Interannual to Decadal Predictability in a Coupled Ocean-atmosphere General Circulation Model PDF Download

Author:
Publisher:
ISBN:
Category : Climatic changes
Languages : en
Pages : 32

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Author: David L.T. Anderson
Publisher: Springer Science & Business Media
ISBN: 3662032910
Category : Science
Languages : en
Pages : 498

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Book Description
On decadal time scales, climate change may result not only from man-made causes, but also from natural processes. This book brings together theoretical conceptions of the physical mechanisms of climate change with observational evidence of these changes. The following key topics are included: Observed Climatic Variability, Predictability of the Atmosphere and Oceans from Days to Decades, and Mechanisms for Decadal to Centennial Climate Variability. Further, there are specialised contributions on the role of the oceanic circulation in climate change. The authors are renowned for their pedagogical skills, and the book is primarily designed for beginners in the field, who have a background in physical science. In addition, it is an invaluable source of information for scientists seeking an overview on climate dynamics.

Author: Ben P. Kirtman
Publisher: Elsevier Inc. Chapters
ISBN: 0128058730
Category : Science
Languages : en
Pages : 49

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Book Description
This chapter summarizes the scientific basis for and the current status of seasonal-to-interannual prediction with particular emphasis on the role of the tropical oceans. The first part of the chapter focuses on oceanic sources of predictability in the tropical Pacific, Atlantic, and Indian Oceans. Seasonal-to-interannual predictability issues in the Northern Hemisphere extratropics are also discussed. Mechanisms that limit predictability, particularly for ENSO, are highlighted. The second part of the chapter describes the forecast quality and procedures in practice today. Finally, the concluding remarks identify some outstanding challenges.

Author: National Research Council
Publisher: National Academies Press
ISBN: 0309060982
Category : Science
Languages : en
Pages : 161

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Book Description
Society today may be more vulnerable to global-scale, long-term, climate change than ever before. Even without any human influence, past records show that climate can be expected to continue to undergo considerable change over decades to centuries. Measures for adaption and mitigation will call for policy decisions based on a sound scientific foundation. Better understanding and prediction of climate variations can be achieved most efficiently through a nationally recognized "dec-cen" science plan. This book articulates the scientific issues that must be addressed to advance us efficiently toward that understanding and outlines the data collection and modeling needed.

Author: Mojib Latif
Publisher: Elsevier Inc. Chapters
ISBN: 0128058749
Category : Science
Languages : en
Pages : 60

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Book Description
An inherent feature of the climate is its strong variability on a vast range of timescales, from seasonal to multimillennial and beyond. Decadal variability, which is the topic of this chapter, has large implications for society, as its consequences can be experienced by individuals during their own lifetime. Examples of decadal variability include the Dust Bowl drought of the 1930s in the American and Canadian prairie lands, the Sahel drought of the 1970s and 1980s, the ongoing drought which started in 2000 in the southwestern United States, and the multidecadal variability in Atlantic hurricane activity during the twentieth century. Furthermore, it is the decadal to multidecadal variability that makes the detection of anthropogenic climate change a challenge, since global warming evolves on a similar timescale. The detection problem specifically applies to the regional scale, where natural variability is the strongest. It is a central challenge of climate science to understand and possibly predict such regional-scale climate variability and change over timescales of decades.

Author: Gang Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 171

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Book Description
The Southern Ocean has a critical influence on the global climate, and any long-term variability in the Southern Ocean can have both regional and global impacts significantly. However, sparse observations limit the study of the long-term variation. To test the quality of models simulating the natural sea surface temperature (SST) variability, the SST variability in the global oceans is evaluated in simulations of the Climate Model Intercomparison Project Phase 3 (CMIP3) and CMIP5 models. The result shows that some models demonstrate good skill in simulating the observed spatial structure of the SST variability in the tropical domains and less so in the extra-tropical domains. The CMIP5 ensemble exhibits some improvement over the CMIP3 ensemble, mostly in the tropical domains on SST variability simulation. Further, the spatial structure of the SST modes of the CMIP3 and CMIP5 super ensemble is more realistic than any single model, which is mostly used for the following study. Several SST leading modes in the Southern Ocean are discussed on decadal and even larger time scales using CMIP5 data set based on EOF analysis. We compare the modes against several simple null hypotheses, such as isotropic diffusion (red noise) and a Slab Ocean model, to investigate the sources of decadal variability and the factors affecting the propagation and decay of long-term anomalies. The result reveals that the annular mode with largest amplitudes in the Pacific, the basin-wide monopole mode and South Pacific dipole are the principle patterns with low-frequency variability, which contain the dual effects of internal intrinsic processes as well as external forcing and teleconnections. The annular mode is mostly affected by El Niño Southern Oscillation (ENSO) via teleconnection especially in the South Pacific domain and by local Southern Annular Mode (SAM) over the whole Southern Ocean. The monopole mode and South Pacific dipole mode, while they both demonstrate pronounced multi-decadal and longer time scales variability, are firstly inducted by the Wave-3 patterns in the atmosphere and further developed via ocean dynamics. The causes and characteristics of interannual-decadal SST variability in the Southern Ocean are further investigated with an ocean general circulation model and a simplified band ocean model. Possible factors are examined affecting the generation, propagation and decay of long-term anomalies with a series of sensitivity experiments. We found that the atmospheric forcing not only affects the SST modes on shorter time-scales directly, but also shows its influence on longer time scales via air-sea interaction, amplification and oceanic feedback. The deep mixed layer in the Southern Ocean is an essential element to maintain the long-term SST variability. The ocean dynamics connect the entire ocean and create the homogeneous-like spatial patterns. The ocean advection is the key factor to create SST spectral structure, which concentrates the spectrum on interannnual scale synchronizing with the transport of Antarctic Circumpolar Current (ACC).

Author: Jacques C. J. Nihoul
Publisher: Elsevier Publishing Company
ISBN:
Category : Electronic books
Languages : en
Pages : 800

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Book Description
The exchange of momentum, heat, moisture, gases (such as CO 2 and O 2 ) and salt between the atmosphere and the ocean is a phenomenon of paramount importance for the dynamics of the atmosphere and the ocean. With the pressing need for reliable climate forecast (e.g. to deal with severe food and energy problems) interactive ocean-atmosphere models have become one of the main objectives of geophysical fluid dynamics. This volume provides the first state-of-the-art review of interactive ocean-atmosphere modelling and its application to climates. The papers are by active and eminent scientists from different countries and different disciplines. They provide a up-to-date survey of major recent discoveries and valuable recommendations for future research."

Author: National Research Council
Publisher: National Academies Press
ISBN: 030915183X
Category : Science
Languages : en
Pages : 192

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Book Description
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.

Author: Lindsey Michelle Taylor
Publisher:
ISBN:
Category :
Languages : en
Pages : 46

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Book Description
Improvements to forecasts on interannual to decadal timescales face two major challenges: (1) consistently initializing the coupled system so that variability is not dominated by initial imbalances, and (2) having a large sample of different initial conditions on which to test forecast skill. The second challenge requires consideration of time periods not only outside the recent period of intensive ocean observation, but also before the instrumental era, which increases the importance of the first challenge. Forecasting atmospheric and oceanic conditions prior to the 1850s isolates internally generated sources of variability by removing the majority of anthropogenic forcing, yet the sparse observational record cannot capture low-frequency variability, further emphasizing the importance of both challenges and paleoclimate proxy data. This research addresses these two challenges by using a multivariate linear inverse model (LIM) and recent data assimilation (DA) results that extend the observational record with annually-resolved atmospheric and oceanic variables via a low-cost forecast that taps into ocean memory. The reconstructions provide data throughout the last millennium to initialize, validate, and calibrate the LIM. This work tests the forecast skill of LIMs trained on GCM simulations and on paleo-data assimilated reconstructions. Forecasts are initialized and verified on the reconstructions over 1000-2000 C.E. Both the DA and GCM-analog LIMs are found to have skill on interannual to decadal timescales that surpasses damped persistence for global mean sea surface temperature, as well as widespread significant positive spatial skill for 1-year forecasts of all atmosphere and ocean variables. For cross validation on global mean instrumental data, the LIM trained on paleo-data outperforms a LIM trained on the CCSM4 last millennium simulation beyond 4-year lead forecasts, with the CCSM4-LIM reaching climatological variance before the paleo-informed LIM. The paleo-data LIM requires consistent OHC states that, when provided, increase forecast skill outperformance over the GCM-informed LIMs.

Author: Tim Palmer
Publisher: Cambridge University Press
ISBN: 1139458205
Category : Science
Languages : en
Pages : 693

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Book Description
With contributions by leading experts, including an unpublished paper by Ed Lorenz, this book, first published in 2006, covers many topics in weather and climate predictability. It will interest those in the fields of environmental science and weather and climate forecasting, from graduate students to researchers, by examining theoretical and practical aspects of predictability.