Download or read book Structure and Variability of Antarctic Circumpolar Current in the Indian Ocean Sector written by Hai Jian Toh and published by . This book was released on 2013 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Structure and Variability of the Antarctic Circumpolar Current written by E.I. Sarukhanyan and published by CRC Press. This book was released on 2007-02-07 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work covers horizontal circulation in the Southern Ocean, spatial structure of Antarctic Circumpolar Current (ACC) from experimental results, transport of waters in ACC systems and variability of ACC.

Download or read book Struktura i Izmenchivost Antarkticheskogo Tsirkumpolyarnogo Techniya written by Edouard Iosifovitch Saroukhanian and published by . This book was released on 1985 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Frontal Structure of the Antarctic Circumpolar Current in the South Indian Ocean written by M. D. Sparrow and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Antarctic Circumpolar Current System and Its Response to Atmospheric Variability written by Yong Sun Kim and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Antarctic Circumpolar Current (ACC) is well known for its multiple bands with large meridional property gradients in the upper waters, each associated with a deep-reaching current core. A revised nineteen-year time series (1992?2011) of altimeter data from the CNES/CLS AVISO is analyzed to identify and trace the spatial distribution of ACC fronts. Specific contours of sea surface height (SSH) are selected within narrow continuous bands of relative maxima SSH slope in the Southwest Atlantic Ocean sector, where they closely follow the distribution of ACC fronts derived from inspection of concurrent high-resolution profile data at hydrographic stations. When applied to the full circumpolar belt, the frontal distribution derived from these new altimeter-based indicators also agrees well with the traces of current jets and in-situ dynamic height fields calculated from concurrent Argo profile data. The temporal variability of ACC fronts is analyzed in relation to dominant modes of atmospheric forcing variability in the Southern Ocean. All three ACC fronts have experienced large seasonal to decadal variability throughout the satellite altimetry era. The general seasonal tendency for each of these jets, with respect to long-term mean positions, is to be located farther to the south during the austral summer and to north in the winter. Circumpolar-mean annual frontal locations show a consistent linear trend of southward migration. However, the estimated decadal variability of the frontal distributions is highly localized, and due to selective response mechanisms to atmospheric variability. A persistent poleward drift of ACC fronts is observed in the Indian sector consistent with increasing sea surface temperature trends. In contrast, a vacillation in the meridional location of ACC fronts is observed in the Pacific sector in association to minor sea surface cooling trends. Therefore, unlike in the Indian sector, the regional Pacific Ocean response is significantly sensitive to dominant atmospheric forcing indices. Mesoscale eddies derived from instabilities at strong current cores are successfully identified with specific SSH gradient criteria. The new estimates of rings population in the Southern Ocean are tightly linked to interannual to decadal atmospheric variability. Increased number of mesoscale eddies correlate with positive SAM forcing about two years earlier, or negative ENSO forcing two to three months earlier. These cross-correlations might explain a prominent peak in rings abundance estimated during 2000 and 2001, and the short-lived maximum that appeared in 2010. There are no persistent trends in the estimated sea surface slope across Drake Passage, and therefore neither in the transport of the ACC. High cross-correlation between the abundance of mesoscale eddies and atmospheric forcing suggests that the overall ACC system is in an eddy-saturated state. However, Drake Passage positive sea level slope anomalies were two-year lagged with negative SAM forcing and with positive ENSO events. These regional responses are characteristic of eastward-propagating signals from a buoyancy-dominated Pacific sector of the Southern Ocean. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/148046

Download or read book Ocean Currents written by Robert Marsh and published by Elsevier. This book was released on 2021-06-30 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ocean Currents: Physical Drivers in a Changing World opens with a general introduction to the character, measurement, and simulation of ocean currents, leading to a physical and dynamical framework for understanding the wide variety of flows encountered in the oceans. The book comprises chapters covering distinct aspects of contrasting ocean currents: broad and slow, deep and shallow, narrow and swift, large scale and small scale, low latitudes and high latitudes, and moving in horizontal and vertical planes. Through this approach the authors cover a wide range of applications, from local to global, with considerable geographical context. - Provides analyses of ocean observations and numerical model simulations, highlighting the pathways and drift associated with ocean currents, around the World Ocean, linked to online exercises for instructors and students that extend this perspective - Presents applications to natural phenomena, showing how ocean currents shape marine ecosystems, helping researchers understand the distribution and adaptation of life in the oceans - Addresses societal challenges, specifically how ocean currents disperse pollutants (e.g. plastic) from coastal sources and how the global ocean circulation is central to our changing climate, helping students and researchers develop an interdisciplinary approach to global environmental change

Download or read book Polar Environments and Global Change written by Roger G. Barry and published by Cambridge University Press. This book was released on 2018-08-09 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surveys atmospheric, oceanic and cryospheric processes, present and past conditions, and changes in polar environments.

