Academic literature on the topic 'Antarctic Ocean Climate'
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Journal articles on the topic "Antarctic Ocean Climate"
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Singh, Hansi K. A., Cecilia M. Bitz, and Dargan M. W. Frierson. "The Global Climate Response to Lowering Surface Orography of Antarctica and the Importance of Atmosphere–Ocean Coupling." Journal of Climate 29, no. 11 (May 20, 2016): 4137–53. http://dx.doi.org/10.1175/jcli-d-15-0442.1.
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Abstract A global climate model is used to study the effect of flattening the orography of the Antarctic Ice Sheet on climate. A general result is that the Antarctic continent and the atmosphere aloft warm, while there is modest cooling globally. The large local warming over Antarctica leads to increased outgoing longwave radiation, which drives anomalous southward energy transport toward the continent and cooling elsewhere. Atmosphere and ocean both anomalously transport energy southward in the Southern Hemisphere. Near Antarctica, poleward energy and momentum transport by baroclinic eddies strengthens. Anomalous southward cross-equatorial energy transport is associated with a northward shift in the intertropical convergence zone. In the ocean, anomalous southward energy transport arises from a slowdown of the upper cell of the oceanic meridional overturning circulation and a weakening of the horizontal ocean gyres, causing sea ice in the Northern Hemisphere to expand and the Arctic to cool. Comparison with a slab-ocean simulation confirms the importance of ocean dynamics in determining the climate system response to Antarctic orography. This paper concludes by briefly presenting a discussion of the relevance of these results to climates of the past and to future climate scenarios.
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Jun, Sang-Yoon, Joo-Hong Kim, Jung Choi, Seong-Joong Kim, Baek-Min Kim, and Soon-Il An. "The internal origin of the west-east asymmetry of Antarctic climate change." Science Advances 6, no. 24 (June 2020): eaaz1490. http://dx.doi.org/10.1126/sciadv.aaz1490.
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Recent Antarctic surface climate change has been characterized by greater warming trends in West Antarctica than in East Antarctica. Although this asymmetric feature is well recognized, its origin remains poorly understood. Here, by analyzing observation data and multimodel results, we show that a west-east asymmetric internal mode amplified in austral winter originates from the harmony of the atmosphere-ocean coupled feedback off West Antarctica and the Antarctic terrain. The warmer ocean temperature over the West Antarctic sector has positive feedback, with an anomalous upper-tropospheric anticyclonic circulation response centered over West Antarctica, in which the strength of the feedback is controlled by the Antarctic topographic layout and the annual cycle. The current west-east asymmetry of Antarctic surface climate change is undoubtedly of natural origin because no external factors (e.g., orbital or anthropogenic factors) contribute to the asymmetric mode.
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MACKENSEN, ANDREAS. "Changing Southern Ocean palaeocirculation and effects on global climate." Antarctic Science 16, no. 4 (November 30, 2004): 369–86. http://dx.doi.org/10.1017/s0954102004002202.
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Southern Ocean palaeocirculation is clearly related to the formation of a continental ice sheet on Antarctica and the opening of gateways between Antarctica and the Australian and South American continents. Palaeoenvironmental proxy records from Southern Ocean sediment cores suggest ice growth on Antarctica beginning by at least 40 million years (Ma) ago, and the opening of Tasmania–Antarctic and Drake Passages to deep-water flow around 34 and 31 ± 2 Ma, respectively. So, the Eocene/Oligocene transition appears to mark the initiation of the Antarctic Circumpolar Current and thus the onset of thermal isolation of Antarctica with a first major ice volume growth on East Antarctic. There is no evidence for a significant cooling of the deep ocean associated with this rapid (< 350 000 years) continental ice build-up. After a long phase with frequent ice sheets growing and decaying, in the middle Miocene at about 14 Ma, a re-establishment of an ice sheet on East Antarctica and the Pacific margin of West Antarctica was associated with an increased southern bottom water formation, and a slight cooling of the deep ocean, but with no permanent drop in atmospheric pCO2. During the late Pleistocene on orbital time scales a temporal correlation between changes in atmospheric pCO2 and proxy records of deep ocean temperatures, continental ice volume, sea ice extension, and deep-water nutrient contents is documented. I discuss hypotheses that call for a dominant control of glacial to interglacial atmospheric pCO2 variations by Southern Ocean circulation dynamics. Millennial to centennial climate variability is a global feature, but there is contrasting evidence from various palaeoclimate archives that indicate both interhemispheric synchrony and asynchrony. The role of the Southern Ocean, however, in triggering or modulating climate variability on these time scales only recently received some attention and is not yet adequately investigated.
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England, Matthew H., David K. Hutchinson, Agus Santoso, and Willem P. Sijp. "Ice–Atmosphere Feedbacks Dominate the Response of the Climate System to Drake Passage Closure." Journal of Climate 30, no. 15 (August 2017): 5775–90. http://dx.doi.org/10.1175/jcli-d-15-0554.1.
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The response of the global climate system to Drake Passage (DP) closure is examined using a fully coupled ocean–atmosphere–ice model. Unlike most previous studies, a full three-dimensional atmospheric general circulation model is included with a complete hydrological cycle and a freely evolving wind field, as well as a coupled dynamic–thermodynamic sea ice module. Upon DP closure the initial response is found to be consistent with previous ocean-only and intermediate-complexity climate model studies, with an expansion and invigoration of the Antarctic meridional overturning, along with a slowdown in North Atlantic Deep Water (NADW) production. This results in a dominance of Southern Ocean poleward geostrophic flow and Antarctic sinking when DP is closed. However, within just a decade of DP closure, the increased southward heat transport has melted back a substantial fraction of Antarctic sea ice. At the same time the polar oceans warm by 4°–6°C on the zonal mean, and the maximum strength of the Southern Hemisphere westerlies weakens by ≃10%. These effects, not captured in models without ice and atmosphere feedbacks, combine to force Antarctic Bottom Water (AABW) to warm and freshen, to the point that this water mass becomes less dense than NADW. This leads to a marked contraction of the Antarctic overturning, allowing NADW to ventilate the abyssal ocean once more. Poleward heat transport settles back to very similar values as seen in the unperturbed DP open case. Yet remarkably, the equilibrium climate in the closed DP configuration retains a strong Southern Hemisphere warming, similar to past studies with no dynamic atmosphere. However, here it is ocean–atmosphere–ice feedbacks, primarily the ice-albedo feedback and partly the weakened midlatitude jet, not a vigorous southern sinking, which maintain the warm polar oceans. This demonstrates that DP closure can drive a hemisphere-scale warming with polar amplification, without the presence of any vigorous Southern Hemisphere overturning circulation. Indeed, DP closure leads to warming that is sufficient over the West Antarctic Ice Sheet region to inhibit ice-sheet growth. This highlights the importance of the DP gap, Antarctic sea ice, and the associated ice-albedo feedback in maintaining the present-day glacial state over Antarctica.
