Download or read book The Long term Change of El Ni o Southern Oscillation in an Ensemble Reanalysis and Climate Coupled Models written by Chunxue Yang and published by . This book was released on 2013 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Long-term changes of El Niño/Southern Oscillation (ENSO) are studied with the ensemble run of Simple Ocean Data Assimilation (SODA 2.2.6) and the Coupled Model Intercomparison Project Phase 5 (CMIP5). An eight member ocean reanalyses (SODA 2.2.6) from 1871 to 2008 is produced by using forcing from eight ensemble members of an atmospheric reanalysis. The ensemble reanalysis shows that El Niño has prominent decadal variability. Weak El Niños occur throughout the entire record whereas the occurrence of strong El Niños varies, with strong El Niño at the beginning and end of the record. The strength of La Niña is weaker than for El Niño, and has less variability. Although for any given El Niño year all ensemble members show the occurrence of El Niño, in some ensemble members the El Niño is strong while in others it is weak. When the timing of the onset of Westerly Wind Bursts (WWBs) occurs earlier in the year and the strength of WWBs is stronger, strong El Niño occurs. To study the importance of the background state in the tropical Pacific Ocean on ENSO, long-term trends of tropical Pacific SST, wind stress, subsurface temperature and the sub-tropical cells (STCs) are analyzed. The reanalysis shows that there is a slight cooling trend of SST in the central tropical Pacific due to an enhanced tropical Pacific circulation. Subsurface temperature also has a cooling trend. The STCs, which consist of equatorial upwelling, Ekman transport, extra-tropical subduction and pycnocline transport from the sub-tropical to the tropical region, strengthen from 1900 to 2008. When the STCs are accelerated, equatorial upwelling increases bringing cold water from the subsurface that cools the surface. ENSO variability is also analyzed in the CMIP5 historical experiments. Results show that most of the models have a realistic representation of the strength of ENSO; however, the location of warming generally extends too far to the west. Overall, properties of ENSO do not show a significant change in most of the CMIP5 models. One distinguishing difference between the CMIP5 models and SODA 2.2.6 is that ENSO in SODA 2.2.6 has prominent asymmetry between El Niño and La Niña, whereas ENSO in the CMIP5 models tends to have fairly symmetric El Niño and La Niña. In contrast with the reanalysis most of the CMIP5 models have warming trends at the surface and the transport of the STCs has a decreasing trend. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148283

Download or read book El Ni o Southern Oscillation in a Changing Climate written by Michael J. McPhaden and published by John Wiley & Sons. This book was released on 2020-11-24 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive and up-to-date information on Earth’s most dominant year-to-year climate variation The El Niño Southern Oscillation (ENSO) in the Pacific Ocean has major worldwide social and economic consequences through its global scale effects on atmospheric and oceanic circulation, marine and terrestrial ecosystems, and other natural systems. Ongoing climate change is projected to significantly alter ENSO's dynamics and impacts. El Niño Southern Oscillation in a Changing Climate presents the latest theories, models, and observations, and explores the challenges of forecasting ENSO as the climate continues to change. Volume highlights include: Historical background on ENSO and its societal consequences Review of key El Niño (ENSO warm phase) and La Niña (ENSO cold phase) characteristics Mathematical description of the underlying physical processes that generate ENSO variations Conceptual framework for understanding ENSO changes on decadal and longer time scales, including the response to greenhouse gas forcing ENSO impacts on extreme ocean, weather, and climate events, including tropical cyclones, and how ENSO affects fisheries and the global carbon cycle Advances in modeling, paleo-reconstructions, and operational climate forecasting Future projections of ENSO and its impacts Factors influencing ENSO events, such as inter-basin climate interactions and volcanic eruptions The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Find out more about this book from this Q&A with the editors.

Download or read book The El Ni o Southern Oscillation Phenomenon written by Edward S. Sarachik and published by Cambridge University Press. This book was released on 2010-02-18 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many climatic extremes around the globe, such as severe droughts and floods, can be attributed to the periodic warming of the equatorial Pacific sea surface, termed the El Niño or Southern Oscillation (ENSO). Advances in our understanding of ENSO, in which Edward S. Sarachik and Mark A. Cane have been key participants, have led to marked improvements in our ability to predict its development months or seasons, allowing adaptation to global impacts. This book introduces basic concepts and builds to more detailed theoretical treatments. Chapters on the structure and dynamics of the tropical ocean and atmosphere place ENSO in a broader observational and theoretical context. Chapters on ENSO prediction, past and future, and impacts, introduce broader implications of the phenomenon. This book provides an introduction to all aspects of this most important mode of global climate variability, for research workers and students of all levels in climate science, oceanography and related fields.

