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 Numerical and Observational Study of the Genesis of Concentric Eyewall Hurricanes written by Shangyao Nong and published by . This book was released on 1999 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Convectively generated Potential Vorticity in Rainbands and Secondary Eyewall Formation in Hurricanes written by Falko Judt and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Concentric eyewall formation and eyewall replacement cycles are intrinsic processes that determine the intensity of a tropical cyclone, as opposed to purely environmental factors such as wind shear or the ocean heat content. Although extensive research has been done in this area, there is not a single widely accepted theory on the formation of secondary eyewall structures. Many previous studies focused on dynamic processes in the inner core of a tropical cyclone that would precede and ultimately lead to the formation of a secondary eyewall. Hurricanes Katrina and Rita in 2005 were frequently sampled by research aircraft which gathered a copious amount of data. During this time, Rita developed a secondary eyewall which eventually replaced the original eyewall. This thesis will investigate the formation of a secondary eyewall with particular emphasis on the rainband region, as observations show that an outer principal rainband transformed into the secondary ring. A high resolution, full physics model (MM5) initialized with global model forecast fields correctly predicted the secondary eyewall formation in Rita. The model output will be used to investigate both Katrina and Rita in terms of their PV generation characteristics since PV and vorticity maxima correlate well with wind maxima that accompany the eyewall and rainbands. Furthermore, dynamical processes such as vortex Rossby wave (VRW) activity in the inner core region will be analyzed. Comparison of the differences in the two storms might shed some light on dynamics that can lead to structure changes. Comparison of the model data with aircraft observation is used to validate the results. Doppler radar derived wind fields will be used to calculate the vertical vorticity. The vorticity field is closely related to PV and thus a manifestation of the PV generation process in the rainband. The investigation has shown that Rita2s principal rainband features higher PV generation rates at radii beyond 80 km. Both the azimuthal component and the projection of asymmetric PV generated by convection onto the azimuthal mean connected with the principal band are hypothesized to be of importance for the formation of the secondary eyewall. VRW were found not to be important for the initial formation of the ring but might enhance convective activity once the outer eyewall contracts.

Download or read book Impacts of Asymmetric Dynamics on Tropical Cyclone Eyewall Replacement Cycles written by Tsz Kin Lai and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "In mature tropical cyclones (TCs), secondary eyewall formation (SEF) is a frequently observed feature associated with the formation of an outer (secondary) eyewall outside the existing (primary) eyewall. The two eyewalls are separated by a moat region of convective minimum and vorticity minimum. An SEF is often followed by an eyewall replacement cycle (ERC) during which the contracting outer eyewall gradually intensifies while the inner eyewall dissipates. Throughout this period, significant changes in the size and the intensity of the TC usually occur. Therefore, a better understanding of ERC is desired for better TC forecasts. Nevertheless, the mechanisms underlying inner eyewall decay (IED) and outer eyewall intensification (OEI) are not well-understood. It is widely accepted that the cutoff effect associated with the OE makes the main contribution to the IED. However, radar imagery of some double-eyewall TCs showed that the TC vortices became elliptic prior to and during the IED. This kind of elliptic development could result from the dynamic (barotropic) instability across the moat, which is a region of sign reverse of vorticity gradient and satisfies the Rayleigh necessary condition for barotropic instability. Hence, the instability across the moat (known as the type-2 instability) may also make contributions to IED. As the first part of the thesis (Chapter 2), a study of the simulated Hurricane Wilma (2005) is conducted by using a three-dimensional (3D) cloud-resolving full-physics numerical model. It is found that the timing of the onset of the type-2 instability is coincident with the start of the rapid decrease of the low-level IE circulation, indicating that the circulation of the IE is likely weakened by the vorticity mixing associated with the type-2 instability. In the second part of the thesis (Chapter 3), two 3D numerical experiments are performed to further explore the underlying dynamics. The detailed budget analyses of azimuthally averaged absolute angular momentum (AAM) in the moist full-physics experiment clearly show that the eddy radial flux of vorticity associated with the type-2 instability makes significant contributions to the decrease in AAM of the IE and the increase in AAM of the OE. It is also found that the type-2 instability can work with the cutoff effect to accelerate the IED process. Similar patterns of the AAM budget analyses are also obtained from the dry experiment in which all physics parameterisation schemes are switched off. It is thus suggested that the type-2 instability is a fundamental process responsible for the IED and OEI in these two experiments. In the third part of the thesis (Chapter 4), unforced shallow water (SW) experiments further reveal that the intensity changes in the eyewalls through the eddy radial flux of vorticity are intrinsic nonlinear features of the type-2 instability. In addition, a detailed analysis of the most unstable eigenmode of a double-eyewall TC-like vortex shows evidence of substantial divergence of angular momentum flux over the IE and significant convergence of angular momentum flux over the OE. This further demonstrates that the origin of the intensity changes of the eyewalls is the angular momentum transport from the IE to the OE by the eddy processes associated with the type-2 instability. The last part of the thesis (Chapter 5) discusses the long-term effect of the type-2 instability on the eyewall intensity changes during ERCs. A series of forced and unforced SW experiments, which are initialised with different parameters of the vortex and convective heating, show repeated cycles of decay-intensification after the type-2 instability has been excited for a longer time. It is found that the oscillation results from the periodic elongation and contraction of the vortices associated with the long-term nonlinear evolution of the type-2 instability. These results suggest that predicting the eyewall intensity changes during ERCs may be a challenge"--