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Jacka, T. H. "Antarctic and Southern Ocean Sea-Ice and Climate Trends." Annals of Glaciology 14 (1990): 127–30. http://dx.doi.org/10.3189/s0260305500008417.
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A computer-based climate monitoring project is described. Data sets include monthly and annual mean surface temperatures and pressures for occupied stations in Antarctica, the Southern Ocean and South Pacific Ocean; and monthly Antarctic sea-ice extent at each 10° of longitude.Simple statistical analyses of the data sets reveal a mean warming of ~0.15°C (10 a)−1 since the mid 1950s for Antarctic coastal stations and of ~0.04°C (10 a)−1 since the mid 1940s for the ocean stations. The sea-ice record from 1973 to 1988 reveals that the average northern ice limit has decreased at ~0.23°lat. (10 a)−1. Despite apparently compatible long-term trends of temperature and sea-ice extent, annual fluctuations of temperature and ice extent are highly variable and are not well correlated.
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Jacka, T. H. "Antarctic and Southern Ocean Sea-Ice and Climate Trends." Annals of Glaciology 14 (1990): 127–30. http://dx.doi.org/10.1017/s0260305500008417.
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A computer-based climate monitoring project is described. Data sets include monthly and annual mean surface temperatures and pressures for occupied stations in Antarctica, the Southern Ocean and South Pacific Ocean; and monthly Antarctic sea-ice extent at each 10° of longitude. Simple statistical analyses of the data sets reveal a mean warming of ~0.15°C (10 a)−1 since the mid 1950s for Antarctic coastal stations and of ~0.04°C (10 a)−1 since the mid 1940s for the ocean stations. The sea-ice record from 1973 to 1988 reveals that the average northern ice limit has decreased at ~0.23°lat. (10 a)−1. Despite apparently compatible long-term trends of temperature and sea-ice extent, annual fluctuations of temperature and ice extent are highly variable and are not well correlated.
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Pedro, J. B., T. D. van Ommen, S. O. Rasmussen, V. I. Morgan, J. Chappellaz, A. D. Moy, V. Masson-Delmotte, and M. Delmotte. "The last deglaciation: timing the bipolar seesaw." Climate of the Past Discussions 7, no. 1 (January 26, 2011): 397–430. http://dx.doi.org/10.5194/cpd-7-397-2011.
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Abstract. Precise information on the relative timing of north-south climate variations is a key to resolving questions concerning the mechanisms that force and couple climate changes between the hemispheres. We present a new composite record made from five well-resolved Antarctic ice core records that robustly represents the timing of regional Antarctic climate change during the last deglaciation. Using fast variations in global methane gas concentrations as time markers, the Antarctic composite is directly compared to Greenland ice core records, allowing a detailed mapping of the inter-hemispheric sequence of climate changes. Consistent with prior studies the synchronized records show that warming (and cooling) trends in Antarctica closely match cold (and warm) periods in Greenland on millennial timescales. For the first time, we also identify a sub-millennial component to the inter-hemispheric coupling: within the Antarctic Cold Reversal the strongest Antarctic cooling occurs during the pronounced northern warmth of the Bølling; warming then resumes in Antarctica during the Intra-Allerød Cold Period i.e. prior to the Younger Dryas stadial. There is little-to-no time lag between climate transitions in Greenland and opposing changes in Antarctica. Our results lend support to fast acting inter-hemispheric coupling mechanisms including recently proposed bipolar atmospheric teleconnections and/or rapid bipolar ocean teleconnections.
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Li, Xichen, David M. Holland, Edwin P. Gerber, and Changhyun Yoo. "Rossby Waves Mediate Impacts of Tropical Oceans on West Antarctic Atmospheric Circulation in Austral Winter." Journal of Climate 28, no. 20 (October 13, 2015): 8151–64. http://dx.doi.org/10.1175/jcli-d-15-0113.1.
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Abstract Recent studies link climate change around Antarctica to the sea surface temperature of tropical oceans, with teleconnections from the Pacific, Atlantic, and Indian Oceans making different contributions to Antarctic climate. In this study, the impacts of each ocean basin on the wintertime Southern Hemisphere circulation are identified by comparing simulation results using a comprehensive atmospheric model, an idealized dynamical core model, and a theoretical Rossby wave model. The results herein show that tropical Atlantic Ocean warming, Indian Ocean warming, and eastern Pacific cooling are all able to deepen the Amundsen Sea low located adjacent to West Antarctica, while western Pacific warming increases the pressure to the west of the international date line, encompassing the Ross Sea and regions south of the Tasman Sea. In austral winter, these tropical ocean basins work together linearly to modulate the atmospheric circulation around West Antarctica. Further analyses indicate that these teleconnections critically depend on stationary Rossby wave dynamics and are thus sensitive to the background flow, particularly the subtropical/midlatitude jet. Near these jets, wind shear is amplified, which strengthens the generation of Rossby waves. On the other hand, near the edges of the jets the meridional gradient of the absolute vorticity is also enhanced. As a consequence of the Rossby wave dispersion relationship, the jet edge may reflect stationary Rossby wave trains, serving as a waveguide. The simulation results not only identify the relative roles of each of the tropical ocean basins in the tropical–Antarctica teleconnection, but also suggest that a deeper understanding of teleconnections requires a better estimation of the atmospheric jet structures.
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Bintanja, R., G. J. van Oldenborgh, and C. A. Katsman. "The effect of increased fresh water from Antarctic ice shelves on future trends in Antarctic sea ice." Annals of Glaciology 56, no. 69 (2015): 120–26. http://dx.doi.org/10.3189/2015aog69a001.
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AbstractObservations show that, in contrast to the Arctic, the area of Antarctic sea ice has increased since 1979. A potential driver of this significant increase relates to the mass loss of the Antarctic ice sheet. Subsurface ocean warming causes basal ice-shelf melt, freshening the surface waters around Antarctica, which leads to increases in sea-ice cover. With climate warming ongoing, future mass-loss rates are projected to accelerate, which has the potential to affect future Antarctic sea-ice trends. Here we investigate to what extent future sea-ice trends are influenced by projected increases in Antarctic freshwater flux due to subsurface melt, using a state-of-the-art global climate model (EC-Earth) in standardized Climate Model Intercomparison Project phase 5 (CMIP5) climate-change simulations. Virtually all CMIP5 models disregard ocean–ice-sheet interactions and project strongly retreating Antarctic sea ice. Applying various freshwater flux scenarios, we find that the additional fresh water significantly offsets the decline in sea-ice area and is even able to reverse the trend in the strongest freshwater forcing scenario that can reasonably be expected, especially in austral winter. The model also simulates decreasing sea surface temperatures (SSTs), with the SST trends exhibiting strong regional variations that largely correspond to regional sea-ice trends.
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Cunningham, Stuart A. "Southern Ocean circulation." Archives of Natural History 32, no. 2 (October 2005): 265–80. http://dx.doi.org/10.3366/anh.2005.32.2.265.
