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1
Yen, Kuo-Wei, and Chia-Hsiang Chen. "Research Gap Analysis of Remote Sensing Application in Fisheries: Prospects for Achieving the Sustainable Development Goals." Remote Sensing 13, no. 5 (2021): 1013. http://dx.doi.org/10.3390/rs13051013.
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Remote sensing (RS) technology, which can facilitate the sustainable management and development of fisheries, is easily accessible and exhibits high performance. It only requires the collection of sufficient information, establishment of databases and input of human and capital resources for analysis. However, many countries are unable to effectively ensure the sustainable development of marine fisheries due to technological limitations. The main challenge is the gap in the conditions for sustainable development between developed and developing countries. Therefore, this study applied the Web of Science database and geographic information systems to analyze the gaps in fisheries science in various countries over the past 10 years. Most studies have been conducted in the offshore marine areas of the northeastern United States of America. In addition, all research hotspots were located in the Northern Hemisphere, indicating a lack of relevant studies from the Southern Hemisphere. This study also found that research hotspots of satellite RS applications in fisheries were mainly conducted in (1) the northeastern sea area in the United States, (2) the high seas area of the North Atlantic Ocean, (3) the surrounding sea areas of France, Spain and Portugal, (4) the surrounding areas of the Indian Ocean and (5) the East China Sea, Yellow Sea and Bohai Bay sea areas to the north of Taiwan. A comparison of publications examining the three major oceans indicated that the Atlantic Ocean was the most extensively studied in terms of RS applications in fisheries, followed by the Indian Ocean, while the Pacific Ocean was less studied than the aforementioned two regions. In addition, all research hotspots were located in the Northern Hemisphere, indicating a lack of relevant studies from the Southern Hemisphere. The Atlantic Ocean and the Indian Ocean have been the subjects of many local in-depth studies; in the Pacific Ocean, the coastal areas have been abundantly investigated, while offshore local areas have only been sporadically addressed. Collaboration and partnership constitute an efficient approach for transferring skills and technology across countries. For the achievement of the sustainable development goals (SDGs) by 2030, research networks can be expanded to mitigate the research gaps and improve the sustainability of marine fisheries resources.
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Jiménez, Sebastián, Andrés Domingo, Alejandro Brazeiro, et al. "Sexual size dimorphism, spatial segregation and sex-biased bycatch of southern and northern royal albatrosses in pelagic longline fisheries." Antarctic Science 29, no. 2 (2016): 147–54. http://dx.doi.org/10.1017/s0954102016000493.
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AbstractBycatch in longline fisheries is a major contributor to the global decline of albatrosses. Sexual segregation at sea often leads to unequal overlap with different fisheries, resulting in sex-biased bycatch, exacerbating the impact on a population level. In great albatrosses (Diomedea spp.), males (the larger sex) tend to spend more time at higher latitudes than females, attributed to competitive exclusion or differences in flight performance mediated by the pronounced sexual size dimorphism (SSD). Consequently, larger numbers of females are bycaught in pelagic longline fisheries in subtropical and temperate areas. Although this has been shown for Diomedea exulans, it has not been confirmed for all great albatross species. Here we examined the degree of SSD and developed discriminant functions to determine species and sex in D. epomophora and D. sanfordi; species that are often killed in several fisheries in the Southern Hemisphere. Based on a large sample of albatrosses bycaught off Uruguay, both species showed substantial SSD. Discriminant functions assigned species and sex to otherwise indeterminate individuals with 90–100% accuracy. Based on all birds identified (n=128), bycatch in the pelagic longline fishery was female-biased, indicating sexual segregation at sea. The discriminant functions presented enable species and sex to be identified, providing critical data for future bycatch assessments.
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Lehodey, P., J. Alheit, M. Barange, et al. "Climate Variability, Fish, and Fisheries." Journal of Climate 19, no. 20 (2006): 5009–30. http://dx.doi.org/10.1175/jcli3898.1.
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Abstract Fish population variability and fisheries activities are closely linked to weather and climate dynamics. While weather at sea directly affects fishing, environmental variability determines the distribution, migration, and abundance of fish. Fishery science grew up during the last century by integrating knowledge from oceanography, fish biology, marine ecology, and fish population dynamics, largely focused on the great Northern Hemisphere fisheries. During this period, understanding and explaining interannual fish recruitment variability became a major focus for fisheries oceanographers. Yet, the close link between climate and fisheries is best illustrated by the effect of “unexpected” events—that is, nonseasonal, and sometimes catastrophic—on fish exploitation, such as those associated with the El Niño–Southern Oscillation (ENSO). The observation that fish populations fluctuate at decadal time scales and show patterns of synchrony while being geographically separated drew attention to oceanographic processes driven by low-frequency signals, as reflected by indices tracking large-scale climate patterns such as the Pacific decadal oscillation (PDO) and the North Atlantic Oscillation (NAO). This low-frequency variability was first observed in catch fluctuations of small pelagic fish (anchovies and sardines), but similar effects soon emerged for larger fish such as salmon, various groundfish species, and some tuna species. Today, the availability of long time series of observations combined with major scientific advances in sampling and modeling the oceans’ ecosystems allows fisheries science to investigate processes generating variability in abundance, distribution, and dynamics of fish species at daily, decadal, and even centennial scales. These studies are central to the research program of Global Ocean Ecosystems Dynamics (GLOBEC). This review presents examples of relationships between climate variability and fisheries at these different time scales for species covering various marine ecosystems ranging from equatorial to subarctic regions. Some of the known mechanisms linking climate variability and exploited fish populations are described, as well as some leading hypotheses, and their implications for their management and for the modeling of their dynamics. It is concluded with recommendations for collaborative work between climatologists, oceanographers, and fisheries scientists to resolve some of the outstanding problems in the development of sustainable fisheries.
