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Book Decadal Variability of the Pacific Subtropical Cells and Equatorial Sea Surface Temperature

Download or read book Decadal Variability of the Pacific Subtropical Cells and Equatorial Sea Surface Temperature written by Carina Saxton Young and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis investigates possible dynamical pathways through which variability in the extra-tropical Pacific Ocean influences decadal fluctuations of tropical Pacific sea surface temperatures (SST). Specifically, we examine the hypothesis that low-frequency changes in the Pacific‟s meridional subtropical cells (STCs), which transport subsurface water masses equatorward from the extra-tropical into the tropical Pacific upwelling system, modulate decadal variations of the equatorial SST. The relationship between the STCs and equatorial Pacific SST anomalies is explored statistically using the monthly hindcast output from the Ocean General Circulation Model (OGCM) for the Earth Simulator (OFES). We find that decadal variability of the subsurface heat transport of the southern branch of the STC is more closely correlated (R = -0.74) with eastern equatorial SST anomalies on timescales longer than 8 years. The northern branch of the STC is overall not well correlated with equatorial SSTa; however, we find that in the period before the 1976 climate shift, the northern cell is more strongly and significantly correlated with equatorial SSTa (R = -0.89,>99%), while the southern cell is not (R = -0.32). The physical significance of these findings remain unclear and requires isolating mechanisms that could lead to an asymmetry in the role of the northern and southern STC in modulating eastern equatorial SSTa during different states of the Pacific climate. This will be a critical step to attribute physical significance to the statistical changes observed before and after the 1976 climate shift.

Book Interhemispheric Water Exchange in the Atlantic Ocean

Download or read book Interhemispheric Water Exchange in the Atlantic Ocean written by G.J. Goni and published by Elsevier. This book was released on 2003-11-12 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent results from modeling and observational studies demonstrate that the tropical Atlantic is a critical region for processes that maintain the meridional overturning circulation, such as cross-equatorial exchanges, and for sea surface temperature variability that impacts on climate variability of the coupled tropical ocean/atmosphere system. The theme of this book is the inter-hemispheric and inter-gyre exchanges of heat, salt and fresh water, while its goal is to improve the knowledge of the tropical Atlantic dynamics and how it affects the global ocean. A clear understanding of the dynamics of processes that affect the flow of mass and heat between the southern and the northern hemispheres in the upper few hundred meters in the tropical Atlantic and of those associated to the ocean circulation or to surface signals, from decadal, inter-annual to mesoscale periods, becomes necessary to better evaluate their contribution to the interhemispheric mass exchange. These processes are believed to be largely responsible in driving the sea surface temperature, which in turn, is a critical parameter to investigate ocean-atmospheric interactions. Output produced by regional models is also used to complement the observations and to provide additional information on their spatial and temporal variability. The subtropical cells, by bringing water masses subducted in the subtropics to the equator, and zonal currents investigated here contribute to the interhemispheric water exchange. Special attention is also given to the warm and salty anticyclonic rings shed by the North Brazil Current, which are now known to have a much broader impact, not only on interhemispheric water mass transfer, but also on the environment of remote regions. Observations from different sources are blended together, are used to validate model outputs and are also assimilated into models to obtain a more complete and accurate picture of the oceanic circulation and of its time evolution.

Book Frontiers in Decadal Climate Variability

Download or read book Frontiers in Decadal Climate Variability written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2016-07-22 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many factors contribute to variability in Earth's climate on a range of timescales, from seasons to decades. Natural climate variability arises from two different sources: (1) internal variability from interactions among components of the climate system, for example, between the ocean and the atmosphere, and (2) natural external forcings, such as variations in the amount of radiation from the Sun. External forcings on the climate system also arise from some human activities, such as the emission of greenhouse gases (GHGs) and aerosols. The climate that we experience is a combination of all of these factors. Understanding climate variability on the decadal timescale is important to decision-making. Planners and policy makers want information about decadal variability in order to make decisions in a range of sectors, including for infrastructure, water resources, agriculture, and energy. In September 2015, the National Academies of Sciences, Engineering, and Medicine convened a workshop to examine variability in Earth's climate on decadal timescales, defined as 10 to 30 years. During the workshop, ocean and climate scientists reviewed the state of the science of decadal climate variability and its relationship to rates of human-caused global warming, and they explored opportunities for improvement in modeling and observations and assessing knowledge gaps. Frontiers in Decadal Climate Variability summarizes the presentations and discussions from the workshop.