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The Discovery Investigations of the 1930s provided a compelling description of the main elements of the Southern Ocean circulation. Over the intervening years, this has been extended to include ideas on ocean dynamics based on physical principles. In the modern description, the Southern Ocean has two main circulations that are intimately linked: a zonal (west-east) circumpolar circulation and a meridional (north-south) overturning circulation. The Antarctic Circumpolar Current transports around 140 million cubic metres per second west to east around Antarctica. This zonal circulation connects the Atlantic, Indian and Pacific Oceans, transferring and blending water masses and properties from one ocean basin to another. For the meridional circulation, a key feature is the ascent of waters from depths of around 2,000 metres north of the Antarctic Circumpolar Current to the surface south of the Current. In so doing, this circulation connects deep ocean layers directly to the atmosphere. The circumpolar zonal currents are not stable: meanders grow and separate, creating eddies and these eddies are critical to the dynamics of the Southern Ocean, linking the zonal circumpolar and meridional circulations. As a result of this connection, a global three-dimensional ocean circulation exists in which the Southern Ocean plays a central role in regulating the Earth's climate.
Dissertations / Theses on the topic "Antarctic Ocean Climate"
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Williams, Adam Peter. "Antarctic climate : ocean fluxes and variability." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/63753/.
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The Southern Ocean plays a major role in the global overturning circulation, providing an important route for the return flow of deep water subducted in the North Atlantic. The World Ocean Circulation Experiment (WOCE) provided an unprecedented picture of the state of the world’s oceans and set new standards for high quality in-situ hydrographic data. This study combines the existing WOCE data set with new hydrographic sections, and output from global and regional ocean models to examine the mean state of the Southern Ocean circulation and the balance of fluxes around the Antarctic Circumpolar current. A historical data set in the region of Drake Passage is examined to study the large-scale water mass variability between 1926-2005. The water mass properties of the Lower Circumpolar Deep Water is constant within error bounds throughout the data set. A warming and freshening signal in the surface waters from 1997-2005 to the north of the Sub-Antarctic Front along SR01b is also presented. The major part of this work is based around an inverse study of the Southern Ocean that combines the WOCE data-set with contemporary sections, and other forcing fields to examine the balance of fluxes throughout the Southern Ocean. The study examines the effect of different parameterisations of the dianeutral mixing in the Southern Ocean, in light of the differing views of localised deep turbulent mixing from observations, and an adiabatic ocean interior from residual mean studies, The freshwater balance in the model is presented and its implications on the water mass formation and transformation of the upper and lower cells of the overturning circulation is discussed in detail.
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Goddard, Paul B., Carolina O. Dufour, Jianjun Yin, Stephen M. Griffies, and Michael Winton. "CO2-Induced Ocean Warming of the Antarctic Continental Shelf in an Eddying Global Climate Model." AMER GEOPHYSICAL UNION, 2017. http://hdl.handle.net/10150/626296.
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Ocean warming near the Antarctic ice shelves has critical implications for future ice sheet mass loss and global sea level rise. A global climate model with an eddying ocean is used to quantify the mechanisms contributing to ocean warming on the Antarctic continental shelf in an idealized 2xCO(2) experiment. The results indicate that relatively large warm anomalies occur both in the upper 100 m and at depths above the shelf floor, which are controlled by different mechanisms. The near-surface ocean warming is primarily a response to enhanced onshore advective heat transport across the shelf break. The deep shelf warming is initiated by onshore intrusions of relatively warm Circumpolar Deep Water (CDW), in density classes that access the shelf, as well as the reduction of the vertical mixing of heat. CO2-induced shelf freshening influences both warming mechanisms. The shelf freshening slows vertical mixing by limiting gravitational instabilities and the upward diffusion of heat associated with CDW, resulting in the buildup of heat at depth. Meanwhile, freshening near the shelf break enhances the lateral density gradient of the Antarctic Slope Front (ASF) and disconnect isopycnals between the shelf and CDW, making cross-ASF heat exchange more difficult. However, at several locations along the ASF, the cross-ASF heat transport is less inhibited and heat can move onshore. Once onshore, lateral and vertical heat advection work to disperse the heat anomalies across the shelf region. Understanding the inhomogeneous Antarctic shelf warming will lead to better projections of future ice sheet mass loss.
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Boehme, Lars. "The frontal system of the Antarctic Circumpolar Current : marine mammals as ocean explorers." Thesis, St Andrews, 2008. http://hdl.handle.net/10023/687.
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Henley, Sian Frances. "Climate-induced changes in carbon and nitrogen cycling in the rapidly warming Antarctic coastal ocean." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/7626.
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The western Antarctic Peninsula (WAP) is a hotspot of climatic and oceanographic change, with a 6°C rise in winter atmospheric temperatures and >1°C warming of the surface ocean since the 1950s. These trends are having a profound impact on the physical environment at the WAP, with widespread glacial retreat, a 40% decline in sea ice coverage and intensification of deep water upwelling. The main objective of this study is to assess the response of phytoplankton productivity to these changes, and implications for the marine carbon and nitrogen cycles in the WAP coastal zone. An extensive suite of biogeochemical and physical oceanographic data was collected over five austral summer growing seasons in northern Marguerite Bay between 2004 and 2010. Concentrations and isotopic compositions ( 15N, 13C, 14C) of dissolved nitrate, dissolved inorganic carbon species, particulate nitrogen, organic carbon and chlorophyll a are used in the context of a substantial ancillary dataset to investigate nutrient supply, phytoplankton productivity and nutrient uptake, export flux and the fate of organic material, and the factors underpinning pronounced seasonal and interannual variability. High-resolution biogeochemical time-series data for surface and underlying seawater, sea ice brine, sediment trap material and coretop sediments allow detailed examination of carbon and nitrogen cycle processes under contrasting oceanographic conditions and the interaction between these marine processes and air-sea exchange of climate-relevant CO2. This study shows that the WAP marine environment is currently a summertime sink for atmospheric CO2 in most years due to high productivity and biological carbon uptake sufficient to offset the CO2 supply from circumpolar deep waters, which act as a persistent source of heat, nutrients and CO2 across the shelf. For the first time, CO2 sink/source behaviour is parameterised in terms of nitrate utilisation, by exploiting the relationship between CO2 and nitrate concentrations, and deriving the nitrate depletion at which surface ocean CO2 is undersaturated relative to atmosphere and carbon sink behaviour is achieved. This could have vast utility in examining CO2 sink/source dynamics over greater spatial and temporal scales than by direct CO2 measurements, of which availability is more limited. This study documents abrupt changes in phytoplankton productivity, nitrate utilisation and biological CO2 uptake during a period of rapid sea ice decline. In fact, nitrate utilisation, particulate organic matter production and biological CO2 uptake all decrease by at least 50 % between a sea ice-influenced, high productivity season and one of low sea ice and low productivity. The key driver of interannual variability in production and export of organic material is found to be upper ocean stratification and its regulation of light availability to phytoplankton. Productivity, CO2 uptake and export are maximal when stratification is sufficient to provide a stable well-lit surface environment for phytoplankton growth, but with some degree of mixing to promote export of suspended organic matter. Strong stratification causes intense initial production, but retention of suspended organic particles in the surface ocean induces a self-shading effect, and overall productivity, CO2 uptake and export fluxes are low. When stratification is weak, mixing of phytoplankton over a larger depth range exposes cells to a wider range of light levels and reduces photosynthetic efficiency, thus total productivity and CO2 uptake. A conceptual model is developed here, which attempts to describe the mechanism by which sea ice dynamics exert the principal control on stratification and therefore productivity and CO2 uptake at the WAP, with potential application to other regions of the Antarctic continental shelf. Although meteoric waters (glacial melt and precipitation) are more prevalent in surface waters throughout the study, sea ice meltwater variability is driven by large and rapid spring/early summer pulses, which stabilise the upper ocean and initiate phytoplankton growth. The timing and magnitude of these sea ice melt pulses then exert the key control on stratification and seasonal productivity. In a low sea ice year of this study, the sea ice trigger mechanism was absent and productivity was low. This strongly suggests that ongoing sea ice decline at the WAP and greater frequency of such low sea ice years is likely to drive a dramatic reduction in productivity and export, which would substantially reduce the capacity of the summertime CO2 sink in this region. Ongoing warming and ecosystem change are thus likely to have severe impacts on net CO2 sink/source behaviour at the WAP over the annual cycle, and the role of the Southern Ocean in regulating atmospheric CO2 and global climate. Finally, factors influencing the stable isotopic signature of particulate organic carbon ( 13CPOC), a common paleo-proxy, are assessed. 13CPOC is greatly influenced by seasonal shifts in diatom assemblages and isotopically heavy sea ice material, so cannot be used as a robust proxy for ambient CO2 in the coastal Southern Ocean.