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Meynecke, Jan-Olaf, Mark Grubert, and Jonathan Gillson. "Giant mud crab (Scylla serrata) catches and climate drivers in Australia - a large scale comparison." Marine and Freshwater Research 63, no. 1 (2012): 84. http://dx.doi.org/10.1071/mf11149.
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Patterns in the Southern Oscillation Index (SOI) affect the life history of many aquatic organisms in the southern hemisphere. We examined the effect of this phenomenon and other factors (i.e. rainfall, river flow and sea surface temperature, SST) on the commercial harvest of the giant mud crab (Scylla serrata) in Australia, given the large inter-annual variations in the catch of this species over the last 15 years, particularly in the north. Regression models were applied to concurrent environmental and catch data for giant mud crab caught from 29 catchments that provided a combined harvest of >20 000 tonnes. Non-metric multidimensional scaling (nMDS) was also used to explore potential regional differences in catch trends. A combination of SOI, SST and rainfall/river flow explained 30–70% of the variability in commercial catches, with mean summer temperature being most influential at higher latitudes. The nMDS revealed distinct groupings of river systems that coincided with biogeographic regions. This work highlights the importance of climatic events on the harvest of giant mud crabs and reinforces the need to adopt a bioregional approach when assessing the performance of fisheries targeting this species.
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Wakefield, Corey B., Stephen J. Newman, and Brett W. Molony. "Age-based demography and reproduction of hapuku, Polyprion oxygeneios, from the south coast of Western Australia: implications for management." ICES Journal of Marine Science 67, no. 6 (2010): 1164–74. http://dx.doi.org/10.1093/icesjms/fsq021.
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Abstract Wakefield, C. B., Newman, S. J., and Molony, B. W. 2010. Age-based demography and reproduction of hapuku, Polyprion oxygeneios, from the south coast of Western Australia: implications for management. – ICES Journal of Marine Science, 67: 1164–1174. The hapuku, Polyprion oxygeneios, inhabits deep (>100 m) continental slope waters of Western Australia. In all, 1352 P. oxygeneios were collected from the waters along the south coast of Western Australia (ca. 35°S) from 2004 to 2008. The species is gonochoristic, and spawns during the austral winter (May–September). Ages were estimated from counts of opaque zones from thin-sectioned sagittal otoliths. Classification analysis of the outer margin of sectioned otoliths indicated that a single opaque zone is deposited annually. Female P. oxygeneios (n = 630; 535–1114 mm total length, TL) ranged in age from 2 to 35 years and males (n = 691; 521–1004 mm TL) from 2 to 52 years. von Bertalanffy growth models for male and female P. oxygeneios were statistically, but not biologically, different (<5% difference in mean and estimated lengths-at-age). Estimates of the lengths and ages at which 50% of the females and males in the population reached sexual maturity were 760 and 702 mm TL and 7.1 and 6.8 years. The instantaneous rate of natural mortality (M) was estimated to be 0.09. Estimates of the instantaneous rate of fishing mortality (F) were low (0.01–0.05). Harvest rates in 2005 and 2006 were close to estimated sustainable levels. Monitoring of any future increases in catch and effort in continental slope waters in both State- and Commonwealth-managed fisheries is required in order to assess impacts to stock sustainability. Sustainable management would also benefit from improved understanding of possible pan-oceanic recruitment of the species among southern hemisphere populations.
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Cheon, Woo Geun, Chang-Bong Cho, Arnold L. Gordon, Young Ho Kim, and Young-Gyu Park. "The Role of Oscillating Southern Hemisphere Westerly Winds: Southern Ocean Coastal and Open-Ocean Polynyas." Journal of Climate 31, no. 3 (2018): 1053–73. http://dx.doi.org/10.1175/jcli-d-17-0237.1.
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Abstract An oscillation in intensity of the Southern Hemisphere westerly winds is a major characteristic of the southern annular mode. Its impact upon the sea ice–ocean interactions in the Weddell and Ross Seas is investigated by a sea ice–ocean general circulation model coupled to an energy balance model for three temporal scales and two amplitudes of intensity. It is found that the oscillating wind forcing over the Southern Ocean plays a significant role both in regulating coastal polynyas along the Antarctic margins and in triggering open-ocean polynyas. The formation of coastal polynya in the western Weddell and Ross Seas is enhanced with the intensifying winds, resulting in an increase in the salt flux into the ocean via sea ice formation. Under intensifying winds, an instantaneous spinup within the Weddell and Ross Sea cyclonic gyres causes the warm deep water to upwell, triggering open-ocean polynyas with accompanying deep ocean convection. In contrast to coastal polynyas, open-ocean polynyas in the Weddell and Ross Seas respond differently to the wind forcing and are dependent on its period. That is, the Weddell Sea open-ocean polynya occurs earlier and more frequently than the Ross Sea open-ocean polynya and, more importantly, does not occur when the period of oscillation is sufficiently short. The strong stratification of the Ross Sea and the contraction of the Ross gyre due to the southward shift of Antarctic Circumpolar Current fronts provide unfavorable conditions for the Ross Sea open-ocean polynya. The recovery time of deep ocean heat controls the occurrence frequency of the Weddell Sea open-ocean polynya.
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Bruce, AJ. "Thaumastochelopsis wardi, gen. et. sp. nov., a new blind deep-sea lobster from the coral sea (Crustacea : Decapoda : Nephropidea)." Invertebrate Systematics 2, no. 7 (1988): 903. http://dx.doi.org/10.1071/it9880903.
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The nephropid lobster family Thaumastochelidae has so far only been recorded from the Northern Hemisphere in the central Atlantic Ocean and in Japanese waters, where two species of Thaumastocheles, the only genus of the family, are known. The discovery of a new genus and species in the Coral Sea is the first occurrence in the Southern Hemisphere and provides additional knowledge of this littleknown family. A modification of the diagnosis of the family is made to include the new genus, which has reduced but mobile eyes instead of obsolete fused eyestalks as in Thaumastocheles. The new lobster, Thaumastochelopsis wardi, gen. et sp. nov., was obtained from a depth of 452 m.
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Rhein, Monika, Dagmar Kieke, and Reiner Steinfeldt. "Advection of North Atlantic Deep Water from the Labrador Sea to the southern hemisphere." Journal of Geophysical Research: Oceans 120, no. 4 (2015): 2471–87. http://dx.doi.org/10.1002/2014jc010605.
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Stott, L., A. Timmermann, and R. Thunell. "Southern Hemisphere and Deep-Sea Warming Led Deglacial Atmospheric CO2 Rise and Tropical Warming." Science 318, no. 5849 (2007): 435–38. http://dx.doi.org/10.1126/science.1143791.
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Cheon, Woo Geun, and Jong-Seong Kug. "The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation." Journal of Climate 33, no. 6 (2020): 2111–30. http://dx.doi.org/10.1175/jcli-d-19-0364.1.
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AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.
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Klinger, Barry A., and Carlos Cruz. "Decadal Response of Global Circulation to Southern Ocean Zonal Wind Stress Perturbation." Journal of Physical Oceanography 39, no. 8 (2009): 1888–904. http://dx.doi.org/10.1175/2009jpo4070.1.
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Abstract A substantial component of North Atlantic Deep Water formation may be driven by westerly wind stress over the Southern Ocean. Variability of this wind stress on decadal time scales may lead to circulation variability far from the forcing region. The Hybrid Coordinate Ocean Model (HYCOM), a numerical ocean model, is used to investigate the spatial patterns and the time scales associated with such wind variability. The evolution of circulation and density anomalies is observed by comparing one 80-yr simulation, forced in part by relatively strong Southern Hemisphere westerlies, with a simulation driven by climatological wind. The volume transport anomaly takes about 10 yr to reach near-full strength in the entire Southern Hemisphere; however, in the Northern Hemisphere, it grows for the duration of the run. The Southern Hemisphere Indo-Pacific volume transport anomaly is about twice the strength of that found in the Atlantic. In the thermocline, water exits the southern westerlies belt in a broad flow that feeds a western boundary current (WBC) in both the Atlantic and Pacific Oceans. These WBCs in turn feed an Indonesian Throughflow from the Pacific and cyclonic gyres in the far north, which are broadly consistent with the Stommel–Arons theory. The deep return flow in each hemisphere is strongly affected by deep-sea ridges, which leads to a number of midocean “WBCs.” The wind perturbation causes isopycnals to sink over most of the basin. After about 20 yr, this sinking is very roughly uniform with latitude, though it varies by basin.
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Hogg, Andrew McC, Paul Spence, Oleg A. Saenko, and Stephanie M. Downes. "The Energetics of Southern Ocean Upwelling." Journal of Physical Oceanography 47, no. 1 (2017): 135–53. http://dx.doi.org/10.1175/jpo-d-16-0176.1.
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AbstractThe ocean’s meridional overturning circulation is closed by the upwelling of dense, carbon-rich waters to the surface of the Southern Ocean. It has been proposed that upwelling in this region is driven by strong westerly winds, implying that the intensification of Southern Ocean winds in recent decades may have enhanced the rate of upwelling, potentially affecting the global overturning circulation. However, there is no consensus on the sensitivity of upwelling to winds or on the nature of the connection between Southern Ocean processes and the global overturning circulation. In this study, the sensitivity of the overturning circulation to changes in Southern Ocean westerly wind stress is investigated using an eddy-permitting ocean–sea ice model. In addition to a suite of standard circulation metrics, an energy analysis is used to aid dynamical interpretation of the model response. Increased Southern Ocean wind stress enhances the upper cell of the overturning circulation through creation of available potential energy in the Southern Hemisphere, associated with stronger upwelling of deep water. Poleward shifts in the Southern Ocean westerlies lead to a complicated transient response, with the formation of bottom water induced by increased polynya activity in the Weddell Sea and a weakening of the upper overturning cell in the Northern Hemisphere. The energetic consequences of the upper overturning cell response indicate an interhemispheric connection to the input of available potential energy in the Northern Hemisphere.
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Arntz, W. E., V. A. Gallardo, D. Gutiérrez, et al. "El Niño and similar perturbation effects on the benthos of the Humboldt, California, and Benguela Current upwelling ecosystems." Advances in Geosciences 6 (March 1, 2006): 243–65. http://dx.doi.org/10.5194/adgeo-6-243-2006.
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Abstract. To a certain degree, Eastern Boundary Current (EBC) ecosystems are similar: Cold bottom water from moderate depths, rich in nutrients, is transported to the euphotic zone by a combination of trade winds, Coriolis force and Ekman transport. The resultant high primary production fuels a rich secondary production in the upper pelagic and nearshore zones, but where O2 exchange is restricted, it creates oxygen minimum zones (OMZs) at shelf and upper slope (Humboldt and Benguela Current) or slope depths (California Current). These hypoxic zones host a specifically adapted, small macro- and meiofauna together with giant sulphur bacteria that use nitrate to oxydise H2S. In all EBC, small polychaetes, large nematodes and other opportunistic benthic species have adapted to the hypoxic conditions and co-exist with sulphur bacteria, which seem to be particularly dominant off Peru and Chile. However, a massive reduction of macrobenthos occurs in the core of the OMZ. In the Humboldt Current area the OMZ ranges between <100 and about 600 m, with decreasing thickness in a poleward direction. The OMZ merges into better oxygenated zones towards the deep sea, where large cold-water mega- and macrofauna occupy a dominant role as in the nearshore strip. The Benguela Current OMZ has a similar upper limit but remains shallower. It also hosts giant sulphur bacteria but little is known about the benthic fauna. However, sulphur eruptions and intense hypoxia might preclude the coexistence of significant mega- und macrobenthos. Conversely, off North America the upper limit of the OMZ is considerably deeper (e.g., 500–600 m off California and Oregon), and the lower boundary may exceed 1000m. The properties described are valid for very cold and cold (La Niña and "normal") ENSO conditions with effective upwelling of nutrient-rich bottom water. During warm (El Niño) episodes, warm water masses of low oxygen concentration from oceanic and equatorial regions enter the upwelling zones, bringing a variety of (sub)tropical immigrants. The autochthonous benthic fauna emigrates to deeper water or poleward, or suffers mortality. However, some local macrofaunal species experience important population proliferations, presumably due to improved oxygenation (in the southern hemisphere), higher temperature tolerance, reduced competition or the capability to use different food. Both these negative and positive effects of El Niño influence local artisanal fisheries and the livelihood of coastal populations. In the Humboldt Current system the hypoxic seafloor at outer shelf depths receives important flushing from the equatorial zone, causing havoc on the sulphur bacteria mats and immediate recolonisation of the sediments by mega- and macrofauna. Conversely, off California, the intruding equatorial water masses appear to have lower oxygen than ambient waters, and may cause oxygen deficiency at upper slope depths. Effects of this change have not been studied in detail, although shrimp and other taxa appear to alter their distribution on the continental margin. Other properties and reactions of the two Pacific EBC benthic ecosystems to El Niño seem to differ, too, as does the overall impact of major episodes (e.g., 1982/1983(1984) vs. 1997/1998). The relation of the "Benguela Niño" to ENSO seems unclear although many Pacific-Atlantic ocean and atmosphere teleconnections have been described. Warm, low-oxygen equatorial water seems to be transported into the upwelling area by similar mechanisms as in the Pacific, but most major impacts on the eukaryotic biota obviously come from other, independent perturbations such as an extreme eutrophication of the sediments ensuing in sulphidic eruptions and toxic algal blooms. Similarities and differences of the Humboldt and California Current benthic ecosystems are discussed with particular reference to ENSO impacts since 1972/73. Where there are data available, the authors include the Benguela Current ecosystem as another important, non-Pacific EBC, which also suffers from the effects of hypoxia.
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Stössel, Achim. "On the impact of sea ice in a global ocean circulation model." Annals of Glaciology 25 (1997): 111–15. http://dx.doi.org/10.1017/s0260305500013884.
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This paper investigates the long-term impact of sea ice on global climate using a global sea-ice–ocean general circulation model (OGCM). The sea-ice component involves state-of-the-art dynamics; the ocean component consists of a 3.5° × 3.5° × 11 layer primitive-equation model. Depending on the physical description of sea ice, significant changes are detected in the convective activity, in the hydrographic properties and in the thermohaline circulation of the ocean model. Most of these changes originate in the Southern Ocean, emphasizing the crucial role of sea ice in this marginally stably stratified region of the world's oceans. Specifically, if the effect of brine release is neglected, the deep layers of the Southern Ocean warm up considerably; this is associated with a weakening of the Southern Hemisphere overturning cell. The removal of the commonly used “salinity enhancement” leads to a similar effect. The deep-ocean salinity is almost unaffected in both experiments. Introducing explicit new-ice thickness growth in partially ice-covered gridcells leads to a substantial increase in convective activity, especially in the Southern Ocean, with a concomitant significant cooling and salinification of the deep ocean. Possible mechanisms for the resulting interactions between sea-ice processes and deep-ocean characteristics are suggested.
