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EBookClubs

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Book Naval Research Reviews

Download or read book Naval Research Reviews written by and published by . This book was released on 1999 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Advances in Neural Networks ISNN 2009

Download or read book Advances in Neural Networks ISNN 2009 written by Wen Yu and published by Springer Science & Business Media. This book was released on 2009-05-06 with total page 1270 pages. Available in PDF, EPUB and Kindle. Book excerpt: The three volume set LNCS 5551/5552/5553 constitutes the refereed proceedings of the 6th International Symposium on Neural Networks, ISNN 2009, held in Wuhan, China in May 2009. The 409 revised papers presented were carefully reviewed and selected from a total of 1.235 submissions. The papers are organized in 20 topical sections on theoretical analysis, stability, time-delay neural networks, machine learning, neural modeling, decision making systems, fuzzy systems and fuzzy neural networks, support vector machines and kernel methods, genetic algorithms, clustering and classification, pattern recognition, intelligent control, optimization, robotics, image processing, signal processing, biomedical applications, fault diagnosis, telecommunication, sensor network and transportation systems, as well as applications.

Book Physical Oceanography of the Indian Ocean

Download or read book Physical Oceanography of the Indian Ocean written by Friedrich A. Schott and published by . This book was released on 2003 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Journal of Atmospheric and Oceanic Technology

Download or read book Journal of Atmospheric and Oceanic Technology written by and published by . This book was released on 2000 with total page 832 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Temporal Changes in Eddy Energy of the Oceans

Download or read book Temporal Changes in Eddy Energy of the Oceans written by Detlef Stammer and published by . This book was released on 1998 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Optimal Determination of Global Tropospheric OH Concentrations Using Multiple Trace Gases

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.

Book On Convective Mixing and the Thermohaline Circulation

Download or read book On Convective Mixing and the Thermohaline Circulation written by Jochem Marotzke and published by . This book was released on 1998 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Representation of Eddies in Climate Models by a Potential Vorticity Flux

Download or read book Representation of Eddies in Climate Models by a Potential Vorticity Flux written by Richard M. Wardle and published by . This book was released on 1999 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis addresses the parameterization of the heat and momentum transporting properties of eddy motions for use in primitive equation climate models. The approach is to transform the primitive equations to yield the altered.

Book Terrestrial Sources and Sinks of Atmospheric Methyl Bromide

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

Book Interhemispheric Thermohaline Circulation in a Coupled Box Model

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.