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Graham, Robert M. "The role of Southern Ocean fronts in the global climate system." Doctoral thesis, Stockholms universitet, Institutionen för geologiska vetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-108736.
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The location of fronts has a direct influence on both the physical and biological processes in the Southern Ocean. However, until recently fronts have been poorly resolved by available data and climate models. In this thesis we utilise a combination of high resolution satellite data, model output and ARGO data to improve our basic understanding of fronts. A method is derived whereby fronts are identified as local maxima in sea surface height gradients. In this way fronts are defined locally as jets, rather than continuous-circumpolar water mass boundaries. A new climatology of Southern Ocean fronts is presented. This climatology reveals a new interpretation of the Subtropical Front. The currents associated with the Subtropical Front correspond to the western boundary current extensions from each basin, and we name these the Dynamical Subtropical Front. Previous studies have instead suggested that the Subtropical Front is a continuous feature across the Southern Ocean associated with the super gyre boundary. A comprehensive assessment of the relationship between front locations and wind stress is conducted. Firstly, the response of fronts to a southward shift in the westerly winds is tested using output from a 100 year climate change simulation on a high resolution coupled model. It is shown that there was no change in the location of fronts within the Antarctic Circumpolar Current as a result of a 1.3° southward shift in the westerly winds. Secondly, it is shown that the climatological position of the Subtropical Front is 5-10° north of the zero wind stress curl line, despite many studies assuming that the location of the Subtropical Front is determined by the zero wind stress curl. Finally, we show that the nutrient supply at ocean fronts is primarily due to horizontal advection and not upwelling. Nutrients from coastal regions are entrained into western boundary currents and advected into the Southern Ocean along the Dynamical Subtropical Front.At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.
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Goddard, Paul Brent, and Paul Brent Goddard. "Oceanic Controls of North American East Coast Sea Level Rise and Ocean Warming of the Antarctic Shelf." Diss., The University of Arizona, 2018. http://hdl.handle.net/10150/626684.
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Sea level rise (SLR) threatens coastal communities, infrastructure, and ecosystems. Worldwide, stakeholders critically depend on SLR projections with the associated uncertainty for risk assessments, decision-making and coastal planning. Recent research suggests that the Antarctic ice sheet mass loss during the 21st century may contribute up to an additional one meter of global SLR by year 2100. While uncertainty still exists, this value would double the ‘likely’ (> 66% probability) range of global SLR (0.52-0.98 m) by the year 2100, as found by Chapter 13 on Sea Level Change in the Fifth Assessment Report by the Intergovernmental Panel on Climate Change. Here, we present three studies that assess mechanisms relevant to 21st century local, regional, and global SLR. Appendix A examines the effect of large-scale oceanic and atmospheric circulation variability on extreme sea levels along the East Coast of North America. Appendices B and C analyze ocean warming on the Antarctic shelf and its implications for future ice shelf basal melt and Antarctic Ice Sheet mass loss. These studies will contribute to more accurate projections of local, regional, and global SLR.
In Appendix A, we analyze long-term tide gauge records from the North American eastern seaboard and find an extreme SLR event during 2009-2010. Within this two-year period, coastal sea levels spiked between Montauk, New York and Southern Canada by up to 128 mm. This two-year spike is unprecedented in the tide gauge record and found to be a 1-in-850 year event. We show that a 30% reduction in strength of the Atlantic meridional overturning circulation (AMOC) and a strong negative North Atlantic Oscillation (NAO) index caused the extreme SLR event. Climate models project that the AMOC will weaken and NAO variability will remain high over the 21st century. Consequently, extreme SLR events on the Northeast Coast could become more frequent during the 21st century in response to climate change and SLR.
In Appendix B, we use a fine-resolution global climate model (GFDL CM2.6) that resolves an eddying ocean. With this state-of-the-art coupled model, we quantify the mechanisms contributing to ocean warming on the Antarctic continental shelf in an idealized experiment of doubling of the atmospheric CO2 concentration. The results show that the CO2 forcing leads to the shelf region warming both in the upper 100 m ocean and at depths near the sea floor. These warming patterns are controlled by different mechanisms. In the upper 100 m, the heat anomalies are primarily controlled by increased heat transport into the shelf region associated with the warmer near-surface waters from lower latitudes. Below 100 m, the heat anomalies develop due to increased onshore intrusions of relatively warm Circumpolar Deep Water and reduced vertical mixing of heat in the water column. A complete heat budget analysis is performed for the Antarctic shelf region as well as for six subdomains and three depth ranges (0-100 m, 100-700 m, and 700-1000 m). The results show that certain regions of the Antarctic shelf are more susceptible to large CO2-forced warming. These findings have implications for future Antarctic Ice Sheet mass loss and SLR, and can provide more detailed and accurate ocean boundary conditions for dynamical ice sheet models.