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Stössel, Achim. "On the impact of sea ice in a global ocean circulation model." Annals of Glaciology 25 (1997): 111–15. http://dx.doi.org/10.3189/s0260305500013884.
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This paper investigates the long-term impact of sea ice on global climate using a global sea-ice–ocean general circulation model (OGCM). The sea-ice component involves state-of-the-art dynamics; the ocean component consists of a 3.5° × 3.5° × 11 layer primitive-equation model. Depending on the physical description of sea ice, significant changes are detected in the convective activity, in the hydrographic properties and in the thermohaline circulation of the ocean model. Most of these changes originate in the Southern Ocean, emphasizing the crucial role of sea ice in this marginally stably stratified region of the world's oceans. Specifically, if the effect of brine release is neglected, the deep layers of the Southern Ocean warm up considerably; this is associated with a weakening of the Southern Hemisphere overturning cell. The removal of the commonly used “salinity enhancement” leads to a similar effect. The deep-ocean salinity is almost unaffected in both experiments. Introducing explicit new-ice thickness growth in partially ice-covered gridcells leads to a substantial increase in convective activity, especially in the Southern Ocean, with a concomitant significant cooling and salinification of the deep ocean. Possible mechanisms for the resulting interactions between sea-ice processes and deep-ocean characteristics are suggested.
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Cheon, Woo Geun, Young-Gyu Park, J. R. Toggweiler, and Sang-Ki Lee. "The Relationship of Weddell Polynya and Open-Ocean Deep Convection to the Southern Hemisphere Westerlies." Journal of Physical Oceanography 44, no. 2 (2014): 694–713. http://dx.doi.org/10.1175/jpo-d-13-0112.1.
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Abstract The Weddell Polynya of the mid-1970s is simulated in an energy balance model (EBM) sea ice–ocean coupled general circulation model (GCM) with an abrupt 20% increase in the intensity of Southern Hemisphere (SH) westerlies. This small upshift of applied wind stress is viewed as a stand in for the stronger zonal winds that developed in the mid-1970s following a long interval of relatively weak zonal winds between 1954 and 1972. Following the strengthening of the westerlies in this model, the cyclonic Weddell gyre intensifies, raising relatively warm Weddell Sea Deep Water to the surface. The raised warm water then melts sea ice or prevents it from forming to produce the Weddell Polynya. Within the polynya, large heat loss to the air causes surface water to become cold and sink to the bottom via open-ocean deep convection. Thus, the underlying layers cool down, the warm water supply to the surface eventually stops, and the polynya cannot be maintained anymore. During the 100-yr-long model simulation, two Weddell Polynya events are observed. The second one occurs a few years after the first one disappears; it is much weaker and persists for less time than the first one because the underlying layer is cooler. Based on these model simulations, the authors hypothesize that the Weddell Polynya and open-ocean deep convection were responses to the stronger SH westerlies that followed a prolonged weak phase of the southern annular mode.
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Pais, C. "Diet of a deep-sea fish, Hoplostethus mediterraneus, from the south coast of Portugal." Journal of the Marine Biological Association of the United Kingdom 82, no. 2 (2002): 351–52. http://dx.doi.org/10.1017/s002531540200557x.
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The beryciform fish Hoplostethus mediterraneus is a species discarded from the southern Portuguese coastal fisheries. It is taken as by-catch by deep water trawls, at depths of between 234 m and 618 m. This species is a benthopelagic feeder, preying mainly on crustaceans. The dominant prey species encountered were the euphausid Meganyctiphanes norvegica and the amphipod Anilocra physodes. It seems that H. mediterraneus is an opportunistic rather than a selective feeder.
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McMillan, Matthew N., Christopher Izzo, Claudia Junge, Ole Thomas Albert, Armelle Jung, and Bronwyn M. Gillanders. "Analysis of vertebral chemistry to assess stock structure in a deep-sea shark, Etmopterus spinax." ICES Journal of Marine Science 74, no. 3 (2016): 793–803. http://dx.doi.org/10.1093/icesjms/fsw176.
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Deep-sea sharks play a valuable ecological role helping maintain food web balance, yet they are vulnerable to commercial fishing because of slow growth rates and low reproductive capacity. Overfishing of sharks can heavily impact marine ecosystems and the fisheries these support. Knowledge of stock structure is integral to sustainable management of fisheries. The present study analysed vertebral chemistry using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to assay concentrations of 7Li, 23Na, 24Mg, 55Mn, 59Co, 60Ni, 63Cu, 66Zn, 85Rb, 88Sr, 138Ba and 208Pb to assess stock structure in a deep-sea shark, Etmopterus spinax, in Norwegian and French waters. Few studies have applied this technique to elasmobranch vertebrae and the present study represents its first application to a deep-sea shark. Three stocks were identified at the regional scale off western Norway, southern Norway, and France. At finer spatial scales there was evidence of strong population mixing. Overall, the general pattern of stock structure outlined herein provides some indication of the spatial scales at which stocks should be viewed as distinct fisheries management units. The identification of an effective multi-element signature for distinguishing E. spinax stocks utilizing Sr, Ba, Mg, Zn and Pb and the methodological groundwork laid in the present study could also expedite future research into stock structure for E. spinax and deep-sea elasmobranchs more generally.
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Bromwich, David H., Kirstin Werner, Barbara Casati, et al. "The Year of Polar Prediction in the Southern Hemisphere (YOPP-SH)." Bulletin of the American Meteorological Society 101, no. 10 (2020): E1653—E1676. http://dx.doi.org/10.1175/bams-d-19-0255.1.
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AbstractThe Year of Polar Prediction in the Southern Hemisphere (YOPP-SH) had a special observing period (SOP) that ran from 16 November 2018 to 15 February 2019, a period chosen to span the austral warm season months of greatest operational activity in the Antarctic. Some 2,200 additional radiosondes were launched during the 3-month SOP, roughly doubling the routine program, and the network of drifting buoys in the Southern Ocean was enhanced. An evaluation of global model forecasts during the SOP and using its data has confirmed that extratropical Southern Hemisphere forecast skill lags behind that in the Northern Hemisphere with the contrast being greatest between the southern and northern polar regions. Reflecting the application of the SOP data, early results from observing system experiments show that the additional radiosondes yield the greatest forecast improvement for deep cyclones near the Antarctic coast. The SOP data have been applied to provide insights on an atmospheric river event during the YOPP-SH SOP that presented a challenging forecast and that impacted southern South America and the Antarctic Peninsula. YOPP-SH data have also been applied in determinations that seasonal predictions by coupled atmosphere–ocean–sea ice models struggle to capture the spatial and temporal characteristics of the Antarctic sea ice minimum. Education, outreach, and communication activities have supported the YOPP-SH SOP efforts. Based on the success of this Antarctic summer YOPP-SH SOP, a winter YOPP-SH SOP is being organized to support explorations of Antarctic atmospheric predictability in the austral cold season when the southern sea ice cover is rapidly expanding.
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Mandal, Gagan, Shih-Yu Lee, and Jia-Yuh Yu. "The Roles of Wind and Sea Ice in Driving the Deglacial Change in the Southern Ocean Upwelling: A Modeling Study." Sustainability 13, no. 1 (2021): 353. http://dx.doi.org/10.3390/su13010353.
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The Southern Ocean (SO) played a fundamental role in the deglacial climate system by exchanging carbon-rich deep ocean water with the surface. The contribution of the SO’s physical mechanisms toward improving our understanding of SO upwelling’s dynamical changes is developing. Here, we investigated the simulated transient SO atmosphere, ocean, and sea ice evolution during the last deglaciation in a fully coupled Earth system model. Our results showed that decreases in SO upwelling followed the weakening of the Southern Hemisphere surface westerlies, wind stress forcing, and Antarctic sea ice coverage from the Last Glacial Maximum to the Heinrich Stadial 1 and the Younger Dryas. Our results support the idea that the SO upwelling is primarily driven by wind stress forcing. However, during the onset of the Holocene, SO upwelling increased while the strength of the wind stress decreased. The Antarctic sea ice change controlled the salt and freshwater fluxes, ocean density, and buoyancy flux, thereby influencing the SO’s dynamics. Our study highlighted the dynamic linkage of the Southern Hemisphere westerlies, ocean, and sea ice in the SO’s latitudes. Furthermore, it emphasized that zonal wind stress forcing and buoyancy forcing control by sea ice together regulate the change in the SO upwelling.
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Fučkar, Neven S., Shang-Ping Xie, Riccardo Farneti, Elizabeth A. Maroon, and Dargan M. W. Frierson. "Influence of the Extratropical Ocean Circulation on the Intertropical Convergence Zone in an Idealized Coupled General Circulation Model." Journal of Climate 26, no. 13 (2013): 4612–29. http://dx.doi.org/10.1175/jcli-d-12-00294.1.
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Abstract The authors present coupled model simulations in which the ocean's meridional overturning circulation (MOC) sets the zonal mean location of the intertropical convergence zone (ITCZ) in the hemisphere with deep-water production. They use a coarse-resolution single-basin sector coupled general circulation model (CGCM) with simplified atmospheric physics and two idealized land–sea distributions. In an equatorially symmetric closed-basin setting, unforced climate asymmetry develops because of the advective circulation–salinity feedback that amplifies the asymmetry of the deep-MOC cell and the upper-ocean meridional salinity transport. It confines the deep-water production and the dominant extratropical ocean heat release to a randomly selected hemisphere. The resultant ocean heat transport (OHT) toward the hemisphere with the deep-water source is partially compensated by the atmospheric heat transport (AHT) across the equator via an asymmetric Hadley circulation, setting the ITCZ in the hemisphere warmed by the ocean. When a circumpolar channel is open at subpolar latitudes, the circumpolar current disrupts the poleward transport of the upper-ocean saline water and suppresses deep-water formation poleward of the channel. The MOC adjusts by lowering the main pycnocline and shifting the deep-water production into the opposite hemisphere from the channel, and the ITCZ location follows the deep-water source again because of the Hadley circulation adjustment to cross-equatorial OHT. The climate response is sensitive to the sill depth of the channel but becomes saturated when the sill is deeper than the main pycnocline depth in subtropics. In simulations with a circumpolar channel, the ITCZ is in the Northern Hemisphere (NH) because of the Southern Hemisphere (SH) circumpolar flow that forces northward OHT.
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Latif, Mojib, Torge Martin, and Wonsun Park. "Southern Ocean Sector Centennial Climate Variability and Recent Decadal Trends." Journal of Climate 26, no. 19 (2013): 7767–82. http://dx.doi.org/10.1175/jcli-d-12-00281.1.
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Abstract Evidence is presented for the notion that some contribution to the recent decadal trends observed in the Southern Hemisphere, including the lack of a strong Southern Ocean surface warming, may have originated from longer-term internal centennial variability originating in the Southern Ocean. The existence of such centennial variability is supported by the instrumental sea surface temperatures (SSTs), a multimillennial reconstruction of Tasmanian summer temperatures from tree rings, and a millennial control integration of the Kiel Climate Model (KCM). The model variability was previously shown to be linked to changes in Weddell Sea deep convection. During phases of deep convection the surface Southern Ocean warms, the abyssal Southern Ocean cools, Antarctic sea ice extent retreats, and the low-level atmospheric circulation over the Southern Ocean weakens. After the halt of deep convection the surface Southern Ocean cools, the abyssal Southern Ocean warms, Antarctic sea ice expands, and the low-level atmospheric circulation over the Southern Ocean intensifies, consistent with what has been observed during the recent decades. A strong sensitivity of the time scale to model formulation is noted. In the KCM, the centennial variability is associated with global-average surface air temperature (SAT) changes of the order of a few tenths of a degree per century. The model results thus suggest that internal centennial variability originating in the Southern Ocean should be considered in addition to other internal variability and external forcing when discussing the climate of the twentieth century and projecting that of the twenty-first century.
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Tsang, L. M., T. Y. Chan, M. K. Cheung, and K. H. Chu. "Molecular evidence for the Southern Hemisphere origin and deep-sea diversification of spiny lobsters (Crustacea: Decapoda: Palinuridae)." Molecular Phylogenetics and Evolution 51, no. 2 (2009): 304–11. http://dx.doi.org/10.1016/j.ympev.2009.01.015.
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Thompson, Andrew F., Sophia K. Hines, and Jess F. Adkins. "A Southern Ocean Mechanism for the Interhemispheric Coupling and Phasing of the Bipolar Seesaw." Journal of Climate 32, no. 14 (2019): 4347–65. http://dx.doi.org/10.1175/jcli-d-18-0621.1.
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Abstract The last glacial period is punctuated by abrupt changes in Northern Hemisphere temperatures that are known as Dansgaard–Oeschger (DO) events. A striking and largely unexplained feature of DO events is an interhemispheric asymmetry characterized by cooling in Antarctica during periods of warming in Greenland and vice versa—the bipolar seesaw. Methane-synchronized ice core records indicate that the Southern Hemisphere lags the Northern Hemisphere by approximately 200 years. Here, we propose a mechanism that produces observed features of both the bipolar seesaw and the phasing of DO events. The spatial pattern of sea ice formation and melt in the Southern Ocean imposes a rigid constraint on where water masses are modified: waters are made denser near the coast where ice forms and waters are made lighter farther north where ice melts. This pattern, coupled to the tilt of density surfaces across the Southern Ocean and the stratification of the ocean basins, produces two modes of overturning corresponding to different bipolar seesaw states. We present evolution equations for a simplified ocean model that describes the transient adjustment of the basin stratification, the Southern Ocean surface density distribution, and the overturning strength as the ocean moves between these states in response to perturbations in North Atlantic Deep Water formation, which we take as a proxy for Greenland temperatures. Transitions between different overturning states occur over a multicentennial time scale, which is qualitatively consistent with the observed Southern Hemisphere lag. The volume of deep density layers varies inversely with the overturning strength, leading to significant changes in residence times. Evidence of these dynamics in more realistic circulation models is discussed.
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Hoskins, B. J., and K. I. Hodges. "A New Perspective on Southern Hemisphere Storm Tracks." Journal of Climate 18, no. 20 (2005): 4108–29. http://dx.doi.org/10.1175/jcli3570.1.
