test the theoretical relationships or to simulate processes which are very difficult to measure. Principally, in this thesis we have used numerical models to deal with the uncertainties that arise in stably-stratified flows and over heterogeneous terrain and to explore the model capabilities and limitations to resolve them. These numerical weather prediction models (NWP) contain the primitive equations of the atmosphere to describe and forecast the flow motions and properties. In this thesis we have employed one of the worldwide known NWP model, the Weather Research and Forecasting (WRF) model, using two different approaches: the mesoscale approximation and the large eddy simulation (LES). While the mesoscale methodology has allowed us to investigate the flow circulation patterns in a wide range of scales, the LES approximation has enabled us to explicitly resolve the turbulence and describe its structure. In this thesis each methodology has been applied to investigate these different purposes. Using the WRF model with the mesoscale approach we have determined the origin of a density current that generated internal gravity waves over the "Centro de Investigaciones de la Baja Atmosfera"(CIBA) site. We have seen that the long distance mesoscale sea-breeze circulation and the night-time katabatic flows originated at the surrounding complex topography were the origin of the density current which generated displacement in the air parcels and periodic oscillations. In this thesis we have also investigated the vertical turbulence structure using the LES approximation of the WRF model. As a previous step, we have first validated the WRF-LES model in the SBL with a reference case by a comparison of the first and second order moments profiles. Using different wind speed initial conditions we reproduce neutrally and stably stratified flows. However, different from the reality, stably stratified flows are strongly coupled with the surface and turbulence is always maintained. We have shown how the turbulence intensity increases sharply with the wind speed at each height above ground but the rate of increase (slope) is not maintained, as we would expect. It seems that the the top domain potential temperature inversion affects the flow turbulence structure over the whole domain. Finally, we have studied topographically generated gravity waves over the Pyrenees and specifically simulated a trapped lee wave event using the mesoscale approximation with WRF. We have seen that the model is able to reproduce the gravity waves at the lee side of the mountain range with periodic oscillations in all magnitudes. We have seen that 1-km horizontal resolution is necessary to capture the wave field. We have also showed that upstream conditions have to be well represented to capture the adequate wave characteristics.

Download or read book Modelling Of Atmospheric Flow Fields written by Demetri P Lalas and published by World Scientific. This book was released on 1996-01-11 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is a collection of lectures given at the two colloquia on atmospheric flows over complex terrain with applications to wind energy and air pollution, organized and sponsored by ICTP in Trieste, Italy. The colloquia were the result of the recognition of the importance of renewable energy sources, an important aspect which grows yearly as the environmental problems become more pronounced and their effects more direct and intense, while at the same time, the wise management of the Earth's evidently limited resources becomes imperative.It is divided into two main parts. The first, which comprises Chaps. 1 to 4, presents the structure of the atmospheric boundary layer with emphasis in the region adjacent to the ground. The second, Chaps. 5 to 10, discusses methods for the numerical computation of the wind field on an arbitrary terrain. The unique feature of this book is that it does not stop at the theoretical exposition of the analytical and numerical techniques but includes a number of codes, in a diskette, where the mechanisms and techniques presented in the main part are implemented and can be run by the reader. Some of the codes are of instructional value while others can be utilized for simple operational work.Some of the lecturers are: D N Asimakopoulos, C I Aspliden, V R Barros, A K Blackadar, G A Dalu, A de Baas, D Etling, G Furlan, D P Lalas, P J Mason, C F Ratto and F B Smith.