Download or read book Learning to Predict Climate Variations Associated with El Nino and the Southern Oscillation written by National Research Council and published by National Academies Press. This book was released on 1997-01-12 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The TOGA (Tropical Ocean and Global Atmosphere) Program was designed to study short-term climate variations. A 10-year international program, TOGA made El Nino a household word. This book chronicles the cooperative efforts of oceanographers and meteorologists, several U.S. government agencies, many other nations, and international scientific organizations to study El Nino and the Southern Oscillation (ENSO). It describes the progression from being unable to detect the development of large climate variations to being able to make and use rudimentary climate predictions, especially for some tropical countries. It examines the development of the TOGA Program, evaluates its accomplishments, describes U.S. participation in the program, and makes general recommendations for developing better understanding and predictions of climate variations on seasonal to interannual time scales.

Download or read book Climate Extremes written by S.-Y. Simon Wang and published by John Wiley & Sons. This book was released on 2017-06-15 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although we are seeing more weather and climate extremes, individual extreme events are very diverse and generalization of trends is difficult. For example, mid-latitude and subtropical climate extremes such as heat waves, hurricanes and droughts have increased, and could have been caused by processes including arctic amplification, jet stream meandering, and tropical expansion. This volume documents various climate extreme events and associated changes that have been analyzed through diagnostics, modeling, and statistical approaches. The identification of patterns and mechanisms can aid the prediction of future extreme events. Volume highlights include: Compilation of processes and mechanisms unique to individual weather and climate extreme events Discussion of climate model performance in terms of simulating high-impact weather and climate extremes Summary of various existing theories, including controversial ones, on how climate extremes will continue to become stronger and more frequent Climate Extremes: Patterns and Mechanisms is a valuable resource for scientists and graduate students in the fields of geophysics, climate physics, natural hazards, and environmental science. Read an interview with the editors to find out more: https://eos.org/editors-vox/how-does-changing-climate-bring-more-extreme-events

Download or read book Reconstructing Past Changes in El Ni o Southern Oscillation Variability Using Geochemical Proxies from Corals written by Allison E. Lawman and published by . This book was released on 2020 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: The El Niño-Southern Oscillation (ENSO) is the leading mode of interannual (>1-9 year) climate variability and has far-reaching impacts on global temperature and rainfall patterns. That said, the instrumental record of ENSO does not have the temporal coverage necessary to characterize the full range of natural variability. Uncertainties about how ENSO variability may change in the future with anthropogenic warming motivates the study of past climate conditions when the Earth experienced different climate conditions compared to the warm, rapidly changing climate of today. Climate scientists use two primary tools to study past climate. First, general circulation models use mathematical equations based on physical principles to simulate different aspects of the climate system, including the ocean, atmosphere, land, and ice sheets. Second, various geological archives like corals, cave stalagmites and lake and ocean sediment also provide clues about how the climate varied in the past. The paleoclimate proxy records generated from geological archives thus provide independent validation of paleoclimate model simulations. Geochemical proxy records from corals are particularly well-suited for investigating past (paleo) ENSO variability as corals can provide decades to hundreds of years of climate information from the tropics at sub-annual resolution. This dissertation seeks to quantify changes in paleo-ENSO variability using geochemical proxies from corals. I first generate replicated coral records from Vanuatu in the southwest Pacific to investigate the range of ENSO variability during the 20th century and ~900 years during a time interval called the Medieval Climate Anomaly. The paleo-temperature records are based on the ratio of strontium to calcium (Sr/Ca) of massive Porites corals from Vanuatu. Next, I develop various computational algorithms to investigate how different uncertainties inherent to the coral archive impact the ability of a coral to capture changes in ENSO variability. The algorithms incorporate the impact of variable growth rates, analytical and calibration errors, and age model assumptions, and are collectively referred to a coral proxy system model (PSM). The utility of the coral PSM is demonstrated using unforced climate model output for the last millennium. I then use the PSM and apply the analytical techniques developed in the first two projects to investigate simulated and coral proxy-inferred changes in paleo-ENSO variability during the Holocene (11.65 thousand years ago to the present). The resulting model-data comparison provides a new perspective on long-term changes in ENSO variability

Download or read book A New Approach to El Ni o Southern Oscillation Origin and Forecasting written by Desislava Bozhidarova Petrova and published by . This book was released on 2017 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: "El Niño Southern Oscillation arises in the tropical Pacific due to coupled atmosphere-ocean interactions. The nature of the dynamical system of the atmosphere is chaotic and its predictability is sensitive to initial conditions, which constraints our ability to foresee the evolution of ENSO for very long time in advance. This dissertation is dedicated to extending the state-of-the-art prediction of the phenomenon. It focuses on the identification of precursory signals in the ocean and atmosphere that improve the understanding and long-lead forecasts of ENSO. A new statistical modelling technique based on dynamic components and state-space methods is developed. Very early premonitory signals that are a result of an in-depth analysis of the processes accompanying the origin and evolution of El Niño, especially in the subsurface ocean, which is less impacted by initial conditions, are established. These tracers are defined in the far western and central tropical Pacific and are shown to anticipate El Niño two and a half years before its peak. Initial intensification of the easterly winds at this time is associated with convergence of mass, downwelling and warming of the subsurface ocean layers in the far west. Thus the South Equatorial Current and the Equatorial Undercurrent are strengthened, which leads to the propagation of warm subsurface anomalies eastward. These anomalous patterns later lead to changes in the circulation and warming of the surface of the ocean in the central tropical Pacific, which leads to the suppression of the easterly winds. The area of tropical convection shifts to the east, which weakens the Walker circulation and triggers the Bjerknes feedback. This allows the further propagation of the subsurface warm anomalies, which reach the eastern Pacific and are upwelled to the surface, which marks the onset of an El Niño . Warm anomalies in the subsurface equatorial ocean have been previously used as precursors in statistical ENSO models via the integration of the upper ocean heat content or the incorporation of anomalies of the 20°C isotherm. In this way the propagation feature of the anomalies is not considered, and no direct connection is made between the first anomalous patterns and the occurrence of a warm event. Hence, the predictive potential of the incipient warming in the western Pacific is not harnessed. Thus, the work presented in the dissertation provides implications for the possibility to improve the long-lead capabilities of other models. The definition of ENSO predictors at specific depths and regions in the ocean and atmosphere requires the reliable surface and subsurface measurements of various climate variables. Regular measurements have only begun with the satellite era in the 1980s, and with the placement of an observation system after the Tropical Ocean Global Atmosphere Program (1985-1994). Forecasts with the model developed here substantially improve after 1994, and the change is distinct for the long-lead forecasts that rely on good-quality subsurface information about the ocean thermal structure. Therefore, the higher temporal and spatial resolution data sets of key variables are now long enough for statistical forecasting models to make better use of. The practical utility of multi-year forecasts is also explored. A well established link exists between ENSO and local climate in the coastal areas of Ecuador. Following El Niño is a warmer surface temperature and enhanced precipitation. These two variables control the dynamics of mosquito population, and in this way affect the incidence of dengue. An experiment is performed where long-lead forecasts of El Niño are used within a dengue model and the prospects for developing an early warning system is investigated." -- TDX.

Download or read book The El Ni o Phenomenon written by United Nations Environment Programme and published by UN. This book was released on 1992 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: An examination of the effects of, and research into, the El Nino phenomenon. Originating in the Pacific region, El Nino effects a reversal in the direction of winds and ocean currents, and changes in ocean temperature between Indonesia and the Pacific coas

Download or read book Earth s Climate written by Chunzai Wang and published by American Geophysical Union. This book was released on 2004-01-09 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 147. It is more than 30 years since the publication of Jacob Bjerknes' groundbreaking ideas made clear the importance of ocean-atmosphere interaction in the tropics. It is now more than 20 years since the arrival of a massive El Niño in the fall of 1982 set off a cascade of observational and theoretical studies. During the following decades, the climate research community has made exceptional progress in refining our capacity to observe earth's climate and theorize about it, including new satellite-based and in situ monitoring systems and coupled ocean-atmosphere predictive numerical models. Of equal importance. is the expanding scope ofresearch, which now reaches far beyond the Pacific El Niño and includes climate phenomena in other ocean basins. In order to cover the now global context of ocean-atmosphere interaction we have organized this monograph around five principal themes, each introduced by one or more broad overview papers. Theme I covers interaction and climate variability in the Pacific sector, with extensive discussion of El Niño-Southern Oscillation, and with the possible causes and consequences of variability on both shorter and longer timescales. Theme II is devoted to interaction in the Atlantic sector. This basin exhibits complex behavior, reflecting its geographic location between two major zones of convection as well as neighboring the tropical Pacific. Theme III reviews the recent, exciting progress in our understanding of climate variability in the Indian sector. Theme IV addresses the interaction between the tropics and the extratropics, which are linked through the presence of shallow meridional overturning cells in the ocean. Finally, Theme V discusses overarching issues of cross-basin interaction.

Download or read book Assessment of Intraseasonal to Interannual Climate Prediction and Predictability written by National Research Council and published by National Academies Press. This book was released on 2010-10-08 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: More accurate forecasts of climate conditions over time periods of weeks to a few years could help people plan agricultural activities, mitigate drought, and manage energy resources, amongst other activities; however, current forecast systems have limited ability on these time- scales. Models for such climate forecasts must take into account complex interactions among the ocean, atmosphere, and land surface. Such processes can be difficult to represent realistically. To improve the quality of forecasts, this book makes recommendations about the development of the tools used in forecasting and about specific research goals for improving understanding of sources of predictability. To improve the accessibility of these forecasts to decision-makers and researchers, this book also suggests best practices to improve how forecasts are made and disseminated.

Download or read book On the Impacts of the Indian Summer Monsoon on ENSO in a Coupled GCM written by Renguang Wu and published by . This book was released on 2002 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The El Ni o Southern Oscillation Phenomenon written by Edward S. Sarachik and published by Cambridge University Press. This book was released on 2010-02-18 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many climatic extremes around the globe, such as severe droughts and floods, can be attributed to the periodic warming of the equatorial Pacific sea surface, termed the El Niño or Southern Oscillation (ENSO). Advances in our understanding of ENSO, in which Edward Sarachik and Mark Cane have been key participants, have led to marked improvements in our ability to predict its development months or seasons, allowing adaptation to global impacts. The book introduces basic concepts and builds to more detailed theoretical treatments. Chapters on the structure and dynamics of the tropical ocean and atmosphere place ENSO in a broader observational and theoretical context. Chapters on ENSO prediction, past and future, and impacts introduce broader implications of the phenomenon. This book provides an introduction to all aspects of this most important mode of global climate variability, for research workers and students of all levels in climate science, oceanography and related fields.

Download or read book Climate Variability and the Global Harvest written by Cynthia Rosenzweig and published by Oxford University Press. This book was released on 2008-01-07 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Earth's climate is constantly changing. Some of the changes are progressive, while others fluctuate at various time scales. The El Niño-la Niña cycle is one such fluctuation that recurs every few years and has far-reaching impacts. It generally appears at least once per decade, but this may vary with our changing climate. The exact frequency, sequence, duration and intensity of El Niño's manifestations, as well as its effects and geographic distributions, are highly variable. The El Niño-la Niña cycle is particularly challenging to study due to its many interlinked phenomena that occur in various locations around the globe. These worldwide teleconnections are precisely what makes studying El Niño-la Niña so important. Cynthia Rosenzweig and Daniel Hillel describe the current efforts to develop and apply a global-to-regional approach to climate-risk management. They explain how atmospheric and social scientists are cooperating with agricultural practitioners in various regions around the world to determine how farmers may benefit most from new climate predictions. Specifically, the emerging ability to predict the El Niño-Southern Oscillation (ENSO) cycle offers the potential to transform agricultural planning worldwide. Biophysical scientists are only now beginning to recognize the large-scale, globally distributed impacts of ENSO on the probabilities of seasonal precipitation and temperature regimes. Meanwhile, social scientists have been researching how to disseminate forecasts more effectively within rural communities. Consequently, as the quality of climatic predictions have improved, the dissemination and presentation of forecasts have become more effective as well. This book explores the growing understanding of the interconnectedness of climate predictions and productive agriculture for sustainable development, as well as methods and models used to study this relationship.

Download or read book Climate Dynamics written by De-Zheng Sun and published by John Wiley & Sons. This book was released on 2013-05-02 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 189. Climate Dynamics: Why Does Climate Vary? presents the major climate phenomena within the climate system to underscore the potency of dynamics in giving rise to climate change and variability. These phenomena include deep convection over the Indo-Pacific warm pool and its planetary-scale organization: the Madden-Julian Oscillation, the monsoons, the El Niño-Southern Oscillation, the Pacific Decadal Oscillation, and the low-frequency variability of extratropical circulations. The volume also has a chapter focusing on the discussion of the causes of the recent melting of Arctic sea ice and a chapter devoted to the discussion of the causes of recent changes in the frequency and intensity of tropical cyclones. On each topic, the basic material of climate dynamics is covered to aid the understanding of the forefront research, making the volume accessible to a broad spectrum of readers. The volume highlights include Diabatic and nonlinear aspects of the El Niño-Southern Oscillation Causes of sea ice melting in the Arctic Impact of global warming on tropical cyclone activity Origins of the Pacific Decadal Oscillation Causes of climate variability of Asian monsoons The volume will be of particular interest to graduate students and young researchers in atmospheric and oceanic sciences and related disciplines such as geology and geography. The book will also be a good read for those who have a more general interest in the Earth's climate and why it varies.

Download or read book Analyzing El Ni o Southern Oscillation Sensitivity in a Large Ensemble of Ocean Reanalyses written by Kelley A Bradley and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A 56-member ensemble of ocean reanalyses is used to explore strong El Niño events in two 5-year periods, 1916 to 1920 and 1996 to 2000, that have markedly different quantities of observations. To generate the 56 forcing fields, we use a 56 member atmospheric reanalysis (20CRv2 system). Prescribed as boundary conditions were 8 different sea surface temperature (SST) estimates from an ocean reanalysis system, SODA with sparse input (SODA.si1), resulting in 8 sets of 7 ensemble members each. The 56 atmospheric reanalyses were used to force an ocean reanalysis for the same two time periods. The ocean reanalyses, SODA_XP, are used to explore ENSO sensitivity in the tropical Pacific Ocean. Results from the two periods show two sources of uncertainty in the reanalyses. One source is the inherent atmospheric noise that partially causes the representation of the same ENSO event to vary widely in strength, duration, and location among the 56 ensemble members. For example, warming during the 1918/1919 event in some members is far in the eastern equatorial Pacific Ocean while in other members the major warming is in the central Pacific. The other source of uncertainty comes from prescribing SST to the atmosphere, and is primarily responsible for differences seen among ensemble members. During the well-observed 1996-2000 period, the ensemble variance is considerably smaller than that of the 1916-1920 period, thus a markedly reduced level of uncertainty. Similarities among the results of each atmospheric reanalysis set generated with the same SODAsi.1 SST suggest that the state estimates are strongly dependent upon the SST boundary condition. The results add to what is previously known about ENSO in order to improve ENSO predictability, as well as highlight the importance of loosely coupling ocean and atmosphere reanalyses to adequately represent the range of possible climate states in periods of few observations. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155238

Download or read book An Introduction to the Dynamics of El Nino and the Southern Oscillation written by Allan J. Clarke and published by Elsevier. This book was released on 2008-01-28 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many scientists either working on the El Niño/Southern Oscillation (ENSO) problem or its many applications have not been trained in both the equatorial ocean and atmospheric dynamics necessary to understand it. This book seeks to overcome this difficulty by providing a step by step introduction to ENSO, helping the upper level graduate student or research scientist to learn quickly the ENSO basics and be up to date with the latest ENSO research. The text assumes that the reader has a knowledge of the equations of fluid mechanics on a rotating earth and emphasizes the observations and simple physical explanations of them. Following a history of ENSO and a discussion of ENSO observations in Chapters 1 and 2, Chapters 3-5 consider relevant equatorial ocean dynamics, Chapters 6 and 9 relevant atmospheric dynamics, and Chapters 7 and 8 the main paradigms for how the Pacific Ocean and atmosphere couple together to produce ENSO. Chapter 8 also discusses the old mystery of why ENSO tends to be locked in phase with the seasonal cycle. Successful dynamical and statistical approaches to ENSO prediction are discussed in Chapters 10 and 11 while Chapter 12 concludes the book with examples of how ENSO influences marine and bird life. - Quick reference guide and step by step introduction to El Niño/Southern Oscillation dynamics - Keep informed and up to date on El Niño/Southern Oscillation research and how El Niño and the Southern Oscillation can be predicted - Understand how El Niño can affect marine and bird life

Download or read book On the Bimodality of ENSO Cycle Extremes written by Robert M. Wilson and published by . This book was released on 2000 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: On the basis of sea surface temperature in the El Niño 3.4 region (5° N.-5° S., 120°-170° W.) during the interval of 1950-1997, Kevin Trenberth previously has identified some 16 El Niño and 10 La Niña, these 26 events representing the extremes of the quasi-periodic El Niño-Southern Oscillation (ENSO) cycle. Runs testing show that the duration, recurrence period, and sequencing of these extremes vary randomly. Hence, the decade of the 1990's especially for El Niño, is not significantly different from that of previous decadal epochs, at least, on the basis of the frequency of onsets of ENSO extremes. Additionally, the distribution of duration for both El Niño and La Niña looks strikingly bimodal, each consisting of two preferred modes, about 8- and 16-mo long for El Niño and about 9- and 18-mo long for La Niña, as does the distribution of the recurrence period for El Niño, consisting of two preferred modes about 21- and 50-mo long. Scatterplots of the recurrence period versus duration for El Niño are found to be statistically important, displaying preferential associations that link shorter (or longer) duration with shorter (longer) recurrence periods. Because the last onset of El Niño occured in 1997 and the event was of longer than average duration, onset of the next anticipated El Niño is not expected until February 2000 or later.