Download or read book The dynamical controls on the antarctic circumpolar current with the use of general circulation models written by Anita Grezio and published by . This book was released on 2002 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Dynamical Controls on the Antarctic Circumpolar Current with the Use of General Circulation Model written by Anita Grezio and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interactions between thermohaline and wind driven circulations and their relevance to the dynamics of the Antarctic Circumpolar Current in a coarse resolution global ocean general circulation model written by W. CAI and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ocean Mixing written by Michael Meredith and published by Elsevier. This book was released on 2021-09-16 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ocean Mixing: Drivers, Mechanisms and Impacts presents a broad panorama of one of the most rapidly-developing areas of marine science. It highlights the state-of-the-art concerning knowledge of the causes of ocean mixing, and a perspective on the implications for ocean circulation, climate, biogeochemistry and the marine ecosystem. This edited volume places a particular emphasis on elucidating the key future questions relating to ocean mixing, and emerging ideas and activities to address them, including innovative technology developments and advances in methodology. Ocean Mixing is a key reference for those entering the field, and for those seeking a comprehensive overview of how the key current issues are being addressed and what the priorities for future research are. Each chapter is written by established leaders in ocean mixing research; the volume is thus suitable for those seeking specific detailed information on sub-topics, as well as those seeking a broad synopsis of current understanding. It provides useful ammunition for those pursuing funding for specific future research campaigns, by being an authoritative source concerning key scientific goals in the short, medium and long term. Additionally, the chapters contain bespoke and informative graphics that can be used in teaching and science communication to convey the complex concepts and phenomena in easily accessible ways. - Presents a coherent overview of the state-of-the-art research concerning ocean mixing - Provides an in-depth discussion of how ocean mixing impacts all scales of the planetary system - Includes elucidation of the grand challenges in ocean mixing, and how they might be addressed
Download or read book Dynamics of a Quasigeostrophic Antarctic Circumpolar Current written by Louis-Philippe Nadeau and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Contributions to the Dynamics of the Antarctic Circumpolar Current A C C II written by Takashi Ichiye and published by . This book was released on 1975 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Non-dimensional equations of motion are derived for the A.C.C. of the barotropic mode, including the bottom friction and the horizontal eddy viscosity. Integration of the vorticity equation leads to the zeroth order stream function which is dependent only on depth divided by Coriolis' parameter. Integration of the momentum equation along a streamline yields the relation between the momentum input by wind stress and its dissipation by the bottom friction and by the horizontal eddy viscosity. The relation determines the magnitude of the stream function. It also explains differences in the total transport of the A.C.C. obtained by Kamenkovich (1962) and by Bryan and Cox (1972).
Download or read book Ocean Circulation and Climate written by and published by Elsevier. This book was released on 2001-03-27 with total page 737 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book represents all the knowledge we currently have on ocean circulation. It presents an up-to-date summary of the state of the science relating to the role of the oceans in the physical climate system.The book is structured to guide the reader through the wide range of World Ocean Circulation Experiment (WOCE) science in a consistent way. Cross-references between contributors have been added, and the book has a comprehensive index and unified reference list.The book is simple to read, at the undergraduate level. It was written by the best scientists in the world who have collaborated to carry out years of experiments to better understand ocean circulation.
Download or read book The Variability and Dynamics of the Antartic Circumpolar Current South of Africa Using Proxy Techniques written by Sebastiaan Swart and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The general circulation of the Southern Ocean is dominated by the eastward flowing Antarctic Circumpolar Current (ACC). This is a continuous feature linking the three major ocean basins and thus forms a vital link in the transport of heat and salt on a global scale. These exchanges provide a vital mechanism for the global thermohaline circulation (THC), which regulates the Earthâs climate. In the high latitudes, where conditions are hostile, routine hydrographic observations are scarce resulting in a poor understanding of the physical and dynamic processes controlling the variability of the ACC and its influence on the THC. The GoodHope program launched in early 2004 aimed to establish an intensive monitoring platform that would provide detailed information on the physical structure and volume flux of water masses south of Africa. Sustained observations along the GoodHope cruise track provide the means to monitor the vertical structure and variability of the ACC and its associated fronts south of Africa. Such intense monitoring has been under way in the Drake Passage and south of Australia since the 1970s. A major objective of this thesis is to provide sound estimates of ACC transport and variability using both in situ measurements and remote sensing techniques. These estimates are crucial in understanding the role the ACC plays in the global thermohaline circulation (THC) and how the region south of Africa acts as a major conveyor of heat and salt to the higher latitudes. Baroclinic transports of the ACC, relative to 2500 dbar, are calculated from altimetry data alone. These transports agree with simultaneous observed estimates (rms difference in net transport is 5.2 Sv). These observations suggest that sea level anomalies largely reflect baroclinic transport variations above 2500 dbar. The transports contribution per ACC front shows that the SAF is responsible for the highest variability signals (>50%) even though its net transport contribution to
Download or read book Structure and Variability of the Antarctic Circumpolar Current written by Ėduard Iosifovich Sarukhani︠a︡n and published by . This book was released on 1985 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Dynamics of the Ross Gyre written by Yang Wang and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Formation of cold, dense waters south of the Antarctic Circumpolar Current (ACC) is one of the main drivers of the global overturning circulation, with major implications on the earth's climate. A key region where the densest waters on earth are formed is the Ross Sea which is separated from the ACC by the Ross Gyre. The strength and variability of the Ross Gyre circulation impact the formation and export of dense water, and it is therefore important to understand its circulation and dynamics. Observations in the Ross Gyre are limited because of its remote location and the severe weather conditions. Furthermore, the ice cover limits the application of remote sensing techniques. Quantitative estimates of the gyre's strength are difficult to obtain from hydrographic observations alone due to the limited sampling and the relatively weak stratification. In this dissertation, we use a combination of observations and modeling studies to a) provide an estimate of the strength and variability of the Ross Gyre transport and b) investigate the relative contributions of the wind and buoyancy forcing, eddies, and the presence of ACC to the Ross Gyre circulation. We find that the mean transport of the Ross Gyre can be as high as ~45 Sv, about twice of the typical estimate ~20 Sv reported in the literature. Sensitivity experiments to wind and buoyancy forcing, nonlinear terms, and the ACC were performed with a regional configuration of the Hybrid Coordinate Ocean Model (HYCOM). The numerical experiments show that the Ross Gyre, and its variability, are primarily wind-driven. The ACC is responsible for part of the recirculation. Buoyancy and nonlinearity/eddy do not appear to play a major role in the gyre dynamics.
Download or read book Report written by and published by . This book was released on with total page 510 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ocean Dynamics and the Carbon Cycle written by Richard G. Williams and published by Cambridge University Press. This book was released on 2011-07-14 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook for advanced undergraduate and graduate students presents a multidisciplinary approach to understanding ocean circulation and how it drives and controls marine biogeochemistry and biological productivity at a global scale. Background chapters on ocean physics, chemistry and biology provide students with the tools to examine the range of large-scale physical and dynamic phenomena that control the ocean carbon cycle and its interaction with the atmosphere. Throughout the text observational data is integrated with basic physical theory to address cutting-edge research questions in ocean biogeochemistry. Simple theoretical models, data plots and schematic illustrations summarise key results and connect the physical theory to real observations. Advanced mathematics is provided in boxes and appendices where it can be drawn on to assist with the worked examples and homework exercises available online. Further reading lists for each chapter and a comprehensive glossary provide students and instructors with a complete learning package.
Download or read book Uncertainty Quantification in Ocean State Estimation written by Alexander G. Kalmikov and published by . This book was released on 2013 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantifying uncertainty and error bounds is a key outstanding challenge in ocean state estimation and climate research. It is particularly difficult due to the large dimensionality of this nonlinear estimation problem and the number of uncertain variables involved. The "Estimating the Circulation and Climate of the Oceans" (ECCO) consortium has developed a scalable system for dynamically consistent estimation of global time-evolving ocean state by optimal combination of ocean general circulation model (GCM) with diverse ocean observations. The estimation system is based on the "adjoint method" solution of an unconstrained least-squares optimization problem formulated with the method of Lagrange multipliers for fitting the dynamical ocean model to observations. The dynamical consistency requirement of ocean state estimation necessitates this approach over sequential data assimilation and reanalysis smoothing techniques. In addition, it is computationally advantageous because calculation and storage of large covariance matrices is not required. However, this is also a drawback of the adjoint method, which lacks a native formalism for error propagation and quantification of assimilated uncertainty. The objective of this dissertation is to resolve that limitation by developing a feasible computational methodology for uncertainty analysis in dynamically consistent state estimation, applicable to the large dimensionality of global ocean models. Hessian (second derivative-based) methodology is developed for Uncertainty Quantification (UQ) in large-scale ocean state estimation, extending the gradient-based adjoint method to employ the second order geometry information of the model-data misfit function in a high-dimensional control space. Large error covariance matrices are evaluated by inverting the Hessian matrix with the developed scalable matrix-free numerical linear algebra algorithms. Hessian-vector product and Jacobian derivative codes of the MIT general circulation model (MITgcm) are generated by means of algorithmic differentiation (AD). Computational complexity of the Hessian code is reduced by tangent linear differentiation of the adjoint code, which preserves the speedup of adjoint checkpointing schemes in the second derivative calculation. A Lanczos algorithm is applied for extracting the leading rank eigenvectors and eigenvalues of the Hessian matrix. The eigenvectors represent the constrained uncertainty patterns. The inverse eigenvalues are the corresponding uncertainties. The dimensionality of UQ calculations is reduced by eliminating the uncertainty null-space unconstrained by the supplied observations. Inverse and forward uncertainty propagation schemes are designed for assimilating observation and control variable uncertainties, and for projecting these uncertainties onto oceanographic target quantities. Two versions of these schemes are developed: one evaluates reduction of prior uncertainties, while another does not require prior assumptions. The analysis of uncertainty propagation in the ocean model is time-resolving. It captures the dynamics of uncertainty evolution and reveals transient and stationary uncertainty regimes. The system is applied to quantifying uncertainties of Antarctic Circumpolar Current (ACC) transport in a global barotropic configuration of the MITgcm. The model is constrained by synthetic observations of sea surface height and velocities. The control space consists of two-dimensional maps of initial and boundary conditions and model parameters. The size of the Hessian matrix is 0(1010) elements, which would require 0(60GB) of uncompressed storage. It is demonstrated how the choice of observations and their geographic coverage determines the reduction in uncertainties of the estimated transport. The system also yields information on how well the control fields are constrained by the observations. The effects of controls uncertainty reduction due to decrease of diagonal covariance terms are compared to dynamical coupling of controls through off-diagonal covariance terms. The correlations of controls introduced by observation uncertainty assimilation are found to dominate the reduction of uncertainty of transport. An idealized analytical model of ACC guides a detailed time-resolving understanding of uncertainty dynamics. Keywords: Adjoint model uncertainty, sensitivity, posterior error reduction, reduced rank Hessian matrix, Automatic Differentiation, ocean state estimation, barotropic model, Drake Passage transport.
Download or read book Ocean Circulation written by Open Open University and published by Elsevier. This book was released on 2001-09-17 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This second edition retains the general structure of the first edition, buthas been updated in the light of recent oceanographic research, and improvedas a teaching text on the basis of feedback from past students and otherreaders.Notable additions include new sections addressing the topic ofnumerical modelling, and more discussion of natural oscillations in theocean-atmosphere system (previously confined to the El Niño phenomenon). Inparticular, the Chapter on the North Atlantic now includes a discussion ofthe North Atlantic Oscillation, as well as of the Great Salinity Anomaly. Inthe final Chapter, treatment of water mass formation has been updated toreflect recent ideas about the processes involved and how they relate toclimatic change over different time-scales, from decades to millennia.High quality full colour diagramsSubstantial chapter summaries ideal for revisionAnswers, hints and notes for questions at back of the book
Download or read book The Antarctic Circumpolar Current in the Drake Passage written by Ramiro Ferrari and published by . This book was released on 2013 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis examines Antarctic Circumpolar Current (ACC) circulation and the mechanisms of meridional heat transport in Drake Passage. In order to achieve these goals we used in situ measurements collected during the DRAKE project (from January 2006 to March 2009; DRAKE 2006-9), available observations from the historical DRAKE 79 experiment, satellite altimetry data (since 1993) and high resolution model outputs (ORCA 12, MERCATOR). DRAKE 2006-9 current meter records, obtained from a current meter array deployed on the eastern side of the Shackleton Fracture Zone (SFZ), suggested the existence of a permanent strong deep cyclonic circulation in the northeastern part of the Yaghan Basin and in the Ona Basin. Mooring data also revealed a vertical consistency of the velocity and temperature variations. However, the rotation of the mean velocity vector with depth indicated consistent downwelling through the entire water column practically all along the mooring line. Near-surface current meter velocities provided an unprecedented opportunity to evaluate the altimetric velocities in this region. Comparison between in situ velocities and velocities derived from altimetry has shown good agreement allowing to further interpret observations at isolated mooring sites and to put them in the context of the 18-year-long satellite record. Altimetry helped to identify a dominant spatial structure associated to the presence of a strong southward meander of the Subantarctic Front in Yaghan Basin. Furthermore, it provided an accurate documentation concerning how the major topographic features control the mean location and meandering of the Antarctic Circumpolar Current frontal branches. In situ temperature and velocity time series from the DRAKE 2006-9 project were combined with the year-long historical DRAKE 79 experiment data set in order to analyse the eddy and mean flow contributions to the meridional heat flux across in the Drake Passage. Estimated cross-stream heat fluxes caused by the rotation of the mean flow with depth were found to be at least an order of magnitude larger than eddy heat fluxes. Equatorward heat fluxes caused by the mean flow found downstream the SFZ were in agreement with the general downwelling observed along the DRAKE 2006-9 project mooring array. Upstream the SFZ, however, the distribution of equatorward and poleward fluxes was puzzling. This distribution was analyzed using model outputs. Heat flux estimates due to the mean flow from the model outputs were similar to those obtained from in situ data and exhibited small spatial scales. The rough topography in Drake Passage likely promotes associated small spatial scales of vertical velocities and heat fluxes. The model-estimated heat flux due to the mean flow across the Southern ACC Front in Drake Passage (covering about 3% of the circumpolar longitudes between 48°W and 64°W) is thus on the order of 10% of the heat lost to the atmosphere south of 60°S.
Download or read book Antarctic Sea Ice Variability in the Southern Ocean Climate System written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2017-04-24 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sea ice surrounding Antarctica has increased in extent and concentration from the late 1970s, when satellite-based measurements began, until 2015. Although this increasing trend is modest, it is surprising given the overall warming of the global climate and the region. Indeed, climate models, which incorporate our best understanding of the processes affecting the region, generally simulate a decrease in sea ice. Moreover, sea ice in the Arctic has exhibited pronounced declines over the same period, consistent with global climate model simulations. For these reasons, the behavior of Antarctic sea ice has presented a conundrum for global climate change science. The National Academies of Sciences, Engineering, and Medicine held a workshop in January 2016, to bring together scientists with different sets of expertise and perspectives to further explore potential mechanisms driving the evolution of recent Antarctic sea ice variability and to discuss ways to advance understanding of Antarctic sea ice and its relationship to the broader ocean-climate system. This publication summarizes the presentations and discussions from the workshop.
Download or read book U S WOCE Report written by and published by . This book was released on 1995 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