In Appendix C, we use CM2.6 to examine the connections among ocean freshening and the magnitude and location of ocean warming on the Antarctic shelf. We find that CO2 forcing freshens the Antarctic shelf seas via increases in local precipitation, sea ice loss, liquid runoff, and iceberg calving. The freshening induces three heat budget-relevant responses: (1) reduced vertical mixing; (2) strengthening of the Antarctic Slope Front (ASF); and (3) increased eddy kinetic energy (EKE) near the ASF. First, heat can accumulate at depth (100-1000 m) as freshening increases the vertical stratification on the shelf and reduces upward mixing of heat associated with diffusion and convective processes. Second, freshening near the shelf break strengthens the ASF by increasing the lateral density gradient and by steepening and deepening the associated isopycnals. This response limits cross-ASF onshore heat transport at many locations around Antarctica. Third, EKE increases near the ASF may contribute to shelf warming by increasing cross-ASF onshore eddy heat transport. These results demonstrate the importance of shelf freshening to the development of positive heat anomalies on the Antarctic shelf. The findings provide new insight to the location of future shelf warming and ice shelf basal melting as well as provide significant information for projecting regional and global SLR.
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Suprenand, Paul Mark. "Investigations for utilizing pteropods as bioindicators of environmental change along the western Antarctic Peninsula." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4588.
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Pteropods are holoplanktonic gastropod molluscs found globally. Although species diversity is greater at lower latitudes, species abundance is greater at temperate and polar latitudes. Declines in pteropod populations have not only been correlated to declines of their major predators, but pteropods have also been used as bioindicators of global environmental changes such as ocean acidification. With high latitude abundances, pteropods provide significant sustenance for species such as the Atlantic salmon in the Atlantic Ocean and Pleuragramma antarcticum in the Southern Ocean. Because pteropods eat phytoplankton and other pteropods, factors that affect pteropod abundance influence many trophic levels. This dissertation explores ecological, physiological and trophodynamic relationships of pteropods when considering the influences of environmental factors observed to be altering the western Antarctic Peninsula's marine ecosystem. Over the last few decades very few studies have reported the distributions of pteropods along the western Antarctic Peninsula, in particular south of the Gerlache Strait. The ecological study provided the first detailed report of the pteropods Spongiobranchaea australis and Clione antarctica along the western Antarctic Peninsula south of the Gerlache Strait, and their local distribution was correlated to the region's major water masses and mesoscale water mass circulation. The physiological study of S. australis and C. antarctica yielded the first account of their metabolism, ratios of oxygen consumed to nitrogen excreted, proximate body composition, primary substrates oxidized, and enzymatic activities along the study's latitudinal gradient; the first report of S. australis' physiology anywhere around Antarctica. The final chapter utilized a comprehensive Ecopath with Ecosim model of the western Antarctic Peninsula's marine ecosystem. The model was used to explore the trophodynamic significance of pteropods within their polar marine ecosystem as well as changes in whole ecosystem trophodynamics by employing various climate change scenarios expected to alter the Peninsula's marine ecosystem over the next 40 years. The sum of these studies provides a foundation for exploring pteropods as bioindicators of environmental change along the western Antarctic Peninsula, a region currently experiencing considerable climate anomalies.
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Sleadd, Isaac Martin. "CCAAT/Enhancer-Binding Protein Delta (C/EBP-delta) Expression in Antarctic Fishes: Implications for Cell Cycle and Apoptosis." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/994.
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Chapter 1: Antarctic fishes are extremely cold adapted. Despite their inability to upregulate heat shock proteins, recent studies have demonstrated a capacity for heat response in these animals. A cDNA microarray study looked at the Notothenioid fish Trematomus bernacchii and revealed heat sensitivities for hundreds of genes, two of which code for members of the CCAAT/Enhancer-binding protein (C/EBP) family of transcription factors. These molecular switches are best known for their roles in apoptosis, inflammation and cell cycle arrest. This dissertation further elucidates the role of C/EBP-delta in the Antarctic fishes T. bernacchii and Pagothenia borchgrevinki.
Chapter 2: C/EBP-delta is constitutively expressed in unstressed, field-acclimated (ca. -1.86°C) animals in a highly tissue-specific manner. White muscle tissue contains the highest C/EBP-delta concentration, which is further increased in response to sublethal heat stress at 2.0 or 4.0°C. This response is mostly acute and transitory, but a lesser upregulation was observed in fishes held for one month at 4.0°C.
Chapter 3: The heat-induced nuclear translocation of C/EBP-delta--as determined by immunohistochemistry--appears to be time, tissue and species specific with spleen, heart and retinae being particularly responsive in certain situations.
Chapter 4: Protein concentrations of proliferating cell nuclear antigen are tissue specific and variably heat responsive. Surprisingly, levels appear to be positively correlated with C/EBP-delta.
Chapter 5: Flow cytometry revealed increasingly high temperatures reduce the proportion of G1 cells while increasing the abundance of apoptotic cells.
Chapter 6: These findings are discussed in the context of global climate change and the cellular stress response.
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Donat-Magnin, Marion. "Variabilité atmosphérique en Antarctique de l'Ouest : Impact sur la circulation océanique et sur le bilan de masse de surface de la calotte Interannual Variability of Summer Surface Mass Balance and Surface Melting in the Amundsen Sector, West Antarctica." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU032.
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Depuis les années 90, l’Antarctique de l’Ouest, dont le secteur d’Amundsen, affiche une importante perte de masse provenant principalement de l’accélération des glaciers côtiers en réponse à une fonte océanique plus conséquente sous les plateformes de glace. Ces plateformes sont généralement confinées est agissent comme un verrou pour l’écoulement. En subissant davantage de fonte basale, les plateformes deviennent fragiles et les glaciers en amont s’accélèrent, contribuant ainsi à augmenter le niveau des mers. L’avenir de l’Antarctique de l’Ouest est particulièrement préoccupant car sa configuration rend la calotte sujette à une instabilité marine. Par ailleurs, ces plateformes pourraient s’affaiblir sous l’effet d’une augmentation de la fonte de surface dans un climat plus chaud (hydrofracturation), rendant là aussi une instabilité possible. L’arrivée de ces instabilités pourrait être freinée ou compensée par l’évolution du bilan de masse de surface qui se compose majoritairement de précipitations neigeuses, sporadiquement augmenté par la pluie, et légèrement amoindri par la sublimation et le runoff. Cette thèse porte sur la modélisation de l’ensemble des processus atmosphériques et océaniques pouvant faire évoluer la contribution de l’Antarctique de l’Ouest au niveau des mers.Pour cela une projection océanique représentant les cavités sous-glaciaires a d’abord été réalisée avec le modèle NEMO. La circulation induite par la fonte océanique modifie la réponse de l’océan côtier à un futur changement de circulation atmosphérique, si bien qu’utiliser des modèles de climat ne représentant pas les cavités donne une indication faussée du réchauffement de l’océan autour de la calotte. Nous avons également mis en évidence une rétroaction positive entre la fonte sous-glaciaire et le retrait de la ligne d’échouage, entraînant une augmentation de la fonte jusqu’à 2.5 fois. Ces résultats indiquent la nécessité de coupler des modèles de calotte et d’océan pour établir des projections futures, même si les projections envisagées dans cette thèse restent relativement idéalisées.Pour établir des projections de bilan de masse de surface, il est nécessaire d’utiliser un modèle atmosphérique avec une représentation fine des processus polaires, notamment ceux liés au manteau neigeux. Ainsi nous avons utilisé le modèle atmosphérique régional MAR pour établir des projections dans le secteur d’Amundsen. Nous avons d’abord montré que MAR est approprié pour représenter le climat de surface observé en Antarctique de l’Ouest. Nous avons trouvé qu’aucun des modes climatiques (ASL, SAM, ENSO) n’expliquent plus de 50% de la variance de la fonte et du SMB en été à l’échelle interannuelle, et il est donc difficile d’utiliser des projections des modes climatiques comme indication de l’évolution du climat de surface.Forcé par le signal multi-modèle CMIP5 dans le scénario rcp85, MAR prévoit une augmentation du bilan de masse de surface de 30-40% d’ici 2100. Cette augmentation est équivalente à une baisse de 0.33 mm/an de niveau des mers, ce qui compenserait l’effet de la dynamique si celle-ci restait à son niveau actuel (0.26 mm/an). Ces projections indiquent également 5 à 15 fois plus de fonte de surface sur les plateformes du secteur Amundsen, mais la quasi-totalité de la fonte produite chaque année continue à regeler dans la couche de neige annuelle, et ne devrait donc contribuer de manière importante ni au bilan de masse de surface ni à l’hydrofracturation.Il ressort de ces travaux qu’un couplage océan/calotte dans les modèles de climat est primordial pour simuler le futur de l’Antarctique et de l’océan Austral. Une représentation fine des processus liés à la fonte de surface et au regel dans le névé est également essentielle car la possibilité d’hydrofracturation des plateformes dans un climat plus chaud relève d’un équilibre subtil entre l’augmentation de l’accumulation, de la température, et les rétroactions liées à l’albédo et à l’humiditéWest Antarctica, and particularly the Amundsen sector, has shown since the 1990s a large increase of mass loss related to coastal glacier acceleration in response to an increase of oceanic melt underneath ice shelves. Ice shelves play a buttressing role for ice-stream and increased oceanic melt therefore lead to ice shelves thinning and glacier acceleration, which contributes to sea level rise. West Antarctica is of particular concern because its configuration is prone to marine ice-sheet instability. It has been suggested that ice shelves weaken under large surface melt in a warmer climate (hydrofracturing), possibly leading to another kind of instability. Instabilities could be slowed down or compensated by future Surface Mass Balance (SMB) that consists mainly of snowfall, sporadic rainfall, and is slightly reduced by sublimation and runoff. The main objective of this PhD work is to model the atmospheric and oceanic processes that will most likely affect the future West Antarctic contribution to sea level rise.First, oceanic projections have been developed using the NEMO ocean model. The ocean circulation induced by ice-shelf basal melting affects the ocean response to future changes in surface winds. Therefore, models that do not represent ice-shelf cavities produce wrong warming patterns around Antarctica. A positive feedback between oceanic melting and grounding-line retreat has been identified and can increase melt rates by a factor of 2.5. These results are strong incentive to couple ocean and ice sheet models, although the projections proposed here are relatively idealized.To run SMB and surface melting projections, an atmospheric model with a fine representation of polar processes, including those related to the snowpack, is needed. MAR is found to be an appropriate tool to simulate the present-day surface climate in the Amundsen region. We find that none of the large climate modes of variability (ASL, SAM, ENSO) explains more than 50% of surface melt and SMB summer variance at the interannual timescale. The use of climate mode variability projections to estimate the future surface climate of West Antarctica is therefore not trivial.Forced by the CMIP5 multi-model mean under the RCP8.5 scenario, MAR predicts an increase of SMB by 30-40% for the end of the 21st century. This increase corresponds to 0.33 mm yr-1 of sea level drop down, which is higher than the current West Antarctic contribution of ~0.26 mm yr-1 from ice dynamics. Surface melt is also projected to increase by a factor of 5 to 15 over the Amundsen ice shelves, but most of it is projected to refreeze in the annual snow layer, so future melting should not have a strong contribution to SMB or hydrofracturing.To conclude we show that coupled ocean and ice sheet climate models are essential to simulate the future of Antarctica and Southern Ocean. A fine representation of surface melt and refreezing processes within the snowpack is also crucial as possible hydrofracturing is threatening in a warmer climate and it comes within a delicate equilibrium between snowfall, air temperature, and feedback related to albedo and humidity
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Gregory, Thomas R. "Holocene sea ice-ocean-climate variability from Adélie Land, East Antarctica." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/41566/.
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Marine sedimentation from the Adélie Land continental margin of East Antarctica provides unique high resolution records of Holocene environmental change. The subannually resolved sediment cores MD03-2601 (66°03.07’S, 138°33.43’E) and IODP-318-U1357B (66°24.7990′S, 140°25.5705′E) from the Dumont d’Urville Trough,Adélie Land, document atmospheric and oceanic processes impacting on biogenic sedimentation on the Adélie Land continental shelf during the Holocene. Resin embedded, continuous polished thin sections from each core were analysed for diatom content and sediment microfabric using scanning electron microscope backscattered electron imagery. The sediments contained repeating sequences of seasonal diatom-rich laminae which enabled multi-taper method time series analysis. Time series analysis shows that in the Hypsithermal there appears to have been an external (solar) control on interannual sedimentation as well as internal controls (e.g. the southern annular mode, SAM, and El Nino-southern Oscillation, ENSO); whilst in the Neoglacial internal climatic modes exerted a much stronger control. Quasi-biennial (2 – 3 year) peaks commonly occurred in analysis of both Hypsitherml and Neoglacial sequences. The distribution of resting spore-rich laminae in these sections suggests that a multidecadal (>50-years) variation between phasing of the SAM and ENSO systems may exert an important control on interannual environmental variability in the sections analysed. The distribution of diatom-derived biomarker proxies, namely C25 highly branched isoprenoid (HBI) alkenes, was compared to the diatom lamina-based record in core MD03-2601. At the Holocene scale, HBI diene and triene molecules have a positive association to sea ice associated diatom-rich laminae, with greater abundances of both HBI molecules and sea ice associated diatom laminae in the Neoglacial interval. However, at a sub-annual resolution there is no strong association between lamina type and HBI concentrations. This is attributed to a combination of: (i) the HBI alkenes recording a different signal to that of the diatom-rich laminae; (ii) interannual variation in HBI export that is greater than inter-seasonal variation, for which there is little modern data for comparison; (iii) possible diagenetic alteration of the HBI signal.
Books on the topic "Antarctic Ocean Climate"
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Macalady, Alison, and Katie Thomas, eds. Antarctic Sea Ice Variability in the Southern Ocean-Climate System. Washington, D.C.: National Academies Press, 2017. http://dx.doi.org/10.17226/24696.
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Singh, Jaswant, Jaswant Singh, and H. N. Dutta. Antarctica: The most interactive ice-air-ocean environment. Hauppage, N.Y: Nova Science Publishers, 2011.
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(US), National Research Council. Future science opportunities in Antarctica and the southern ocean. Washington, D.C: National Academies Press, 2011.
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Antarctica: The most interactive ice-air-ocean environment. Hauppage, N.Y: Nova Science Publishers, 2011.
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Exon, Neville F., James P. Kennett, and Mitchell J. Malone, eds. The Cenozoic Southern Ocean: Tectonics, Sedimentation, and Climate Change Between Australia and Antarctica. Washington, D. C.: American Geophysical Union, 2004. http://dx.doi.org/10.1029/gm151.
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Morozov, Eugene G. Abyssal Channels in the Atlantic Ocean: Water Structure and Flows. Dordrecht: Springer Science+Business Media B.V., 2010.
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1861-1930, Nansen Fridtjof, Johannessen Ola M, Muench Robin D, Overland James E, and Nansen Centennial Symposium (1993 : Solstrand, Norway), eds. The polar oceans and their role in shaping the global environment: The Nansen centennial volume. Washington, DC, USA: American Geophysical Union, 1994.
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Lurcock, Pontus, and Fabio Florindo. Antarctic Climate History and Global Climate Changes. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780190676889.013.18.
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Antarctic climate changes have been reconstructed from ice and sediment cores and numerical models (which also predict future changes). Major ice sheets first appeared 34 million years ago (Ma) and fluctuated throughout the Oligocene, with an overall cooling trend. Ice volume more than doubled at the Oligocene-Miocene boundary. Fluctuating Miocene temperatures peaked at 17–14 Ma, followed by dramatic cooling. Cooling continued through the Pliocene and Pleistocene, with another major glacial expansion at 3–2 Ma. Several interacting drivers control Antarctic climate. On timescales of 10,000–100,000 years, insolation varies with orbital cycles, causing periodic climate variations. Opening of Southern Ocean gateways produced a circumpolar current that thermally isolated Antarctica. Declining atmospheric CO2 triggered Cenozoic glaciation. Antarctic glaciations affect global climate by lowering sea level, intensifying atmospheric circulation, and increasing planetary albedo. Ice sheets interact with ocean water, forming water masses that play a key role in global ocean circulation.
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Lurcock, Pontus, and Fabio Florindo. Antarctic Climate History and Global Climate Changes. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780190699420.013.18.
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Antarctic climate changes have been reconstructed from ice and sediment cores and numerical models (which also predict future changes). Major ice sheets first appeared 34 million years ago (Ma) and fluctuated throughout the Oligocene, with an overall cooling trend. Ice volume more than doubled at the Oligocene-Miocene boundary. Fluctuating Miocene temperatures peaked at 17–14 Ma, followed by dramatic cooling. Cooling continued through the Pliocene and Pleistocene, with another major glacial expansion at 3–2 Ma. Several interacting drivers control Antarctic climate. On timescales of 10,000–100,000 years, insolation varies with orbital cycles, causing periodic climate variations. Opening of Southern Ocean gateways produced a circumpolar current that thermally isolated Antarctica. Declining atmospheric CO2 triggered Cenozoic glaciation. Antarctic glaciations affect global climate by lowering sea level, intensifying atmospheric circulation, and increasing planetary albedo. Ice sheets interact with ocean water, forming water masses that play a key role in global ocean circulation.
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National Academies of Sciences, Engineering, and Medicine. Antarctic Sea Ice Variability in the Southern Ocean-Climate System: Proceedings of a Workshop. National Academies Press, 2017.
Find full textBook chapters on the topic "Antarctic Ocean Climate"
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Tréguer, Paul. "The Southern Ocean: Biogeochemical Cycles and Climate Changes." In Antarctic Science, 110–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-78711-9_9.
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KAPSENBERG, LYDIA, AMANDA L. KELLEY, EMILY C. SHAW, TODD R. MARTZ, and GRETCHEN E. HOFMANN. "chapter 11 Near-Shore Antarctic pH Variability has Implications for the Design of Ocean Acidification Experiments." In Climate Change and the Oceanic Carbon Cycle, 239–66. 3333 Mistwell Crescent, Oakville, ON L6L 0A2, Canada: Apple Academic Press, 2017. http://dx.doi.org/10.1201/9781315207490-12.
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Shevenell, A. E., and J. P. Kennett. "Paleoceanographic change during the Middle Miocene climate revolution: An Antarctic stable isotope perspective." In The Cenozoic Southern Ocean: Tectonics, Sedimentation, and Climate Change Between Australia and Antarctica, 235–51. Washington, D. C.: American Geophysical Union, 2004. http://dx.doi.org/10.1029/151gm14.
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Choudhary, Shabnam, and Neloy Khare. "Climate Change Over the Antarctic and the Southern Ocean and Its Impact and Bearing on the Global Climate System." In Earth and Environmental Sciences Library, 37–46. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-87078-2_3.
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Sonbawne, S. M., P. C. S. Devara, P. R. C. Rahul, and K. K. Dani. "Transient Variations in En Route Southern Indian Ocean Aerosols, Antarctic Ozone Climate, and Its Relationship with HOx and NOx." In Climate Variability of Southern High Latitude Regions, 115–35. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003203742-5.
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Exon, Neville F., Henk Brinkhuis, Christian M. Robert, James P. Kennett, Peter J. Hill, and Michael K. Macphail. "Tectono-sedimentary history of uppermost Cretaceous through Oligocene sequences from the Tasmanian region: A temperate Antarctic margin." In The Cenozoic Southern Ocean: Tectonics, Sedimentation, and Climate Change Between Australia and Antarctica, 319–44. Washington, D. C.: American Geophysical Union, 2004. http://dx.doi.org/10.1029/151gm18.
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White, Timothy S. "A chemostratigraphic and geochemical facies analysis of strata deposited in an Eocene Australo-Antarctic Seaway: Is cyclicity evidence for glacioeustasy?" In The Cenozoic Southern Ocean: Tectonics, Sedimentation, and Climate Change Between Australia and Antarctica, 153–72. Washington, D. C.: American Geophysical Union, 2004. http://dx.doi.org/10.1029/151gm10.
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Wylie, D. J., M. J. Harvey, S. J. de Mora, I. S. Boyd, and J. B. Liley. "Dimethylsulfide and Aerosol Measurements at Ross Island, Antarctica." In Dimethylsulphide: Oceans, Atmosphere and Climate, 85–94. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-1261-3_10.
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Staubes, Regina, and Hans-Walter Georgii. "Measurements of Atmospheric and Seawater DMS Concentrations in the Atlantic, the Arctic and Antarctic Region." In Dimethylsulphide: Oceans, Atmosphere and Climate, 95–102. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-1261-3_11.
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McTaggart, A., and H. Burton. "Aspects of the Biogeochemistry of Dimethylsulfide (DMS) and Dimethylsulfoniumpropionate (DMSP) at an Antarctic Coastal Site." In Dimethylsulphide: Oceans, Atmosphere and Climate, 43–52. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-017-1261-3_6.
Full textConference papers on the topic "Antarctic Ocean Climate"
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Marynets, K. "Study of the Antarctic Circumpolar Current via the Shallow Water Large Scale Modelling." In Floating Offshore Energy Devices. Materials Research Forum LLC, 2022. http://dx.doi.org/10.21741/9781644901731-11.
