Download or read book Stochastically forced variability in the antarctic circumpolar current written by and published by . This book was released on 1997 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 Ocean Forecasting written by Nadia Pinardi and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Advanced Study Courses in the field of Marine Science and Technology were part of the training programme developed from 1989 until 1999 within MAST, the Marine Science and Technology Programme of the European Union. They were related to the core topics of MAST Programme, marine systems research, extreme marine environments, regional Sea research, coastal systems research and engineering, and marine technology. The main objectives of these study courses were to further advance education in topics at the forefront of scien tific and technological development in Europe, and to improve the communication between students and experienced scientists on a European and international level. Over the years the Programme sponsored around 30 Advanced Study Courses. They took place in ten different member states of the European Union and their contribution in the formation of a European scientific community was significant. They also encouraged exchanges and contacts with several countries around the world such as United States, the third Mediterranean countries and others. The Course on Ocean Forecasting was one ofthe most successful with regard to its con tent, number of applications for participation and students satisfaction. When considering the need for the Advanced Study Course on Ocean Forecast ing, it is important to remember that the Oceans and Seas have always played a central role throughout the history of mankind. This is seen from the times of the ancient civilizations ofEgypt and Greece with the Phoenician traders, to the Viking voyages of exploration and discovery in medieval times.

Download or read book Frontiers of Climate Modeling written by J. T. Kiehl and published by Cambridge University Press. This book was released on 2011-06-30 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: The physics and dynamics of the atmosphere and atmosphere-ocean interactions provide the foundation of modern climate models, upon which our understanding of the chemistry and biology of ocean and land surface processes are built. Originally published in 2006, Frontiers of Climate Modeling captures developments in modeling the atmosphere, and their implications for our understanding of climate change, whether due to natural or anthropogenic causes. Emphasis is on elucidating how greenhouse gases and aerosols are altering the radiative forcing of the climate system and the sensitivity of the system to such perturbations. An expert team of authors address key aspects of the atmospheric greenhouse effect, clouds, aerosols, atmospheric radiative transfer, deep convection dynamics, large scale ocean dynamics, stratosphere-troposphere interactions, and coupled ocean-atmosphere model development. The book is an important reference for researchers and advanced students interested in the forces driving the climate system and how they are modeled by climate scientists.

Download or read book Climate Change in the Polar Regions written by John Turner and published by Cambridge University Press. This book was released on 2011-05-12 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive, up-to-date account of polar climate change over the last one million years for researchers and advanced students in polar science.

Download or read book Ocean Circulation and Climate written by Mojib Latif and published by Elsevier Inc. Chapters. This book was released on 2013-10-22 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

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 Marine Climate and Climate Change written by Ralf Weisse and published by Springer Science & Business Media. This book was released on 2010-01-08 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: Marine environmental conditions such as storms, storm surges and wave heights are directly experienced by, for example, off-shore operations or coastal populations. The authors review and bring together the state-of-the-art and present day knowledge about historical changes, recent trends and concepts on how marine environmental conditions may change in the future as well as discuss models and data problems.

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 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.

Download or read book Proceedings of the First WCRP International Conference on Reanalyses Silver Spring Maryland USA 27 31 October 1997 written by and published by . This book was released on 1998 with total page 548 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Future of the World s Climate written by Ann Henderson-Sellers and published by Elsevier. This book was released on 2012-01-31 with total page 678 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The study of climate today seems to be dominated by global warming, but these predictions of climatic models must be placed in their geological, paleo-climatic, and astronomical context to create a complete picture of the Earth's future climate. The Future of the World's Climate presents that perspective with data and projections that have emerged from more technologically advanced and accurate climate modeling"--Publisher's website.

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 Journal of Physical Oceanography written by and published by . This book was released on 2006 with total page 1274 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Variability and Dynamics of the Antarctic Circumpolar Current South of Africa Using Proxy Techniques written by and published by . This book was released on 2009 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Variability of the southern Antarctic Circumpolar Current front north of South Georgia written by S.E. THORPE and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: