Download or read book Generation of African Easterly Waves written by Jen-Shan Hsieh and published by . This book was released on 2005 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Generation of African Wave Disturbances written by Torsten Duffy and published by . This book was released on 2000 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Maintenance and Propagation of African Easterly Waves Across Northern Africa A Case Study and Analysis of the Environment written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research focuses on the formation and maintenance of an African Easterly Wave (AEW) that developed over Northern Africa in 2000. Specifically, the pre-development period of Hurricane Alberto that initially formed over the Ethiopian Highlands (EH) region is studied in conjunction with this AEW disturbance. Based on EUMETSAT infrared (IR) satellite imagery and ECMWF 0.5o observational model (EOM) analysis data, we identified four convective genesis periods (G-I, G-II, G-III, and G-IV) and three lysis periods (L-I, L-II, and L-III). Based on the EOM analysis of the pre-Alberto system, we found that moisture and vertical velocity played a major role in the generation and maintenance of the convective cycles associated with the pre-Alberto system as it traveled westward across Northern Africa. Initially, orographic effects induce vertical velocity and moisture, and as the Alberto system travels westward these parameters are governed more by environmental factors. The National Center for Atmospheric Research (NCAR) Regional Climate Model Version 3.0 (henceforth RegCM3) was used to run the control case and several sensitivity simulations. We found that the EH is important for focusing and organizing AEW features by producing a consistent stationary wave mode, generating lee side vorticity, and initially providing sufficient vertical moisture flux for convection. PBL effects over the EH cause the initial convection in response to diurnal diabetic heating. As this convection propagates downstream, it merges with the orographically generated MV on the lee of the EH and a MCC results. PBL effects and moisture availability are important for propagating and maintaining AEW disturbances as they travel to the west and supporting sufficient moisture by allowing for surface moisture fluxes to affect these systems and aid in convective development. The AEW is slightly modulated by orography downstream from the EH region. Both the EH region and the PBL effects are essential in th.
Download or read book The Generation Maintenance and Propagation of the Pre helene African Easterly Wave and Mesoscale Convective System Over Africa written by James Spinks and published by . This book was released on 2009 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigates the origin of the mesoscale convective system (MCS) and the African easterly wave (AEW) over the African continent which triggered hurricane Helene in 2006. Looks at the environmental factors that played a role in aiding the pre-Helene AEW-MCS as well as conducting an in-depth examination of the splitting-advecting-merging mechanism observed with the pre-Helene AEW-MCSs. Investigates the origin and propagation of the pre-Helene MCS and AEW by using satellite imagery and results simulated by the weather research and forecasting (WRF) model.
Download or read book Atmospheric and Oceanic Fluid Dynamics written by Geoffrey K. Vallis and published by Cambridge University Press. This book was released on 2006-11-06 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid dynamics is fundamental to our understanding of the atmosphere and oceans. Although many of the same principles of fluid dynamics apply to both the atmosphere and oceans, textbooks tend to concentrate on the atmosphere, the ocean, or the theory of geophysical fluid dynamics (GFD). This textbook provides a comprehensive unified treatment of atmospheric and oceanic fluid dynamics. The book introduces the fundamentals of geophysical fluid dynamics, including rotation and stratification, vorticity and potential vorticity, and scaling and approximations. It discusses baroclinic and barotropic instabilities, wave-mean flow interactions and turbulence, and the general circulation of the atmosphere and ocean. Student problems and exercises are included at the end of each chapter. Atmospheric and Oceanic Fluid Dynamics: Fundamentals and Large-Scale Circulation will be an invaluable graduate textbook on advanced courses in GFD, meteorology, atmospheric science and oceanography, and an excellent review volume for researchers. Additional resources are available at www.cambridge.org/9780521849692.
Download or read book Meteorology of Tropical West Africa written by Douglas J. Parker and published by John Wiley & Sons. This book was released on 2017-02-13 with total page 493 pages. Available in PDF, EPUB and Kindle. Book excerpt: Meteorology of tropical West Africa: the Forecasters’ Handbook presents the science and practice of weather forecasting for an important region of the tropics. Connecting basic theory with forecasting practice, the book provides a unique training volume for operational weather forecasters, and is also suitable for students of tropical meteorology. The West African region contains a number of archetypal climatic zones, meaning that the science of its weather and climate applies to many other tropical regions. West Africa also exhibits some of the world’s most remarkable weather systems, making it an inspiring region for students to investigate. The weather of West Africa affects human livelihoods on a daily basis, and can contribute to hardship, poverty and mortality. Therefore, the ability to understand and predict the weather has the potential to deliver significant benefits to both society and economies. The book includes comprehensive background material alongside documentation of weather forecasting methods. Many examples taken from observations of West African weather systems are included and online case-studies are referenced widely.
Download or read book The Global Monsoon System written by Chih-Pei Chang and published by World Scientific. This book was released on 2011 with total page 609 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a current review of the science of monsoon research and forecasting. The contents are based on the invited reviews presented at the World Meteorological Organization's Fourth International Workshop on Monsoons in late 2008, with subsequent manuscripts revised from 2009 to early 2010. The book builds on the concept that the monsoons in various parts of the globe can be viewed as components of an integrated global monsoon system, while emphasizing that significant region-specific characteristics are present in individual monsoon regions. The topics covered include all major monsoon regions and time scales (mesoscale, synoptic, intraseasonal, interannual, decadal, and climate change). It is intended to provide an updated comprehensive review of the current status of knowledge, modeling capability, and future directions in the research of monsoon systems around the world.
Download or read book Saharan Dust and the African Easterly Jet African Easterly Wave System written by Emily C. Bercos-Hickey and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The direct radiative effects of Saharan mineral dust (SMD) aerosols on the structure, location, and energetics of the African easterly jet-African easterly wave (AEJ-AEW) system are examined for July-September 2006. Experiments are conducted with and without SMD using the Weather Research and Forecasting (WRF) model coupled to an interactive dust model. The SMD causes the AEJ to shift northward, upward, and eastward, and enhances its zonal asymmetry. The SMD also causes the north and south AEW tracks to shift northward and increases the zonal asymmetry of the AEWs; the consequence of this asymmetry is a contraction in the zonal scale and a slowing of the westward migration of the AEWs. The SMD also strengthens the energy conversions within the AEJ-AEW system. With SMD, the zonally and temporally averaged eddy kinetic energy, baroclinic energy conversion, and barotropic energy conversion increase by as much as 35%, 50% and 70%, respectively. The SMD-modified generation of eddy available potential energy is more than 70% greater than without SMD, and occurs on the north side of the AEJ, where the meridional SMD gradient is maximized.
Download or read book Meteorology of Tropical West Africa written by Douglas J. Parker and published by John Wiley & Sons. This book was released on 2017-04-24 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt: Meteorology of tropical West Africa: the Forecasters’ Handbook presents the science and practice of weather forecasting for an important region of the tropics. Connecting basic theory with forecasting practice, the book provides a unique training volume for operational weather forecasters, and is also suitable for students of tropical meteorology. The West African region contains a number of archetypal climatic zones, meaning that the science of its weather and climate applies to many other tropical regions. West Africa also exhibits some of the world’s most remarkable weather systems, making it an inspiring region for students to investigate. The weather of West Africa affects human livelihoods on a daily basis, and can contribute to hardship, poverty and mortality. Therefore, the ability to understand and predict the weather has the potential to deliver significant benefits to both society and economies. The book includes comprehensive background material alongside documentation of weather forecasting methods. Many examples taken from observations of West African weather systems are included and online case-studies are referenced widely.
Download or read book Effects of Saharan Mineral Dust Aerosols on the Dynamics of an Idealized African Easterly Jet African Easterly Wave System Over North Africa written by Dustin Francis Phillip Grogan and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The central objective of this work is to examine the direct radiative effects of Saharan mineral dust aerosols on the dynamics of African easterly waves (AEWs) and the African easterly jet (AEJ). Achieving this objective is built around two tasks that use the Weather Research and Forecasting (WRF) model coupled to an online dust model (WRF-dust model). The first task (Chapter 2) examines the linear dynamics of AEWs; the second task (Chapter 3) examines the nonlinear evolution of AEWs and their interactions with the AEJ. In Chapter 2, the direct radiative effects of dust on the linear dynamics of AEWs are examined analytically and numerically. The analytical analysis combines the thermodynamic equation with a dust continuity equation to form an expression for the generation of eddy available potential energy (APE) by the dust field. The generation of eddy APE is a function of the transmissivity and spatial gradients of the dust, which are modulated by the Doppler-shifted frequency. The expression predicts that for a fixed dust distribution, the wave response will be largest in regions where the dust gradients are maximized and the Doppler-shifted frequency vanishes. The numerical analysis calculates the linear dynamics of AEWs using zonally averaged basic states for wind, temperature and dust consistent with summertime conditions over North Africa. For the fastest growing AEW, the dust increases the growth rate from ~15% to 90% for aerosol optical depths ranging from [tau]=1.0 to [tau]=2.5. A local energetics analysis shows that for [tau]=1.0, the dust increases the maximum barotropic and baroclinic energy conversions by ~50% and ~100%, respectively. The maxima in the generation of APE and conversions of energy are co-located and occur where the meridional dust gradient is maximized near the critical layer, i.e., where the Doppler-shifted frequency is small, in agreement with the prediction from the analytical analysis. In Chapter 3, the direct radiative effects of dust on the evolution of AEJ-AEW system are examined using the WRF-dust model. The model is initialized with zonal-mean distributions of wind, temperature and dust used in linear study (Chapter 2). The dust modifies the lifecycle of the AEWs in the following way: the domain-averaged eddy kinetic energy (EKE) is enhanced during the linear and nonlinear growth phases, reaching a larger peak amplitude that subsequently decays more rapidly, eventually equilibrating at lower amplitude. The increase in EKE during the growth phases is due to local increases in barotropic energy conversions in the dust plume north of the AEJ. The dust-modified, rapidly decaying phase is primarily associated with enhanced barotropic decay that occurs near the top of the plume north of the AEJ. The timing of peak EKE depends on the initial dust concentration. Throughout the evolution of the AEJ-AEW system, the dust increases the maximum zonal-mean wind speeds. The increase is due to the dust-modified mean meridional circulation during the AEW growth phase and the dust-modified wave fluxes during the AEW decay phase. During AEW growth, the dust-modified maximum wind speeds are also displaced farther southward and upward, which is due to the enhanced wave fluxes decelerating the flow more efficiently north of the AEJ. These changes to the AEJ structure affect the critical surface, which expands vertically and meridionally as the AEW grows to finite amplitude. The dust-modified effects on the evolution of the AEJ-AEW system are discussed in light of tropical cyclogenesis. By better understanding the direct radiative effects of dust on the AEJ-AEW system, we can expect improvements in the modeling, forecasting and understanding of the connection between AEWs and the meteorology over North Africa and the Eastern Atlantic Ocean.
Download or read book Dryland Climatology written by Sharon E. Nicholson and published by Cambridge University Press. This book was released on 2011-10-27 with total page 529 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive overview of dryland climates and their relationship to the physical environment, vegetation, hydrology, and inhabitants. Packed with photographs and an extensive review of the primary literature, this is a unique interdisciplinary resource for researchers, environmental professionals and advanced students in fields from climatology to geomorphology.
Download or read book Studies Of Cloud Convection And Precipitation Processes Using Satellite Observations written by William B Rossow and published by World Scientific. This book was released on 2022-10-26 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: Clouds, convection and precipitation processes are central components of Earth's weather and climate. They are produced by atmospheric motions across a very wide range of space-time scales from local weather to long-term global climate variation. They feedback on these motions by perturbing the heating/cooling that drive the atmospheric circulation. These processes also perturb the oceanic circulation and land surface properties that affect the atmospheric circulation.Because of the coupling of the atmosphere-ocean-land system across all scales by cloud, convection and precipitation processes, studying their behaviors requires measurements in space-time variations across all these scales simultaneously. Satellite constellations with global coverage and high time resolution offer the ideal platforms for such observations. This book summarizes some of the latest research using combinations of various satellite observations to study these processes and to evaluate their representations in global weather and climate models.Included with this publication are downloadable electronic slides and accompanying notes of each lecture for students, teachers, and public speakers around the world to be better able to understand cloud, convection and precipitation processes.
Download or read book Next Generation Earth System Prediction written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2016-08-22 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the nation's economic activities, security concerns, and stewardship of natural resources become increasingly complex and globally interrelated, they become ever more sensitive to adverse impacts from weather, climate, and other natural phenomena. For several decades, forecasts with lead times of a few days for weather and other environmental phenomena have yielded valuable information to improve decision-making across all sectors of society. Developing the capability to forecast environmental conditions and disruptive events several weeks and months in advance could dramatically increase the value and benefit of environmental predictions, saving lives, protecting property, increasing economic vitality, protecting the environment, and informing policy choices. Over the past decade, the ability to forecast weather and climate conditions on subseasonal to seasonal (S2S) timescales, i.e., two to fifty-two weeks in advance, has improved substantially. Although significant progress has been made, much work remains to make S2S predictions skillful enough, as well as optimally tailored and communicated, to enable widespread use. Next Generation Earth System Predictions presents a ten-year U.S. research agenda that increases the nation's S2S research and modeling capability, advances S2S forecasting, and aids in decision making at medium and extended lead times.
Download or read book Response of Regional Climate to Global Forcing written by Christopher Bryan Skinner and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There is now unequivocal evidence that the Earth's climate is changing as a result of human activities. These changes pose a number of potential risks for human and natural systems. Within the Sahel, a semi-arid region of northern Africa that is home to over 50 million people, climate-related stresses on human systems are exacerbated by a limited capacity for climate adaptation and persistent uncertainty in projections of future climate. In this dissertation I utilize a suite of numerical modeling techniques in conjunction with observational data to study the multi-scale interactions that shape rainfall and atmospheric circulation in northern West Africa. This dissertation consists of three chapters. In the first chapter, I use an ensemble of general circulation model experiments to examine the relative roles of different global drivers in shaping projected changes in West African climate. Specifically, I assess the response of precipitation and atmospheric circulation in West Africa to the individual influences of direct atmospheric radiative forcing from projected increases in greenhouse gas concentrations and greenhouse gas-induced sea surface temperature forcing. In the second chapter, I evaluate the simulation of synoptic-scale weather disturbances, known as African easterly waves, in the latest generation of global climate models. African easterly waves serve as an important source of Sahel rainfall and play a critical role in Saharan dust transport and the initiation of the most intense Atlantic basin hurricanes. In this work I identify key reasons for biases in the simulation of African easterly waves, and offer several new insights for improved climate modeling efforts in West Africa. In the third chapter, I explore the response of atmospheric circulation in West Africa to projected increases in greenhouse gas concentrations. Models exhibit a robust increase in monsoon strength and African easterly wave activity in response to the pattern of future warming in West Africa. These results suggest the possibility of a number of future climate-related impacts on human and natural systems in West Africa and the greater Atlantic basin.
Download or read book Climate Variability written by Aondover Tarhule and published by BoD – Books on Demand. This book was released on 2013-08-28 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: As societies transition to evidence-based adaptation and management there is increasing recognition of the need for understanding climate change and variability dynamics and impacts at regional levels and for various activities. This book is a contribution toward that goal. Readers interested in climate change management will find detailed discussions of climatic variability dynamics in selected regions as well as new innovative ways of monitoring climate change, assessing climate risks, and predicting impacts. Those interested in refreshing the fundamentals of climate change and climate variability will find a very accessible review of the status of knowledge on the subject, including a balanced interrogation of available evidence. In an attempt to keep the book accessible, every effort was made to minimize technical jargon without compromising scientific accuracy. The result should be useful to researchers, practitioners, and policy makers.
Download or read book Tropical Meteorology written by T.N. Krishnamurti and published by Springer Science & Business Media. This book was released on 2013-07-14 with total page 427 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is designed as an introductory course in Tropical Meteorology for the graduate or advanced level undergraduate student. The material within can be covered in a one-semester course program. The text starts from the global scale-view of the Tropics, addressing the zonally symmetric and asymmetric features of the tropical circulation. It then goes on to progressively smaller spatial and time scales – from the El Niño Southern Oscillation and the Asian Monsoon, down to tropical waves, hurricanes, sea breezes, and tropical squall lines. The emphasis in most chapters is on the observational aspects of the phenomenon in question, the theories regarding its nature and maintenance, and the approaches to its numerical modeling. The concept of scale interactions is also presented as a way of gaining insight into the generation and redistribution of energy for the maintenance of oscillations of a variety of spatial and temporal scales.
Download or read book The Interaction of Ocean Waves and Wind written by Peter Janssen and published by Cambridge University Press. This book was released on 2004-10-28 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book was published in 2004. The Interaction of Ocean Waves and Wind describes in detail the two-way interaction between wind and ocean waves and shows how ocean waves affect weather forecasting on timescales of 5 to 90 days. Winds generate ocean waves, but at the same time airflow is modified due to the loss of energy and momentum to the waves; thus, momentum loss from the atmosphere to the ocean depends on the state of the waves. This volume discusses ocean wave evolution according to the energy balance equation. An extensive overview of nonlinear transfer is given, and as a by-product the role of four-wave interactions in the generation of extreme events, such as freak waves, is discussed. Effects on ocean circulation are described. Coupled ocean-wave, atmosphere modelling gives improved weather and wave forecasts. This volume will interest ocean wave modellers, physicists and applied mathematicians, and engineers interested in shipping and coastal protection.