Download or read book Oceanography of the Ross Sea Antarctica written by Giancarlo Spezie and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: The era of the exploration of the World Ocean is not yet over: some areas still lack an adequate number of observations. The relationships between the physical, chemical and biological processes, which sustain the life on this planet, are not yet fully understood. In short, knowledge of the oceans is still far from satisfactory. This book covers an important period in the study of one of the last investigated areas of the World Ocean: the Ross Sea, Antarctica. During the 1990s, long-term experiments were conducted in this area as part of the Climatic Long-term Interaction for the Mass balance in Antarctica (CLIMA) project of the Italian National Programme for Antarctic Research (PNRA), providing a wealth of oceanographic information. This book is an outcome of the CLIMA field obser vations and international collaborations with the most important programmes in the Ross Sea-Southern Ocean area. It contributes to the st!ldies of the spatial and temporal variability of Ross Sea water masses and circulation and their relation ship with the Southern Ocean circulation. A comprehensive review of historical data is offered, and new data sets are analysed. The studies presented in this book show that much progress has been achieved during the last decade, but large gaps in our understanding of the physical processes in the Ross Sea are still to be filled. However, these studies contribute significantly to the investigation of some specific aspects regarding the circula tion of the main water masses.

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 The Agulhas Current written by Johann R.E. Lutjeharms and published by Springer Science & Business Media. This book was released on 2006-08-26 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on the research findings of 60 years, the author describes the origins of the Agulhas Current, its behaviour, its influence on the adjacent continental shelf, its effect on local weather and its role in linking the Indian and Atlantic Oceans. The text is well-illustrated and includes asides on the history of research on the Current. An exhaustive bibliography gives easy access to present knowledge on this important current system.

Download or read book Antarctic Ocean and Resources Variability written by Dietrich Sahrhage and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the intensification of research activities in the Southern Ocean in recent years, both at national levels and through international cooperation in such projects as BIOMASS with its FIBEX and SIBEX phases, the need was felt increasingly for closer collaboration between biologists, meteorologists, and oceanographers in the study of the interaction between the atmospheric forces, the water masses, and the living resources. Better knowledge in this regard is not only of scientific interest but also of practical importance, especially for the management of the resources and the protection of the Antarctic marine ecosystem. As a follow-up on a recommendation by the IOC Program Group for the Southern Oceans made in March 1983, the Intergovernmental Oceanographic Commission organized a meeting of experts on oceanography related to the dynamics of the Antarctic ecosystems. During this meeting, held in Kiel, Federal Republic of Ger many, in May 1984, biologists and oceanographers involved in BIOMASS activities met with the oceanographers of SCOR Working Group 74 to discuss ways and means for additional physical and chemical observations in the oceanographic research within BIOMASS. It was the time when large fluctuations in the distribution of krill with subsequent detrimental effects on predator species dependent on krill had just been observed, and the question arose whether this was possibly the result of changes in the Antarctic water circulation.

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 Antarctic Peninsula Region of the Southern Ocean written by Eugene G. Morozov and published by Springer Nature. This book was released on 2022-01-01 with total page 455 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is based on results from the Russian expedition in the region of the Antarctic Peninsula and Powell Basin in the northern part of the Weddell Sea, as well as on the review of earlier research in the region. The main goal of the research was to collect the newest data and study the physical properties and ecology of this key region of the Southern Ocean. Data analysis is supplemented with numerical modeling of the atmosphere-ocean interaction and circulation in the adjacent region, including research on rogue waves. The focus of the study was the Antarctic Circumpolar Current, currents and water properties in the Bransfield Strait and Antarctic Sound, properties of seawater, currents, ecosystem and biological communities in the Powell Basin of the northwestern Weddell Sea, and their variations. An attempt is made to reveal the role of various components of the Antarctic environment in the formation of biological productivity and maintenance of the Antarctic krill population. This is especially important as in the last decades the Antarctic environment has experienced significant changes related to the global climatic trends.

Download or read book Understanding Transport Variability of the Antarctic Circumpolar Current Using Ocean Bottom Pressure written by Jessica Makowski and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous studies have suggested that ocean bottom pressure (OBP) can be used to measure the transport variability of the Antarctic Circumpolar Current (ACC). The OBP observations from the Gravity Recovery and Climate Experiment (GRACE) are used to calculate transport along the choke point between Antarctica and Australia. Statistical analysis will be conducted to determine the uncertainty of the GRACE observations using a simulated data set. There has been some evidence to suggest that Southern Hemisphere winds and the Southern Annular Mode (SAM) or the Antarctic Oscillation (AAO) play a significant role in accelerating/decelerating ACC transport, along with some contribution from buoyancy forcing. We will examine whether average zonal wind stress, wind stress curl, local zonal winds, or the SAM are representative of the low frequency zonal mass transport variability. Preliminary studies suggest that seasonal variation in transport across the Australia-Antarctica choke point is driven by winds along and north of the northern front of the ACC, the Sub Tropical front (STF). It also appears that interannual variations in transport are related to wind variations centered south of the Sub Antarctic Front (SAF). We have observed a strong negative correlation/positive correlation across the STF of the ACC in the Indian Ocean, which suggests wind stress curl may also be responsible for transport variations.