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Abstract. This paper proposes a modelling of the Antarctic Circumpolar Current (ACC) by means of a two-point boundary value problem. As the major means of exchange of water between the great ocean basins (Atlantic, Pacific and Indian), the ACC plays a highly important role in the global climate. Despite its importance, it remains one of the most poorly understood components of global ocean circulation. We present some recent results on the existence and uniqueness of solutions of a two-point nonlinear boundary value problem that arises in the modeling of the flow of the (ACC) (see discussions in [4-9]).
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Williams, Thomas J., Ellen E. Martin, Elisabeth Sikes, and Aidan Starr. "NEODYMIUM ISOTOPE EVIDENCE FOR COUPLED SOUTHERN OCEAN CIRCULATION AND ANTARCTIC CLIMATE THROUGHOUT THE LAST 120,000 YEARS." In Joint 69th Annual Southeastern / 55th Annual Northeastern GSA Section Meeting - 2020. Geological Society of America, 2020. http://dx.doi.org/10.1130/abs/2020se-345035.
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Palmer, Andrew, David Keith, and Richard Doctor. "Ocean Storage of Carbon Dioxide: Pipelines, Risers and Seabed Containment." In ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2007. http://dx.doi.org/10.1115/omae2007-29529.
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Eight hundred tonnes of carbon dioxide (CO2) are dumped into the atmosphere every second. There has been a progressive rise in the CO2 content of the atmosphere, from 270 ppm in the pre-industrial era to more than 380 ppm now, rising by 15 ppm/decade. The overwhelming scientific consensus is that this is having a large effect on climate, and that as a result the Earth’s temperature will rise by 2°C or more before 2100 [1]. Agriculture, forestry, fisheries, the biosphere and human health will all be affected, though not all the impacts are negative. The level of the sea will rise by between 0.5 and 1 m, and there is a possibility of a much greater and catastrophic rise if warming should lead to a collapse of the Greenland or Antarctic ice sheets.
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Panchi, Nabil, Uttam Verma, Ekaterina Kim, Nick Hughes, and Anirban Bhattacharyya. "Assessment of Uncertainty in Sea Ice Charts and Its Impact on Operational Planning in the Kara Sea Region." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-79051.
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Abstract Ice charts play an important role in the planning of marine operations, including navigational guidance among other use cases (e.g., climate monitoring and model validation). With a growing number of vessels operating in dynamic sea ice cover and considering the November 2021 events when several ships were stuck and delayed in the Arctic waters, it becomes ever more important to have accurate and timely ice information as well as to account for the underlying uncertainties in the sea ice products. To this end, the present study evaluates the variability in estimated total sea ice concentration in ice charts of the Russian Arctic and Antarctic Research Institute (AARI) and the Norwegian Meteorological Institute (MET Norway). The weekly ice charts from AARI were compared with several daily charts from MET Norway for the corresponding week to discover any discrepancies in the reported sea ice concentration. Preliminary results of this study indicate seasonal as well as spatial trends in the absolute difference in total ice concentration between the two sea ice products. A higher difference in concentrations was observed in the western and the central regions of the Kara Sea which see a lot of ship traffic. Sensitivity of the results to the comparison approach is conducted and the found discrepancies between the two ice products are placed in the context of operational route planning.
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Kim, YoungSeok, Kiju Kim, Seung-Seo Hong, and Wanjei Cho. "The Variation of Physical Properties in Frozen Soils at Various Freezing Temperatures." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23113.
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Due to the recent climate change, the colder and longer winter is expected in Korea. Besides, the recent participation agreement on the development of the natural gas pipeline in Russia and construction of the second Korean Antarctic research station, the Jangbogo station changes the research interests from the seasonally frozen ground to the permafrost ground. The recent development of the site investigation techniques using wave propagation and electrical resistivity enabled engineers to evaluate the physical properties of the frozen soils and further correlate them to the mechanical properties. However, the physical properties of the frozen ground change when the water in the soil solidifies to ice; this change is particularly notable between 0 and −10°C. Therefore, the physical property changes due to freezing needs to be investigated in terms of wave propagation characteristics and electrical resistivity with regard to the various freezing temperatures. In this study, the characteristics of wave propagation and electrical resistivity of frozen soils are investigated under various sub-zero temperatures. The characteristics of wave propagations are analyzed in terms of compression and shear wave velocities. The electrical resistivity is measured under various sub-zero temperatures to understand the effects of ice, which will further provide the valuable information about the location of the active layer. Furthermore, the evaluated physical properties can be used as basic data for the evaluation of the mechanical properties such as strength and stiffness.
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Campos, Ricardo Martins, Andressa D’Agostini, Leandro Machado Cruz, Bruna Reis Leite França, and C. Guedes Soares. "Extreme Wind and Wave Predictability From Operational Forecasts at the Drake Passage." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-96626.
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Abstract The Drake Passage is an ocean area between the South America and Antarctic with very extreme wind and wave climates. The forecast accuracy of surface winds and significant wave heights is analyzed in the present paper, in order to study the behavior and distribution of model uncertainties as a function of: forecast range, severity, location, and numerical model. The operational forecast considered is run twice a day by the Brazilian Navy, and a period of one year (2017) is selected for the assessment. Observations consist of four satellite missions: JASON2, JASON3, CRYOSAT, and SARAL. The numerical atmospheric models with 10-m winds are GFS (Global Forecast System) and ICON (Icosahedral Nonhydrostatic Model). They force wave simulations using the model WAVEWATCH III with a mosaic of two grids. The forecast horizon analyzed is five days, which is made publicly available by the Brazilian Navy. Results show that under calm to moderate conditions, within the first two days of forecast, the wind and wave model skill is very high. However, above the 90th percentile and beyond the third forecast day, the predictability drops significantly. It highlights specific contours of forecast range versus percentiles where the wind and wave modelers should focus, in order to anticipate and to improve the predictability of extreme events at the Drake Passage.
Reports on the topic "Antarctic Ocean Climate"
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Cenedese, Claudia, and Mary-Louise Timmermans. 2017 program of studies: ice-ocean interactions. Woods Hole Oceanographic Institution, November 2018. http://dx.doi.org/10.1575/1912/27807.
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The 2017 Geophysical Fluid Dynamics Summer Study Program theme was Ice-Ocean Interactions. Three principal lecturers, Andrew Fowler (Oxford), Adrian Jenkins (British Antarctic Survey) and Fiamma Straneo (WHOI/Scripps Institution of Oceanography) were our expert guides for the first two weeks. Their captivating lectures covered topics ranging from the theoretical underpinnings of ice-sheet dynamics, to models and observations of ice-ocean interactions and high-latitude ocean circulation, to the role of the cryosphere in climate change. These icy topics did not end after the first two weeks. Several of the Fellows' projects related to ice-ocean dynamics and thermodynamics, and many visitors gave talks on these themes.