Book A Note on the Annual Cycle of Sea Surface Temperature at the Equator

Download or read book A Note on the Annual Cycle of Sea Surface Temperature at the Equator written by Edwin K. Schneider and published by . This book was released on 1996 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book On the Relationship Between the Interannual and Decadal SST Variability in the North Pacific and Tropical Pacific Ocean

Download or read book On the Relationship Between the Interannual and Decadal SST Variability in the North Pacific and Tropical Pacific Ocean written by Sang-Wook Yeh and published by . This book was released on 2002 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Influence of the Sea Surface Temperature Decadal Variability on Tropical Precipitation West African and South American Monsoon

Download or read book Influence of the Sea Surface Temperature Decadal Variability on Tropical Precipitation West African and South American Monsoon written by Julián Villamayor and published by Springer. This book was released on 2019-07-05 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book the Sea Surface Temperature (SST) patterns of decadal-to-multidecadal variability observed and simulated by 17 general circulation models (GCMs) are analyzed. Furthermore, their impact on precipitation in West Africa and South America and the atmospheric mechanisms involved are assessed. Through this analysis, the effect of external forcings on these impacts and the relative contribution of decadal-to-multidecadal variability patterns of SST to precipitation are presented in depth. Finally, a humid period in the West African region of the Sahel during the 19th century, previously little documented, is analyzed using an atmospheric GCM. The monsoons of West Africa and South America have shown changes in the timescales of a few decades. Previous work suggests a relationship with patterns of decadal-to-multidecadal variability of SST, such as global warming and the Atlantic and Pacific variability. However, the dynamics underlying this relationship and its simulation by current GCMs had not been addressed in a consistent manner. This is the main motivation of this book. The results of this book not only represent a great step forward in our understanding of the changes in the precipitation regimes of the studied regions, but they can also be of great help for the improvement of decadal prediction systems and the associated social consequences.

Book Interacting Climates of Ocean Basins

Download or read book Interacting Climates of Ocean Basins written by Carlos R. Mechoso and published by Cambridge University Press. This book was released on 2020-11-26 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive review of interactions between the climates of different ocean basins and their key contributions to global climate variability and change. Providing essential theory and discussing outstanding examples as well as impacts on monsoons, it a useful resource for graduate students and researchers in the atmospheric and ocean sciences.

Book Understanding the Role of Stochastic Atmospheric Forcing in Tropical Pacific Decadal Variability and ENSO Modulation

Download or read book Understanding the Role of Stochastic Atmospheric Forcing in Tropical Pacific Decadal Variability and ENSO Modulation written by Tianyi Sun (Ph. D.) and published by . This book was released on 2019 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interdecadal variability of the tropical Pacific affects global hydroclimate and ecosystem and is suggested to modulate global mean temperature in the past century. It has been long acknowledged that Pacific decadal variability can be generated in the extratropics through integration of stochastic atmospheric forcing by the ocean mixed layer. However, it remains unclear how the extratropical signal propagates into the tropical Pacific and forms a basin-wide anomaly pattern and how the resultant tropical Pacific decadal variability (TPDV) interacts with the El Niño-Southern Oscillation (ENSO), the dominant mode of interannual climate variability. To answer this question, a suite of climate model experiments is conducted with small time-invariant surface heat flux anomalies associated with the leading atmospheric modes in the extratropical South and North Pacific. The results show that subtropical ocean-atmosphere anomalies driven by the surface heat flux forcing propagate into the tropical Pacific mainly through thermodynamic ocean-atmosphere interactions, with ocean dynamics playing an important role in modifying the equatorial sea surface temperature (SST) response. The associated changes in the tropical Pacific mean state not only extend climate anomalies into the other hemisphere through atmospheric teleconnections, but also significantly affect the properties of ENSO. In particular, the ENSO-like TPDV affects the relative frequency of El Niño and La Niña. To investigate the causality and mechanism of this linkage, a separate set of climate model experiments is conducted by imposing surface heat flux anomalies associated with the ENSO-like TPDV in the tropical Pacific. The forced mean state change affects the frequency of El Niño and La Niña events by modulating the SST contrast between the tropical Pacific and the Indian/Atlantic Oceans and associated zonal wind anomalies in the western Pacific. This study presents in detail the atmospheric and oceanic mechanisms by which extratropical atmospheric forcing induces basin-wide coherent patterns of TPDV that can further affect ENSO characteristics, which has not been systematically studied in fully coupled climate models. The results also show that the tropical Pacific is more strongly influenced by the South Pacific through both thermodynamic processes and ocean dynamics. The strong oceanic linkage to the South Pacific allows delayed negative oceanic feedback to effectively affect the equatorial Pacific SST, which may be important for setting up the time scales of TPDV

Book Recent Changes in the Pacific Subtropical Cells Inferred from an Eddy Resolving Ocean General Circulation Model

Download or read book Recent Changes in the Pacific Subtropical Cells Inferred from an Eddy Resolving Ocean General Circulation Model written by and published by . This book was released on 2007 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study the subtropical cells (STC) in the Pacific Ocean are analyzed using an eddy-resolving ocean general circulation model driven by atmospheric forcing for the years 1992-2003. In particular, the authors seek to identify decade changes in the STCs in the model and to compare them with observations in order to understand the consequences of such changes for the equatorial ocean heat and mass budgets. The simulation shows a trend toward increasing pycnocline volume transport at 9 deg N and 9 deg S across the basin from 1992 to 2003. This increase [4.9 plus or minus 1.0 Sv (Sv = 106 cu m/s)] is in qualitative agreement with observations and is attributed primarily to changes in the interior ocean transport, which are partially compensated by opposing western boundary transports. The subtropical meridional volume transport convergence anomalies in the model pycnocline are found to be consistent with anomalous volume transports in both the observed and modeled Equatorial Undercurrent, as well as with the magnitude of simulated anomalous upwelling transport at the base of the mixed layer in the eastern Pacific. As a result of the increased circulation intensity, heat transport divergence through the lateral boundaries of the tropical control volume (defined as the region between 9 degrees N and 9 degrees S, and from the surface to = 25.3 isopycnal) increases, leading to a cooling of the tropical upper ocean despite the fact that net surface heat flux into the control volume has increased in the same time. As such, these results suggest that wind-driven changes in ocean transports associated with the subtropical cells play a central role in regulating tropical Pacific climate variability on decadal time scales.

Book Pacific Decadal Variability and Recent Tropical Expansion

Download or read book Pacific Decadal Variability and Recent Tropical Expansion written by Michael Rollings and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The latitudinal extent of the tropics is of great consequence because it affects agricultural production, water supply, storm frequency, and other factors of socioeconomic importance. The tropics can be defined by climatological metrics such as Hadley cell width, and observations show that the tropics have been expanding poleward since 1979.Tropical width is influenced by both anthropogenic forcing and patterns of large-scale internal climate variability, and the tropics have been expanding faster than coupled models forced with historic levels of anthropogenic forcing. The relative importance of each expansion mechanism has remained unclear since it is difficult to separate the signals of long-term variability, short-term variability, and climate change. Here, we have used statistically-separate patterns of sea surface temperature variability to analyze observations and design general circulation model experiments that isolate the respective roles of internal variability and climate change in recent tropical expansion, allowing us to quantify the influence of Pacific variability on Hadley cell width by timescale. When global warming is defined as independent of natural variability, we find an observed sensitivity of tropical width to global warming that agrees with coupled model experiments. Wealso find a strong correlation between long-term North Pacific variability and Southern Hemisphere Hadley cell extent in observations which cannot be reproduced in prescribed sea surface temperature general circulation model experiments. Conversely, we find a weaker observed relation between El Niño and the Hadley circulation when compared to simulations run with El Niño-like sea surface temperature boundary conditions. The dynamical relation between the Hadley cell and El Niño is generally well understood, but the relative importance of long-term oceanic variability for the general circulationremains unclear because it is difficult to produce the observed trends in simulations with prescribed sea surface temperature"--

Book Dipole like SST Variability in the Tropical Pacific

Download or read book Dipole like SST Variability in the Tropical Pacific written by Sang-Wook Yeh and published by . This book was released on 2005 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book El Ni o Southern Oscillation in a Changing Climate

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.