Download or read book Asymmetries During Eyewall Replacement Cycles of Hurricane Ivan 2004 written by Bruno Rojas and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Eyewall replacement cycles (ERCs) are a frequently occurring phenomenon in tropical cyclones (TCs) that can significantly affect both the structure and intensity of TCs. The physical processes that govern the evolution of different stages of an ERC are not yet fully understood. In particular, asymmetric structures within the TC inner core are complex features with an uncertain role ERC dynamics. To help fill these gaps in understanding, this study analyzes the kinematic and precipitation asymmetric structures during successive ERCs in Hurricane Ivan (2004) using airborne Doppler radar observations. The azimuthal location of these asymmetries are analyzed relative to the deep-layer (850-200 hPa) environmental wind shear vector. During the first ERC stage (secondary eyewall onset), the developing secondary eyewall region exhibited a defined convective rainband in the right-of-shear half where the strongest updrafts and reflectivities occurred. The left-of-shear half exhibited more stratiform precipitation, consistent with properties of a shear-aligned rainband complex that often precedes SEF events. During the second ERC stage (concentric eyewall period), the outer eyewall updrafts were strongest in the left-of-shear half. These updrafts were collocated with mesoscale descending inflow (MDI) and was downwind of an inward spiraling low-level convergence zone in the downshear quadrants. These observations suggest that the updrafts (and resulting vertical velocity asymmetry) were likely forced by a stratiform-induced cold pool in a similar manner to MDI impacts seen in past studies. During the final ERC stage (post-replacement adjustment), the outer eyewall (now the singular primary eyewall) experienced an upwind shift in the precipitation and vertical velocity asymmetries. The updraft maximum shifted from the downshear-left quadrant to the downshear-right quadrant, and the precipitation maximum (downwind of the updraft maximum) shifted from left-of-shear to the downshear direction. This shift corroborates previous studies, which suggest that at the end of an ERC, the asymmetric forcing mechanism that drives the eyewall updraft maximum transitions from MDI/cold pool processes to direct interaction with the environmental wind shear. Results of this study will further understanding of the changing asymmetries and underlying dynamics during ERCs.

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 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Atmospheric Science written by John M. Wallace and published by Elsevier. This book was released on 2006-03-24 with total page 507 pages. Available in PDF, EPUB and Kindle. Book excerpt: Atmospheric Science, Second Edition, is the long-awaited update of the classic atmospheric science text, which helped define the field nearly 30 years ago and has served as the cornerstone for most university curricula. Now students and professionals alike can use this updated classic to understand atmospheric phenomena in the context of the latest discoveries, and prepare themselves for more advanced study and real-life problem solving. This latest edition of Atmospheric Science, has been revamped in terms of content and appearance. It contains new chapters on atmospheric chemistry, the Earth system, the atmospheric boundary layer, and climate, as well as enhanced treatment of atmospheric dynamics, radiative transfer, severe storms, and global warming. The authors illustrate concepts with full-color, state-of-the-art imagery and cover a vast amount of new information in the field. Extensive numerical and qualitative exercises help students apply basic physical principles to atmospheric problems. There are also biographical footnotes summarizing the work of key scientists, along with a student companion website that hosts climate data; answers to quantitative exercises; full solutions to selected exercises; skew-T log p chart; related links, appendices; and more. The instructor website features: instructor’s guide; solutions to quantitative exercises; electronic figures from the book; plus supplementary images for use in classroom presentations. Meteorology students at both advanced undergraduate and graduate levels will find this book extremely useful. Full-color satellite imagery and cloud photographs illustrate principles throughout Extensive numerical and qualitative exercises emphasize the application of basic physical principles to problems in the atmospheric sciences Biographical footnotes summarize the lives and work of scientists mentioned in the text, and provide students with a sense of the long history of meteorology Companion website encourages more advanced exploration of text topics: supplementary information, images, and bonus exercises