Download or read book Numerical Modelling of Atmospheric Boundary layer Flows Over Complex Terrain written by Massimiliano Burlando and published by . This book was released on 2004 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Boundary Layer Structure written by Hadassah Kaplan and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this volume, we present the lectures given during the 1984 OHOLO Conference, held in Zichron Yaacov, Israel. The Conference was organized by the Israel Institute for Biological Research, Department of Mathematics, which is involved in Environmental Risk Evaluation, and in Projects Estimating the Potential of Wind Energy. The lectures cover a broad spectrum of mathematical models, ranging from those that deal with the solution of atmospheric conservation equations, and to those models that yield empirical estimates based on real time measure ments and thus are unique to the locale where measured. The goal of the Conference was to allow scientists from various countries to meet and discuss topics of mutual interest, including the following: 1. Structure of the boundary layer - primarily models dealing in the understanding of the various processes of atmospheric energy transfer, and their influence on the size and composition of the boundary 1 ayer. 2. Advanced mathematical techniques for describing flow and diffusion - lectures on approximations and techniques for solving the diffu sion and transport equations. 3. Flow over complex terrain - research into various aspects of the problem - mathematical models, physical models, experimental results. 4. Models of pollution transport and deposition.

Download or read book The Future of Atmospheric Boundary Layer Observing Understanding and Modeling written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2018-12-03 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Improved observations of the atmospheric boundary layer (BL) and its interactions with the ocean, land, and ice surfaces have great potential to advance science on a number of fronts, from improving forecasts of severe storms and air quality to constraining estimates of trace gas emissions and transport. Understanding the BL is a crucial component of model advancements, and increased societal demands for extended weather impact forecasts (from hours to months and beyond) highlight the need to advance Earth system modeling and prediction. New observing technologies and approaches (including in situ and ground-based, airborne, and satellite remote sensing) have the potential to radically increase the density of observations and allow new types of variables to be measured within the BL, which will have broad scientific and societal benefits. In October 2017, the National Academies of Sciences, Engineering, and Medicine convened a workshop to explore the future of BL observations and their role in improving modeling and forecasting capabilities. Workshop participants discussed the science and applications drivers for BL observation, emerging technology to improve observation capabilities, and strategies for the future. This publication summarizes presentations and discussions from the workshop.

Download or read book The Atmospheric Boundary Layer written by J. R. Garratt and published by Cambridge University Press. This book was released on 1994-04-21 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book gives a comprehensive and lucid account of the science of the atmospheric boundary layer (ABL). There is an emphasis on the application of the ABL to numerical modelling of the climate. The book comprises nine chapters, several appendices (data tables, information sources, physical constants) and an extensive reference list. Chapter 1 serves as an introduction, with chapters 2 and 3 dealing with the development of mean and turbulence equations, and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modelling of the ABL is crucially dependent for its realism on the surface boundary conditions, and chapters 4 and 5 deal with aerodynamic and energy considerations, with attention to both dry and wet land surfaces and sea. The structure of the clear-sky, thermally stratified ABL is treated in chapter 6, including the convective and stable cases over homogeneous land, the marine ABL and the internal boundary layer at the coastline. Chapter 7 then extends the discussion to the cloudy ABL. This is seen as particularly relevant, since the extensive stratocumulus regions over the subtropical oceans and stratus regions over the Arctic are now identified as key players in the climate system. Finally, chapters 8 and 9 bring much of the book's material together in a discussion of appropriate ABL and surface parameterization schemes in general circulation models of the atmosphere that are being used for climate simulation.

Download or read book Simulations of Neutral Atmospheric Boundary Layer Flow Over Complex Terrain with Comparisons to Field Measurements written by Yi Han and published by . This book was released on 2019 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work establishes a complete process to perform the micro-scale simulations of the neutral atmospheric boundary layer (ABL) flow over realistic terrain with multi-fidelity turbulence modeling approaches, and to validate the numerical predictions with the available on-site wind data. The complex terrain is located within the Chokecherry and Sierra Madre wind farm site which encompasses about 500 square kilometers of rugged and diverse terrain in south-central Wyoming. A robust conditional sampling procedure for the meteorological tower (met-tower) data to identify near-neutral ABL condition based on a criterion of the turbulence intensity is developed. The conditionally averaged wind data on fourteen met-towers is used for the model validation. The ABL flow simulations are conducted based on the OpenFOAM-based simulator for on/offshore wind farm applications (SOWFA) with both RANS and LES turbulence modeling approaches. The turbulent inflow is generated through a two-stage iterative approach using a precursor method. Appropriate boundary conditions are developed to adjust the real flow patterns over the complex terrain. In the RANS approach, a new formulation to calculate the production term in the transport equation for the turbulent kinetic energy (TKE) is developed to greatly reduce the commonly observed nonphysical near-surface TKE peak, and to improve the prediction of law-of-the-wall scaling in the near-surface region. In the LES approach, a low-dissipative, scale-selective discretization scheme is applied to the non-linear convection term of the filtered momentum equation. The aim is to reduce the numerical dissipation arising from the typically adopted upwind-biased schemes while maintaining second-order accuracy. The simulation results from both RANS and LES approaches are qualitatively compared with each other, and quantitatively compared to the conditional met-tower data in terms of the mean, standard deviation and direction of the wind at three about ground levels. The instantaneous flow field and turbulent structures are predicted by the LES approach. Overall, the wind statistic obtained by RANS and LES approaches show reasonable agreement compared to the met-tower data, except for some under-predictions at four met-tower located closer to the main ridge of the hill in a region of strong terrain variations.

Download or read book The Neutral Atmospheric Boundary Layer Over Complex Terrain written by William Peter Kustas and published by . This book was released on 1983 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Atmospheric Processes over Complex Terrain written by William Blumen and published by Springer. This book was released on 2016-06-30 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of the American Meteorological Society are "the development and dissemination of knowledge of meteorology in all its phases and applications, and the advancement of its professional ideals." The organization of the Society took place in affiliation with the American Association for the Advancement of Science at Saint Louis, Missouri, December 29, 1919, and its incorporation, at Washington, D. C., January 21, 1920. The work of the Society is carried on by the Bulletin, the Journal, and Meteorological Monographs, by papers and discussions at meetings of the Society, through the offices of the Secretary and the Executive Secretary, and by correspondence. All of the Americas are represented in the membership of the Society as well as many foreign countries.

Download or read book Soil Moisture in Complex Terrain written by Megan Hanako Daniels and published by . This book was released on 2010 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Soil moisture affects flow in the atmospheric boundary layer (ABL) through relative partitioning of surface energy fluxes. Surface conditions significantly affect flow in the ABL under quiescent synoptic conditions (weak forcing) over flat terrain, but strong wind forcing often dominates land surface effects. Over complex terrain, it is unclear what role soil moisture plays. Due to a lack of data at the appropriate resolution, surface conditions are often interpolated from coarse grids as part of a standard intialization procedure for mesoscale atmospheric models. In this work, simulations of the ABL are performed using the Advanced Regional Prediction System (ARPS) in a horizontally nested grid configuration for the complex terrain of Owens Valley, California, site of the Terrain-Induced Rotor Experiment (T-REX) in March and April, 2006. Effects of surface conditions on simulations of ABL flow in complex terrain under both weak and strong synoptic forcing are investigated through a sensitivity study and through comparisons to observations. Coupled hydrologic modeling using PF. CLM, a coupled groundwater-land-surface model, is presented as a physically-based alternative to standard initialization procedures. Soil moisture measurements were carried out during T-REX and are used to validate results of the coupled hydrologic modeling. Results of the sensitivity study indicate that simulations of the ABL are sensitive to surface soil moisture initialization under both weak and strong synoptic forcing. Comparisons of simulation results to observations show significant improvements in most simulations with more accurate soil moisture. Coupled hydrologic modeling is a promising alternative to standard initialization procedures; even simple two-dimensional simulations successfully capture soil moisture trends across Owens Valley. Simple adjustments to standard initial soil moisture based on field observations yield significant improvements in comparisons to observations as well.

Download or read book Immersed Boundary Methods for High Resolution Simulation of Atmospheric Boundary Layer Flow Over Complex Terrain written by Katherine Ann Lundquist and published by . This book was released on 2010 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mesoscale models, such as the Weather Research and Forecasting (WRF) model, are increasingly used for high resolution simulations, particularly in complex terrain, but errors associated with terrain-following coordinates degrade the accuracy of the solution. Use of an alternative Cartesian gridding technique, known as an immersed boundary method (IBM), alleviates coordinate transformation errors and eliminates restrictions on terrain slope which currently limit mesoscale models to slowly varying terrain. In this dissertation, an immersed boundary method is developed for use in numerical weather prediction. Use of the method facilitates explicit resolution of complex terrain, even urban terrain, in the WRF mesoscale model. First, the errors that arise in the WRF model when complex terrain is present are presented. This is accomplished using a scalar advection test case, and comparing the numerical solution to the analytical solution. Results are presented for different orders of advection schemes, grid resolutions and aspect ratios, as well as various degrees of terrain slope. For comparison, results from the same simulation are presented using the IBM. Both two-dimensional and three-dimensional immersed boundary methods are then described, along with details that are specific to the implementation of IBM in the WRF code. Our IBM is capable of imposing both Dirichlet and Neumann boundary conditions. Additionally, a method for coupling atmospheric physics parameterizations at the immersed boundary is presented, making IB methods much more functional in the context of numerical weather prediction models. The two-dimensional IB method is verified through comparisons of solutions for gentle terrain slopes when using IBM and terrain-following grids. The canonical case of flow over a Witch of Agnesi hill provides validation of the basic no-slip and zero gradient boundary conditions. Specified diurnal heating in a valley, producing anabatic winds, is used to validate the use of flux (non-zero) boundary conditions. This anabatic flow set-up is further coupled to atmospheric physics parameterizations, which calculate surface fluxes, demonstrating that the IBM can be coupled to various land-surface parameterizations in atmospheric models. Additionally, the IB method is extended to three dimensions, using both trilinear and inverse distance weighted interpolations. Results are presented for geostrophic flow over a three-dimensional hill. It is found that while the IB method using trilinear interpolation works well for simple three-dimensional geometries, a more flexible and robust method is needed for extremely complex geometries, as found in three-dimensional urban environments. A second, more flexible, immersed boundary method is devised using inverse distance weighting, and results are compared to the first IBM approach. Additionally, the functionality to nest a domain with resolved complex geometry inside of a parent domain without resolved complex geometry is described. The new IBM approach is used to model urban terrain from Oklahoma City in a one-way nested configuration, where lateral boundary conditions are provided by the parent domain. Finally, the IB method is extended to include wall model parameterizations for rough surfaces. Two possible implementations are presented, one which uses the log law to reconstruct velocities exterior to the solid domain, and one which reconstructs shear stress at the immersed boundary, rather than velocity. These methods are tested on the three-dimensional canonical case of neutral atmospheric boundary layer flow over flat terrain.

Download or read book Characterisation of the Atmospheric Boundary Layer in a Complex Terrain Using SODAR RASS written by Jens-Christopher Mayer and published by . This book was released on 2005 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modeling Wind Distributions Over Complex Terrain written by Mark A. Yocke and published by . This book was released on 1979 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book European Wind Atlas written by Ib Troen and published by . This book was released on 1989 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt: Beskriver resultatet af et europæisk samarbejde inden for EU vedr. vindenergiens udnyttelse ved at beskrive vindressourcen og de forskellige terraintypers indflydelse herpå.

Download or read book Characterization of the Atmospheric Boundary Layer in Complex Terrain and Results from the AMADEUS Dispersion Experiments written by David Fleming Brown and published by . This book was released on 1992 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Subfilter scale Turbulence Modeling for Large eddy Simulation of the Atmospheric Boundary Layer Over Complex Terrain written by Fotini Katopodes Chow and published by . This book was released on 2004 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: