Download or read book Sensitivity of Simulated Hurricane Eyewall Replacement Cycles to Horizontal Turbulent Mixing written by Joanne Michelle Kennell and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Eyewall replacement cycles (ERCs) are naturally occurring phenomena in some intense tropical cyclones. The exact mechanisms of ERCs are currently not known and successful numerical simulations of ERCs are also rare. The objectives of this thesis are to 1) validate the current ERC theories for a set of numerical simulations which resolved ERC processes, 2) investigate the role of boundary layer turbulence in ERCs, and 3) propose a mechanism for ERCs. Using the Advanced Research and Weather Forecasting (WRF-ARW) model, Hurricane Danielle (2010) was simulated. The ERCs that occurred in simulated Danielle are sensitive to parameterized horizontal turbulent mixing. Five theories on the initiating mechanisms of eyewall replace cycles are discussed with respect to each of our simulations and based on the results, a new idea of how the eyewall replacement process formed in our simulations is proposed. Two sensitivity experiments are performed to test the validity of this mechanism.
Download or read book Investigation and Prediction of Hurricane Eyewall Replacement Cycles written by and published by . This book was released on 2012 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Numerical Modeling and Data Assimilation Techniques for Tropical Cyclone Predictions written by U.C. Mohanty and published by Springer. This book was released on 2016-11-21 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals primarily with monitoring, prediction and understanding of Tropical Cyclones (TCs). It was envisioned to serve as a teaching and reference resource at universities and academic institutions for researchers and post-graduate students. It has been designed to provide a broad outlook on recent advances in observations, assimilation and modeling of TCs with detailed and advanced information on genesis, intensification, movement and storm surge prediction. Specifically, it focuses on (i) state-of-the-art observations for advancing TC research, (ii) advances in numerical weather prediction for TCs, (iii) advanced assimilation and vortex initialization techniques, (iv) ocean coupling, (v) current capabilities to predict TCs, and (vi) advanced research in physical and dynamical processes in TCs. The chapters in the book are authored by leading international experts from academic, research and operational environments. The book is also expected to stimulate critical thinking for cyclone forecasters and researchers, managers, policy makers, and graduate and post-graduate students to carry out future research in the field of TCs.
Download or read book Sensitivity of WRF Simulations of Hurricane Ivan to Horizontal Resolution written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As finer resolutions become possible in numerical modeling, it has become increasingly common to turn off the cumulus parameterization scheme in favor of explicit simulation of convection. To the author's knowledge, the grid spacing at which it is appropriate to do so in a tropical cyclone (TC) case has not been systematically investigated. Therefore, this study examines the sensitivity of explicit model simulations of Hurricane Ivan (2004) to changes in horizontal grid spacing, when grid spacing between 12 and 2 km is used. As grid spacing decreases, the minimum central pressure of Ivan deepens, dropping by approximately 20 hPa as grid spacing decreases from 4 to 2 km. However, the 8-, 6-, and 4-km simulations have intensity differences of only around 10 hPa between them. The structure shown by model-simulated radar, as well as model-simulated satellite infra-red (IR) temperatures, shows that the eyewall of the coarser resolution simulations (12- to 6-km) is highly asymmetrical and elliptically-shaped, with two large maxima (minima) in reflectivity (cloud top temperature) rotating about the TC center. The 4- and 2-km runs have more circular eyewalls, with more numerous and larger maxima (minima) in reflectivity (cloud top temperature) embedded within the eyewall, as well as better developed spiral bands. Temporal and spatial averaging, done at a given radius over azimuth, show the system-averaged quanitites in cross-section and reveal differences in the structure of the TC core and eyewall. The finer resolution simulations have larger updrafts and more subsidence within the eye. However, the warming of the eye, relative to the other runs, is confined to the upper levels of the troposphere. The eyewall of the TC in the finer resolution runs slopes radially outward less with height, as the horizontal temperature gradient changes little with height, compared with the coarser simulations. This lack of warming in the lower- and mid-levels of the TC eye indicates a venti.
Download or read book Turbulent Characteristics in the Hurricane Boundary Layer written by Sunwei Li and published by . This book was released on 2012 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the medium between the sea surface and the upper atmosphere in a hurricane, the Hurricane Boundary Layer (HBL) plays a key role in the overall dynamics of a tropical cyclone, and therefore turbulence exchanges within the HBL deserve a thorough investigation. However, since it is dangerous and difficult to take direct measurements within the HBL, studies of the HBL turbulence processes based on direct observations are rare. Thanks to the newly developed dropwindsonde equipped with a Global Position System (GPS) receiver, it is now possible to measure wind velocities and other meteorological variables with an unprecedented accuracy and resolution in the HBL. To fully utilize dropwindsonde measurements, it is necessary to thoroughly understand its motion characteristics in the measured wind field since its horizontal motions are usually reported as wind measurements. For that reason, the dropwindsonde motion in a pseudo-stochastic wind field with known statistics is simulated. The simulation results illustrate the importance of the wind finding equations introduced by Hock and Franklin (1999) which calculate local winds from dropwindsonde motions. The simulation results show that they are important in reproducing both mean and turbulent wind structures in the HBL. One of its basic assumptions that the dropwindsonde drag coefficient is a constant regardless of the angle of attack is, however, invalidated by the wind tunnel tests conducted in this study. Given that this assumption is essential in both deriving the wind finding equations and in conducting the numerical dropwindsonde motion simulation described above, it is necessary to adapt the dropwindsonde motion model and to repeat the motion simulation to recheck the validity of the wind finding equations demonstrated in the previous simulation. The results validates the wind finding equations although it is derived based on a false assumption that the dropwindsonde drag coefficient is a constant regardless of angles of attack. Moreover, through analyzing the adapted dropwindsonde motion model, a new approach to estimate the vertical wind is proposed which is shown to increase the accuracy in vertical wind estimation by nearly 70%. Based on the findings derived in the dropwindsonde motion simulations, an in-house software package is designed to process the actual dropwindsonde measurements gathered from 1997 to 2010. The in-house software package, showing an effectiveness equivalent to other widely used processing systems, gives users more control over the processing and compositing procedures used to derive the desired statistics of the measured wind field. With the help of this software package, dropwindsonde measurements are processed and composited to produce the mean, turbulence intensity, and turbulent length scale profiles of the HBL. While the mean wind structure confirms the findings made by several previous studies, the turbulence structure reveals that the turbulence diffusivity formulation currently used by the Yonsei University planetary boundary layer scheme, or the YSU scheme, in Weather Research and Forecasting Model(WRF), a widely used hurricane wind simulation package, correctly simulate turbulent mixing in the HBL up to 200m from the sea surface. In a theoretical discussion of the validity of the YSU scheme, it is found that both the velocity scale and height scale used in its turbulence diffusivity formulation should be revised to take into consideration the special turbulence characteristics in the HBL. For the purpose of checking the turbulence diffusivity formulation used in the YSU scheme, high resolution numerical simulations of an idealized tropical cyclone are conducted using WRF. The simulation results show that only revising the HBL height calculation is not adequate to improve the numerical simulation of hurricanes. Therefore, a deeper investigation of the YSU scheme in simulating the HBL turbulence is required.
Download or read book Analysis of Environmental Factors Contributing to the Eyewall Replacement Cycle of Hurricanes written by Martha Christino and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Even the most advanced hurricane forecast models have difficulty predicting eyewall replacement cycles (ERCs) in tropical cyclones. Most research has attempted to solve this problem by working to understand the dynamic and kinematic drivers of an ERC. This project proposes an alternative approach focused on analyzing the changes in measurable environmental factors and utilizing a machine learning algorithm to predict the ERC. The aim of the first phase of this project is to establish which environmental factors are linked to the initial development of a secondary eye wall. Thirty-seven occurrences of secondary eyewall formation (SEF) in hurricanes between 1984 and 2018 were selected based on the criteria used in Sitkowski, et al. (2011). Each SEF event was matched with a similarly intensifying hurricane that did not experience a subsequent SEF event based on the year and storm intensity. Using environmental data from the Statistical Hurricane Intensity Prediction Scheme (SHIPS) predictor files, the change in each environmental variable at six-hour intervals for twenty-four hours before the start of SEF was analyzed. The environmental variables that experience the most significant change prior to SEF will determine which variables should be used as predictors in a machine learning program designed to predict SEF onset. The goal of this research is to create an algorithm capable of predicting a SEF event twenty-four hours in advance. This algorithm will be compared to existing statistical SEF prediction schemes. Predicting ERC events will allow hurricane track and intensity models to produce more accurate forecasts and emergency response centers to accordingly alter evacuation zones, resulting in decreased economic loss and fatalities.
Download or read book A Study on the Turbulent Characteristics Within the Hurricane Boundary Layer written by Sunwei Li and published by . This book was released on 2012 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the medium between the sea surface and the upper atmosphere in a hurricane, the Hurricane Boundary Layer (HBL) plays a key role in the overall dynamics of a tropical cyclone, and therefore turbulence exchanges within the HBL deserve a thorough investigation. However, since it is dangerous and difficult to take direct measurements within the HBL, studies of the HBL turbulence processes based on direct observations are rare. Thanks to the newly developed dropwindsonde equipped with a Global Position System (GPS) receiver, it is now possible to measure wind velocities and other meteorological variables with an unprecedented accuracy and resolution in the HBL. To fully utilize dropwindsonde measurements, it is necessary to thoroughly understand its motion characteristics in the measured wind field since its horizontal motions are usually reported as wind measurements. For that reason, the dropwindsonde motion in a pseudo-stochastic wind field with known statistics is simulated. The simulation results illustrate the importance of the wind finding equations introduced by Hock and Franklin (1999) which calculate local winds from dropwindsonde motions. The simulation results show that they are important in reproducing both mean and turbulent wind structures in the HBL. One of its basic assumptions that the dropwindsonde drag coefficient is a constant regardless of the angle of attack is, however, invalidated by the wind tunnel tests conducted in this study. Given that this assumption is essential in both deriving the wind finding equations and in conducting the numerical dropwindsonde motion simulation described above, it is necessary to adapt the dropwindsonde motion model and to repeat the motion simulation to recheck the validity of the wind finding equations demonstrated in the previous simulation. The results validates the wind finding equations although it is derived based on a false assumption that the dropwindsonde drag coefficient is a constant regardless of angles of attack. Moreover, through analyzing the adapted dropwindsonde motion model, a new approach to estimate the vertical wind is proposed which is shown to increase the accuracy in vertical wind estimation by nearly 70%. Based on the findings derived in the dropwindsonde motion simulations, an in-house software package is designed to process the actual dropwindsonde measurements gathered from 1997 to 2010. The in-house software package, showing an effectiveness equivalent to other widely used processing systems, gives users more control over the processing and compositing procedures used to derive the desired statistics of the measured wind field. With the help of this software package, dropwindsonde measurements are processed and composited to produce the mean, turbulence intensity, and turbulent length scale profiles of the HBL. While the mean wind structure confirms the findings made by several previous studies, the turbulence structure reveals that the turbulence diffusivity formulation currently used by the Yonsei University planetary boundary layer scheme, or the YSU scheme, in Weather Research and Forecasting Model(WRF), a widely used hurricane wind simulation package, correctly simulate turbulent mixing in the HBL up to 200m from the sea surface. In a theoretical discussion of the validity of the YSU scheme, it is found that both the velocity scale and height scale used in its turbulence diffusivity formulation should be revised to take into consideration the special turbulence characteristics in the HBL. For the purpose of checking the turbulence diffusivity formulation used in the YSU scheme, high resolution numerical simulations of an idealized tropical cyclone are conducted using WRF. The simulation results show that only revising the HBL height calculation is not adequate to improve the numerical simulation of hurricanes. Therefore, a deeper investigation of the YSU scheme in simulating the HBL turbulence is required.
Download or read book Boundary Layer Dynamics written by National Research Council and published by National Academies Press. This book was released on 1997-04-24 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Automated Surface Observing System written by and published by . This book was released on 1998 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Introduction to Boundary Layer Meteorology written by Roland B. Stull and published by Springer Science & Business Media. This book was released on 1988-07-31 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt: Part of the excitement in boundary-layer meteorology is the challenge associated with turbulent flow - one of the unsolved problems in classical physics. An additional attraction of the filed is the rich diversity of topics and research methods that are collected under the umbrella-term of boundary-layer meteorology. The flavor of the challenges and the excitement associated with the study of the atmospheric boundary layer are captured in this textbook. Fundamental concepts and mathematics are presented prior to their use, physical interpretations of the terms in equations are given, sample data are shown, examples are solved, and exercises are included. The work should also be considered as a major reference and as a review of the literature, since it includes tables of parameterizatlons, procedures, filed experiments, useful constants, and graphs of various phenomena under a variety of conditions. It is assumed that the work will be used at the beginning graduate level for students with an undergraduate background in meteorology, but the author envisions, and has catered for, a heterogeneity in the background and experience of his readers.
Download or read book Climatological Atlas of the World Ocean written by Sydney Levitus and published by . This book was released on 1982 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electric Melting and Holding Furnaces in the Ironfounding Industry written by and published by . This book was released on 1968 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Introduction to Dynamic Meteorology written by James R. Holton and published by Academic Press. This book was released on 1979 with total page 409 pages. Available in PDF, EPUB and Kindle. Book excerpt: For advanced undergraduate and beginning graduate students in atmospheric, oceanic, and climate science, Atmosphere, Ocean and Climate Dynamics is an introductory textbook on the circulations of the atmosphere and ocean and their interaction, with an emphasis on global scales. It will give students a good grasp of what the atmosphere and oceans look like on the large-scale and why they look that way. The role of the oceans in climate and paleoclimate is also discussed. The combination of observations, theory and accompanying illustrative laboratory experiments sets this text apart by making it accessible to students with no prior training in meteorology or oceanography. * Written at a mathematical level that is appealing for undergraduates and beginning graduate students * Provides a useful educational tool through a combination of observations and laboratory demonstrations which can be viewed over the web * Contains instructions on how to reproduce the simple but informative laboratory experiments * Includes copious problems (with sample answers) to help students learn the material.
Download or read book Climate Intervention written by National Research Council and published by National Academies Press. This book was released on 2015-06-23 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: The growing problem of changing environmental conditions caused by climate destabilization is well recognized as one of the defining issues of our time. The root problem is greenhouse gas emissions, and the fundamental solution is curbing those emissions. Climate geoengineering has often been considered to be a "last-ditch" response to climate change, to be used only if climate change damage should produce extreme hardship. Although the likelihood of eventually needing to resort to these efforts grows with every year of inaction on emissions control, there is a lack of information on these ways of potentially intervening in the climate system. As one of a two-book report, this volume of Climate Intervention discusses albedo modification - changing the fraction of incoming solar radiation that reaches the surface. This approach would deliberately modify the energy budget of Earth to produce a cooling designed to compensate for some of the effects of warming associated with greenhouse gas increases. The prospect of large-scale albedo modification raises political and governance issues at national and global levels, as well as ethical concerns. Climate Intervention: Reflecting Sunlight to Cool Earth discusses some of the social, political, and legal issues surrounding these proposed techniques. It is far easier to modify Earth's albedo than to determine whether it should be done or what the consequences might be of such an action. One serious concern is that such an action could be unilaterally undertaken by a small nation or smaller entity for its own benefit without international sanction and regardless of international consequences. Transparency in discussing this subject is critical. In the spirit of that transparency, Climate Intervention: Reflecting Sunlight to Cool Earth was based on peer-reviewed literature and the judgments of the authoring committee; no new research was done as part of this study and all data and information used are from entirely open sources. By helping to bring light to this topic area, this book will help leaders to be far more knowledgeable about the consequences of albedo modification approaches before they face a decision whether or not to use them.
Download or read book Practical Meteorology written by Roland Stull and published by Sundog Publishing, LLC. This book was released on 2018 with total page 942 pages. Available in PDF, EPUB and Kindle. Book excerpt: A quantitative introduction to atmospheric science for students and professionals who want to understand and apply basic meteorological concepts but who are not ready for calculus.
Download or read book Crude Existence written by Kristin Reed and published by Univ of California Press. This book was released on 2009-11-15 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: After decades of civil war and instability, the African country of Angola is experiencing a spectacular economic boom thanks to its most valuable natural resource: oil. Focusing on the everyday realities of people living in the extraction zones, Reed explores the exclusion, degradation, and violence that are the fruits of petrocapitalism in Angola.
Download or read book Natural Disasters and Extreme Events in Agriculture written by Mannava VK Sivakumar and published by Springer Science & Business Media. This book was released on 2005-12-06 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: Agricultural production is highly sensitive to weather and climate-related disasters such as drought, storm and flood. While it is not possible to prevent the occurrence of natural disasters, the resultant disastrous effects can be reduced mitigated through proper planning and effective preparation. This book, based on a gathering of experts in Beijing, discusses ways to reduce the vulnerability of agriculture to disaster and extreme events, both by accurate and timely warning, and by impact-reducing countermeasures.