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 Environmental and Internal Controls of Tropical Cyclones Intensity Change written by Melicie Desflots and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Tropical cyclone (TC) intensity change is governed by internal dynamics (e.g. eyewall contraction, eyewall replacement cycles, interactions of the inner-core with the rainbands) and environmental conditions (e.g. vertical wind shear, moisture distribution, and surface properties). This study aims to gain a better understanding of the physical mechanisms responsible for TC intensity changes with a particular focus to those related to the vertical wind shear and surface properties by using high resolution, full physics numerical simulations. First, the effects of the vertical wind shear on a rapidly intensifying storm and its subsequent weakening are examined. Second, a fully coupled atmosphere-wave-ocean model with a sea spray parameterization is used to study the impact of sea spray on the hurricane boundary layer. The coupled model consists of three components: the high resolution, non-hydrostatic, fifth generation Pennsylvania State University-NCAR mesoscale model (MM5), the NOAA/NCEPWAVEWATCH III (WW3) ocean surface wave model, and theWHOI threedimensional upper ocean circulation model (3DPWP). Sea spray parameterizations were developed at NOAA/ESRL and modified by the author to be introduced in uncoupled and coupled simulations. The model simulations are conducted in both uncoupled and coupled modes to isolate various physical processes influencing TC intensity. The very high-resolutionMM5 simulation of Hurricane Lili (at 0.5 km grid resolution) showed a rapid intensification associated with a contracting eyewall. Changes in both the magnitude and the direction of the vertical wind shear associated with an approaching upper-tropospheric trough were responsible for the weakening of the storm before landfall. Hurricane Lili weakened in a 5-10 m/s vertical wind shear environment. The simulated storm experienced wind shear direction normal to the storm motion, which produced a strong wavenumber one rainfall asymmetry in the downshear-left quadrant of the storm. The rainfall asymmetry was confirmed by various observations from the TRMM satellite and the WSR-88D ground radar in the coastal region. The increasing vertical wind shear induced a vertical tilt of the vortex with a time lag of about 5-6 hours after the wavenumber one rainfall asymmetry was first observed in the model simulation. Other key factors controlling intensity and intensity change in tropical cyclones are the air-sea fluxes. Accurate measurement and parameterization of air-sea fluxes under hurricane conditions are challenging. Although recent studies have shown that the momentum exchange coefficient levels off at high wind speed, little is known about the high wind behavior of the exchange coefficient for enthalpy flux. One of the largest uncertainties is the potential impact of sea spray. The current sea spray parameterizations are closely tied to wind speed and tend to overestimate the mediated heat fluxes by sea spray in the hurricane boundary layer. The sea spray generation depends not only on the wind speed but also on the variable wave state. A new spray parameterization based on the surface wave energy dissipation is introduced in the coupled model. In the coupled simulations, the wave energy dissipation is used to quantify the amount of wave breaking related to the generation of sea spray. The spray parameterization coupled to the waves may be an improvement compared to sea spray parameterizations that depends on wind speed only.

Download or read book Dynamics and Predictability of Large Scale High Impact Weather and Climate Events written by Jianping Li and published by Cambridge University Press. This book was released on 2016-03-24 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the dynamical processes between high-impact weather and climate events, and between atmospheric and ocean phenomena.

Download or read book The Representation of Cumulus Convection in Numerical Models written by Kerry Emanuel and published by Springer. This book was released on 2015-03-30 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents descriptions of numerical models for testing cumulus in cloud fields. It is divided into six parts. Part I provides an overview of the problem, including descriptions of cumulus clouds and the effects of ensembles of cumulus clouds on mass, momentum, and vorticity distributions. A review of closure assumptions is also provided. A review of "classical" convection schemes in widespread use is provided in Part II. The special problems associated with the representation of convection in mesoscale models are discussed in Part III, along with descriptions of some of the commonly used mesoscale schemes. Part IV covers some of the problems associated with the representation of convection in climate models, while the parameterization of slantwise convection is the subject of Part V.

Download or read book Effects of Environmental Water Vapor on Tropical Cyclone Structure and Intensity written by Derek Ortt and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Water vapor not only affects TC intensity. Prior modeling studies have demonstrated impacts from environmental water vapor on TC structure. These impacts can also affect intensity change. Specifically, enhanced water vapor content within the TC enhances the rainbands, which can lead to an eyewall replacement cycle, causing a temporary weakening, followed by re-intensification. This thesis evaluates observational and high resolution MM5 model output from Hurricanes Katrina and Rita from the Hurricane Rainband and Intensity Experiment (RAINEX) to evaluate the effects of varying water vapor distributions on TC structure. While the two hurricanes were of similar intensity, they had different water vapor distributions and structures. Rita underwent an eyewall replacement cycle while under RAINEX surveillance while Katrina did not. Rita was also located within a dry environment and had a strong horizontal moisture gradient, while Katrina was in a moist environment and had a weak moisture gradient. Results suggest that a strong horizontal water vapor gradient, with a moist TC and dry outer environment may confine the hurricanes into a pattern that causes them to have high circularity, promoting the formation of a secondary eyewall. The dry outer environment had strong atmospheric stability and was less favorable for deep convection far from the center in the Rita case. The moist environment in the Katrina case was more unstable. This may have allowed for the rainbands to be farther from the center in a less circular pattern than Rita. The results presented in this thesis suggest that this pattern is less favorable for an eyewall replacement cycle.

Download or read book Integrating Social and Behavioral Sciences Within the Weather Enterprise written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2018-01-05 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our ability to observe and forecast severe weather events has improved markedly over the past few decades. Forecasts of snow and ice storms, hurricanes and storm surge, extreme heat, and other severe weather events are made with greater accuracy, geographic specificity, and lead time to allow people and communities to take appropriate protective measures. Yet hazardous weather continues to cause loss of life and result in other preventable social costs. There is growing recognition that a host of social and behavioral factors affect how we prepare for, observe, predict, respond to, and are impacted by weather hazards. For example, an individual's response to a severe weather event may depend on their understanding of the forecast, prior experience with severe weather, concerns about their other family members or property, their capacity to take the recommended protective actions, and numerous other factors. Indeed, it is these factors that can determine whether or not a potential hazard becomes an actual disaster. Thus, it is essential to bring to bear expertise in the social and behavioral sciences (SBS)â€"including disciplines such as anthropology, communication, demography, economics, geography, political science, psychology, and sociologyâ€"to understand how people's knowledge, experiences, perceptions, and attitudes shape their responses to weather risks and to understand how human cognitive and social dynamics affect the forecast process itself. Integrating Social and Behavioral Sciences Within the Weather Enterprise explores and provides guidance on the challenges of integrating social and behavioral sciences within the weather enterprise. It assesses current SBS activities, describes the potential value of improved integration of SBS and barriers that impede this integration, develops a research agenda, and identifies infrastructural and institutional arrangements for successfully pursuing SBS-weather research and the transfer of relevant findings to operational settings.

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 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 Issues in Global Environment Climate and Climate Change 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-05-01 with total page 1117 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Global Environment—Climate and Climate Change: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Climate Research. The editors have built Issues in Global Environment—Climate and Climate Change: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Climate Research in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Global Environment—Climate and Climate Change: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Hurricanes written by Paul V. Kislow and published by Nova Publishers. This book was released on 2008 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hurricane is a tropical storm with winds that have reached a constant speed of 74 miles per hour or more. Hurricane winds blow in a large spiral around a relative calm centre known as the "eye." The "eye" is generally 20 to 30 miles wide, and the storm may extend outward 400 miles. As a hurricane approaches, the skies will begin to darken and winds will grow in strength. As a hurricane nears land, it can bring torrential rains, high winds, and storm surges. A single hurricane can last for more than 2 weeks over open waters and can run a path across the entire length of the eastern seaboard. August and September are peak months during the hurricane season that lasts from 1 June to 30 November. This book presents the facts and history of hurricanes.