Download or read book Dynamics of the Antarctic Circumpolar Current written by Sarah Tragler Gille and published by . This book was released on 1995 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Geosat altimeter data and numerical model output are used to examine the circulation and dynamics of the Antarctic Circumpolar Current (ACC). The mean sea surface height across the ACC has been reconstructed from height variability measured by the Geosat altimeter, without assuming prior knowledge of the geoid. For this study, an automated technique has been developed to estimate mean sea surface height for each satellite ground track using a meandering Gaussian jet model, and errors have been estimated using Monte Carlo simulation. The results are objectively mapped to produce a picture of the mean Subantarctic and Polar Fronts, which together comprise the major components of the ACC. The locations of the fronts are consistent with in situ observations and indicate that the fronts are substantially steered by bathymetry. The jets have an average Gaussian width of about 44 km in the meridional direction and meander about 75 km to either side of their mean locations. The width of the fronts is proportional to 1/f, indicating that with constant stratification, the width is proportional to the baroclinic. Rossby radius. The average height difference across the Subantarctic Front (SAF) is 0.7 m and across the Polar Front (PF) 0.6 m. The mean widths of the fronts are correlated with the size of the baroclinic Rossby radius. The meandering jet model explains between 40% and 70% of the height variance along the jet axes. Bathymetric constrictions are associated with increased eddy variability, a smaller percentage of which may be explained by the meandering of the ACC fronts, indicating that propagating eddies and rings may be spawned at topographic features. Detailed examination of spatial and temporal variability in the altimeter data indicates a spatial decorrelation scale of 85 km and a temporal e-folding scale of 34 days. The sea surface height variability is objectively mapped using these scales to define autocovariance functions. The resulting maps indicate substantial evidence of mesoscale eddy activity. Over 17-day time intervals, meanders of the PF and SAF appear to elongate, break off as rings, and propagate. Statistical analysis of ACC variability from altimeter data is conducted using empirical orthogonal functions (EOFs). The first mode EOF describes 16% of the variance in total sea surface height across the ACC; reducing the domain into basin scales does not significantly increase the variance represented by the first EOF, suggesting that the scales of motion are relatively short, and may be determined by local instability mechanisms rather than larger basin scale processes. Likewise, frequency domain EOFs indicate no statistically significant traveling wave modes. The momentum balance of the ACC has been investigated using both output from a high resolution primitive equation model and sea surface height measurements from the Geosat altimeter. In the Semtner-Chervin general circulation model, run with approximately quarter-degree resolution and time varying ECMWF winds, topographic form stress is the dominant process balancing the surface wind forcing. Detailed examination of form stress in the model indicates that it is due to three large topographic obstructions located at Kerguelen Island, Campbell Plateau, and Drake Passage. In order to reduce the effects of standing eddies, the model momentum balance is considered in stream coordinates; vertically integrated through the entire water column, topographic form drag is the dominant balance for wind stress. However, at mid-depth the cross-stream momentum transfer is dominated by horizontal biharmonic friction. In the upper ocean, horizontal friction, mean momentum flux divergence, transient momentum flux divergence, and mean vertical flux divergence all contribute significantly to the momentum balance. Although the relative importance of individual terms in the momentum balance does not vary substantially along streamlines, elevated levels of eddy kinetic energy are associated with the three major topographic features. In contrast, altimeter data show elevated energy levels at many more topographic features of intermediate scales, suggesting that smaller topographic effects are better able to communicate with the surface in the real ocean than in the model. Transient Reynolds stress terms play a small role in the the overall momentum balance; nonetheless, altimeter and model measurements closely agree, and suggest that transient eddies tend to accelerate the mean flow, except in the region between the major fronts which comprise the ACC. Potential vorticity is considered in the model output along Montgomery streamfunction. Even at about 1000 m depth, it varies in response to wind forcing, largely as a result of changes in vertical stratification, indicating that forcing and dissipation do not locally balance in the Southern Ocean. In order to compare model and altimeter potential vorticity estimates, two different proxies for potential vorticity on surface streamlines are considered. Both proxies show very similar results for model and altimeter, suggesting that differences in surface streamlines estimated by the altimeter and the model are not significant in explaining the Southern Ocean flow. The proxies are both roughly conserved along surface height contours but undergo substantial jumps near topographic features. However, they cannot capture stratification changes which may be critically important to the overall potential vorticity balance.