Download or read book The Effect of Horizontal Gyre Circulation on the Stability of Thermohaline Circulation in a Hemispheric and an Interhemispheric Box Model written by Hannah Rachel Longworth and published by . This book was released on 2003 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interhemispheric Thermohaline Circulation in a Coupled Box Model written by Jeffery R. Scott and published by . This book was released on 1998 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) The model is augmented with explicit atmospheric eddy transport parameterizations, allowing examination of the eddy moisture transport (EMT) and eddy heat transport (EHT) feedbacks. As in the hemispheric model, the EMT feedback is always destabilizing, whereas the EHT may stabilize or destabilize. However, in this model whether the EHT stabilizes or destabilizes depends largely on the sign of the ocean salinity feedback and the size of the perturbation. Since oceanic heat transport in the southern hemisphere is weak, the northern hemisphere EMT and EHT feedbacks.
Download or read book 1998 Ocean Sciences Meeting written by and published by . This book was released on 1998 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Inverse Modeling of Seasonal Variations in the North Atlantic Ocean written by Lisan Yu and published by . This book was released on 1998 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optimal Determination of Global Tropospheric OH Concentrations Using Multiple Trace Gases written by Jin Huang and published by . This book was released on 2000 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydroxyl radical (OH) plays a decisive role in tropospheric chemistry. Reactions with OH provide the dominant path of removal for a variety of greenhouse gases and trace species that contribute to the destruction of the ozone layer. Accurate determination of global tropospheric OH concentrations [OH] is therefore a very important issue. Previous research at the global scale has focused on scaling model-calculated OH concentration fields using a single so-called titrating species, either CH3CC13 or 14 CO, and the data usually come from one measurement network. Therefore, the estimation of [OH] relies heavily on the accuracy of the emission estimates and absolute calibration of the observed mixing ratios of that single species. The goal of this thesis is to reduce the dependence of estimating [OH) fields on a single species and thus to improve our knowledge of global OH concentrations and trends. To achieve this goal, we developed a multiple titrating gases scheme which combines all the possible available surface measurements of CH3CC13, CHF2C1 (HCFC-22), CH2FCF3 (HFC-134a), CH3CFC12 (HCFC-141b) and CH3CF 2C1 (HCFC- 142b) from both AGAGE (Advanced Global Atmospheric Gases Experiment) and CMDL/NOAH (Nitrous Oxide And Halocompounds) networks. The optimal estimation of the global OH concentration and its trend is accomplished through a Kalman filtering procedure by minimizing the weighted difference between the predicted mixing ratios from atmospheric chemical-transport models and, for the first time, all the measurements of the various titrating gases simultaneously. A two dimensional land-ocean-resolving (LO) statisticaldynamical model and a 12-box model are used to predict the concentrations of the titrating gases. These two models are computationally efficient, and suitable for repetitive runs and long term integrations. The eddy-diffusive transports in the 12-box model and the 2D-LO model are tuned optimally by using the Kalman filtering and CFC-11 and CFC-12 data before the estimations of OH are carried out. Three different techniques (content method, trend method, and time-varying OH method) are used to perform the Kalman filtering. These three methods optimally fit different features of the measurements and have different sources of errors. Errors in the measurements, industrial emission estimates, and chemical-transport models are included in great detail for the OH estimation problem. The random measurement errors and mismatch errors are included in the noise matrix in the Kalman filter. For other random errors from the emission estimates and chemical-transport models, we use the Q-inclusion method which specifies the random model errors explicitly in the state error matrix Q inside the Kalman filtering. For systematic errors in the calibration, model, and emissions, we use the brute-force method which repeats the entire inverse method many times using different possible values of the measurement sensitivity matrix in the Kalman filtering. Using multiple gases, both CMDL and AGAGE data, two chemical-transport models, and selected content and trend results, our best estimate of the global mean tropospheric OH concentrations is 9.4+2.7/1.7 x 105 radicals cm-3, and our best estimate of the linear OH trend is -0.5±tL1.0% per year over the 1978-1998 time period. Methyl chloroform data give the heaviest weight to the overall estimations. This is because there are more CH3CC13 measurements than for any other titrating gases, and the industrial emission estimates of this gas are the most accurate. The derived OH estimations agree statistically with previous studies taking into account the fact that the negative OH trend derived here relies heavily on the 1993-1998 CH3CCl3 data. For example, a global mean OH concentration of (9.7 ± 0.6) x 105 radicals cm- 3 and an OH trend of 0.0 ± 0.2% per year over the 1978-1993 are reported in Prinn et al. (1995). As far as the major sources of error in the OH estimations are concerned, we find that, using individual gases separately, the uncertainties in absolute calibrations, rate constants, and industrial emissions estimates are important sources of error for all five titrating gases. The measurement errors and the initial a priori guesses in the Kalman filter are also important sources of error for the three newer titrating gases (HCFC-141b, HCFC-142b, and HFC-134a) because of their very low mole fractions as well as the short measurement records for these gases. Combining multiple OH titrating gases together, we find that errors in industrial emissions contribute the most to the uncertainty in the OH estimation problem. We also find that incorporating random model errors (other than mismatch errors) using the Q-inclusion method generates satisfactory agreement for best guess estimates with the approach in which Q = 0 in the Kalman filter. However the Q-inclusion method provides an estimate of the effect of random model error. Newer titrating gases generally yield OH estimates comparable to those from CH3CCl3 but with larger uncertainties. One of the exceptions is using HCFC-142b data with the content method, which yields a physically impossible negative OH concentration because of the underestimates of emissions for this gas. However, the trend method using HCFC-142b data still delivers reasonable OH estimations, because the trend method is not sensitive to systematic errors. The measurements of the newer OH titrating gases can be used effectively with appropriate techniques to ultimately replace the use of CH3CC13 (which is disappearing from the atmosphere), provided estimates of their emissions are improved. This is particularly true for HCFC-142b. In addition to the OH estimations, a time-varying adaptive-Kalman filter is also utilized in this thesis to deduce monthly emissions of HCFC-141b and HCFC-142b. We find that the current industrial estimates of HCFC-142b need to be at least doubled, and the emissions of HCFC-141b need to be increased by 20 to 30% to achieve the best agreement with observations.
Download or read book Measurement and Deduction of Emissions of Short lived Atmospheric Organo chlorine Compounds written by Gary Kleiman and published by . This book was released on 1999 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Global Ocean Circulation Estimated from TOPEX POSEIDON Altimetry and the MIT General Circulation Model written by Detlef Stammer and published by . This book was released on 1997 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Construction of the Adjoint MIT Ocean General Circulation Model and Application to Atlantic Heat Transport Sensitivity written by and published by . This book was released on 1999 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Presenting and Scrutinising a New Box Model for Interhemisphere Thermohaline Circulation written by Jacob Royle and published by . This book was released on 2001 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Terrestrial Sources and Sinks of Atmospheric Methyl Bromide written by Christopher David Jensen and published by . This book was released on 1999 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current estimates of methyl bromide surface fluxes are inconsistent with the observed tropospheric mole fractions (9 to 10 ppt, globally averaged) and the calculated atmospheric lifetime (1.7 ± 0.2 years), with mid-range estimates of sinks exceeding sources by at least 50 Gg y-I. Given the uncertainties in process-specific surface flux estimates, we consider several distributions of terrestrial sources and sinks that satisfy the constraints on atmospheric abundance, Mole fractions corresponding to each distribution are simulated with a three-dimensional chemical transport model based on analyzed observed winds, coupled to a simple model of the ocean mixed layer. All of the resulting scenarios overestimate the observed zonal gradient, with interhemispheric ratios ranging from 1.39 to 1.60. In the absence of unknown sources, model results imply a biomass burning source near the upper limit of the range of present estimates (50 Gg y-1). Sensitivities to surface fluxes are also calculated to determine the extent to which uncertain terms in the methyl bromide budget can be better quantified using long-term measurements. Results show that a global network capable of accurately monitoring the monthly, zonal mean distribution of CH3Br would be able to distinguish between biomass burning fluxes and other known terrestrial sources and sinks. Modeled sensitivities to biomass burning emissions also highlight the importance of including tropical locations in any long-term monitoring network. However, technological sources and soil sinks have similar zonal patterns, and long-term, "background" mole fractions are relatively insensitive to zonal flux distributions. It is only when we examine the high frequency variability of the concentration that the effect of longitudinal gradients in the flux field becomes apparent
Download or read book Abrupt Climate Change written by National Research Council and published by National Academies Press. This book was released on 2002-04-23 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: The climate record for the past 100,000 years clearly indicates that the climate system has undergone periodic-and often extreme-shifts, sometimes in as little as a decade or less. The causes of abrupt climate changes have not been clearly established, but the triggering of events is likely to be the result of multiple natural processes. Abrupt climate changes of the magnitude seen in the past would have far-reaching implications for human society and ecosystems, including major impacts on energy consumption and water supply demands. Could such a change happen again? Are human activities exacerbating the likelihood of abrupt climate change? What are the potential societal consequences of such a change? Abrupt Climate Change: Inevitable Surprises looks at the current scientific evidence and theoretical understanding to describe what is currently known about abrupt climate change, including patterns and magnitudes, mechanisms, and probability of occurrence. It identifies critical knowledge gaps concerning the potential for future abrupt changes, including those aspects of change most important to society and economies, and outlines a research strategy to close those gaps. Based on the best and most current research available, this book surveys the history of climate change and makes a series of specific recommendations for the future.
Download or read book Natural Climate Variability on Decade to Century Time Scales written by National Research Council and published by National Academies Press. This book was released on 1996-08-30 with total page 645 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume reflects the current state of scientific knowledge about natural climate variability on decade-to-century time scales. It covers a wide range of relevant subjects, including the characteristics of the atmosphere and ocean environments as well as the methods used to describe and analyze them, such as proxy data and numerical models. They clearly demonstrate the range, persistence, and magnitude of climate variability as represented by many different indicators. Not only do natural climate variations have important socioeconomic effects, but they must be better understood before possible anthropogenic effects (from greenhouse gas emissions, for instance) can be evaluated. A topical essay introduces each of the disciplines represented, providing the nonscientist with a perspective on the field and linking the papers to the larger issues in climate research. In its conclusions section, the book evaluates progress in the different areas and makes recommendations for the direction and conduct of future climate research. This book, while consisting of technical papers, is also accessible to the interested layperson.
Download or read book Encyclopedia of Ocean Sciences written by John H. Steele and published by Academic Press. This book was released on 2001-09-20 with total page 3399 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Encyclopedia of Ocean Sciences is the most current, authoritative, and comprehensive resource on the science of the oceans. This ambitious work includes contributions from leading scientists around the world on the physical processes that drive the oceans and the chemical, biological, and geological disciplines. The Encyclopedia also covers ancillary topics such as ocean technology, law of the oceans, global programs, marine policy, the use of the oceans for food and energy, and the impact of pollution and climate changes. The many different methods used to study the oceans are covered, from ship-based systems to satellite remote sensing. Users will enjoy easy access to more than 400 articles, each approximately 3000-4000 words in length with further reading lists and extensive cross referencing. Each article provides comprehensive coverage of a particular topic, and is designed for a wide audience of students, academics, researchers, and professionals. The articles are written at a level that allows undergraduate students to understand the material, while providing active researchers with the latest technical information. Also available online on ScienceDirect. For online version information, please visit http://www.info.sciencedirect.com/reference_works Presents 402 original articles covering all the physical, chemical and biological aspects of ocean science Brings together classic scientific theories with the newest discoveries, technologies, and applications Written by the world's leading researchers and developed by a prestigious editorial board Makes information easy to find with an intuitive format, extensive cross references, further reading lists, and complete index Illustrated with more than 1900 figures and full color throughout Developed alongside each other, the Encyclopedia of Ocean Sciences together with the Encyclopedia of Atmospheric Sciences provide readers a with comprehensive resource, and a link between these two fields.
Download or read book Atmosphere Ocean and Climate Dynamics written by John Marshall and published by Academic Press. This book was released on 1978-11-16 with total page 345 pages. Available in PDF, EPUB and Kindle. Book excerpt: For advanced undergraduate and beginning graduate students in atmospheric, oceanic, and climate science, Atmosphere, Ocean and Climate Dynamics is an introductory textbook on the circulations of the atmosphere and ocean and their interaction, with an emphasis on global scales. It will give students a good grasp of what the atmosphere and oceans look like on the large-scale and why they look that way. The role of the oceans in climate and paleoclimate is also discussed. The combination of observations, theory and accompanying illustrative laboratory experiments sets this text apart by making it accessible to students with no prior training in meteorology or oceanography.* Written at a mathematical level that is appealing for undergraduates andbeginning graduate students* Provides a useful educational tool through a combination of observations andlaboratory demonstrations which can be viewed over the web* Contains instructions on how to reproduce the simple but informativelaboratory experiments* Includes copious problems (with sample answers) to help students learn thematerial.
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.
Download or read book The Nordic Seas written by Burton G. Hurdle and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt: " ... as soon as one has traversed the greater part of the wild sea, one comes upon such a huge quantity of ice that nowhere in the whole world has the like been known." "This ice is of a wonderful nature. It lies at times quite still, as one would expect, with openings or large fjords in it; but sometimes its movement is so strong and rapid as to equal that of a ship running before the wind, and it drifts against the wind as often as with it." Kongespeilet - 1250 A.D. ("The Mirror of Kings") Modern societies require increasing amounts influence on the water mass and on the resulting of scientific information about the environment total environment of the region; therefore, cer tain of its characteristics will necessarily be in whieh they live and work. For the seas this information must describe the air above the sea, included.
Download or read book The Northern North Atlantic written by Priska Schäfer and published by Springer Science & Business Media. This book was released on 2001-04-02 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt: The northern North Atlantic is one of the regions most sensitive to past and present global changes. This book integrates the results of an interdisciplinary project studying the properties of the Greenland-Iceland-Norwegian Seas and the processes of pelagic and benthic particle formation, particle transport, and deposition in the deep-sea sediments. Ice-related and biogeochemical processes have been investigated to decipher the spatial and temporal variability of the production and fate of organic carbon in this region. Isotopic stratigraphy, microfossil assemblages and paleotemperatures are combined to reconstruct paleoceanographic conditions and to model past climatic changes in the Late Quaternary. The Greenland-Iceland-Norwegian Seas can now be considered one of the best studied subbasins of the world`s oceans.