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Abstract A detailed view of Southern Hemisphere storm tracks is obtained based on the application of filtered variance and modern feature-tracking techniques to a wide range of 45-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) data. It has been checked that the conclusions drawn in this study are valid even if data from only the satellite era are used. The emphasis of the paper is on the winter season, but results for the four seasons are also discussed. Both upper- and lower-tropospheric fields are used. The tracking analysis focuses on systems that last longer than 2 days and are mobile (move more than 1000 km). Many of the results support previous ideas about the storm tracks, but some new insights are also obtained. In the summer there is a rather circular, strong, deep high-latitude storm track. In winter the high-latitude storm track is more asymmetric with a spiral from the Atlantic and Indian Oceans in toward Antarctica and a subtropical jet–related lower-latitude storm track over the Pacific, again tending to spiral poleward. At all times of the year, maximum storm activity in the higher-latitude storm track is in the Atlantic and Indian Ocean regions. In the winter upper troposphere, the relative importance of, and interplay between, the subtropical and subpolar storm tracks is discussed. The genesis, lysis, and growth rate of lower-tropospheric winter cyclones together lead to a vivid picture of their behavior that is summarized as a set of overlapping plates, each composed of cyclone life cycles. Systems in each plate appear to feed the genesis in the next plate through downstream development in the upper-troposphere spiral storm track. In the lee of the Andes in South America, there is cyclogenesis associated with the subtropical jet and also, poleward of this, cyclogenesis largely associated with system decay on the upslope and regeneration on the downslope. The genesis and lysis of cyclones and anticyclones have a definite spatial relationship with each other and with the Andes. At 500 hPa, their relative longitudinal positions are consistent with vortex-stretching ideas for simple flow over a large-scale mountain. Cyclonic systems near Antarctica have generally spiraled in from lower latitudes. However, cyclogenesis associated with mobile cyclones occurs around the Antarctic coast with an interesting genesis maximum over the sea ice near 150°E. The South Pacific storm track emerges clearly from the tracking as a coherent deep feature spiraling from Australia to southern South America. A feature of the summer season is the genesis of eastward-moving cyclonic systems near the tropic of Capricorn off Brazil, in the central Pacific and, to a lesser extent, off Madagascar, followed by movement along the southwest flanks of the subtropical anticyclones and contribution to the “convergence zone” cloud bands seen in these regions.
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Sen Gupta, Alexander, Agus Santoso, Andréa S. Taschetto, Caroline C. Ummenhofer, Jessica Trevena, and Matthew H. England. "Projected Changes to the Southern Hemisphere Ocean and Sea Ice in the IPCC AR4 Climate Models." Journal of Climate 22, no. 11 (2009): 3047–78. http://dx.doi.org/10.1175/2008jcli2827.1.
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Abstract Fidelity and projected changes in the climate models, used for the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4), are assessed with regard to the Southern Hemisphere extratropical ocean and sea ice systems. While individual models span different physical parameterizations and resolutions, a major component of intermodel variability results from surface wind differences. Projected changes to the surface wind field are also central in modifying future extratropical circulation and internal properties. A robust southward shift of the circumpolar current and subtropical gyres is projected, with a strong spinup of the Atlantic gyre. An associated increase in the core strength of the circumpolar circulation is evident; however, this does not translate into robust increases in Drake Passage transport. While an overarching oceanic warming is projected, the circulation-driven poleward shift of the temperature field explains much of the midlatitude warming pattern. The effect of this shift is less clear for salinity, where, instead, surface freshwater forcing dominates. Surface warming and high-latitude freshwater increases drive intensified stratification, and a shoaling and southward shift of the deep mixed layers. Despite large intermodel differences, there is also a robust weakening in bottom water formation and its northward outflow. At the same time the wind intensification invigorates the upwelling of deep water, transporting warm, salty water southward and upward, with major implications for sequestration and outgassing of CO2. A robust decrease is projected for both the sea ice concentration and the seasonal cycling of ice volume, potentially altering the salt and heat budget at high latitudes.
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Salgado, Enrique J., Stephanie E. Nehasil, and Peter J. Etnoyer. "Distribution of deep-water corals, sponges, and demersal fisheries landings in Southern California, USA: implications for conservation priorities." PeerJ 6 (October 10, 2018): e5697. http://dx.doi.org/10.7717/peerj.5697.
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Deep-sea corals in Southern California are diverse and abundant but subject to multiple stressors, including bottom-contact fisheries using mobile and fixed gear. There is a need for more information on the distribution of these taxa in relation to the distribution of demersal fishing effort, and the distribution of marine protected areas, in order to improve spatial planning. There are many marine managed areas in Southern California, including essential fish habitat (EFH) areas, conservation areas, and a national marine sanctuary, but specific areas of overlap between bottom fishing and benthic epifauna are poorly known. Groundfish surveys were conducted by the National Marine Fisheries Service using a remotely operated vehicle throughout Southern California between 2003 and 2011 to document abundance and distribution of deep-water rockfish and flatfish to a depth of 500 m. Corals and sponges were also common in these images, providing an opportunity to examine these communities. Analyses of 34,792 still images revealed abundance and diversity of coral and sponge taxa, as well as frequency of fishing debris. The occurrence data were overlaid in a geographic information system with landings data for deep-water (>50 m) demersal fisheries to identify areas of spatial overlap. Corals or sponges were observed in 23% of images. A total of 15 coral genera and six sponge morphotypes were identified. A total of 70 species codes were targeted by deep-water demersal fisheries operating below 50 m for years 2007–2011. A novel priority-setting algorithm was developed to identify areas of high richness, abundance, and fishing intensity (RAFi). Several highly-ranked areas were already protected as EFH (Footprint, Piggy Bank). Other highly-ranked sites (West Catalina Island, San Clemente Island, 9-Mile Bank, Santa Rosa Flats) were encompassed by transient gear restrictions, such as Rockfish conservation areas, but are now recommended for permanent protection by the Pacific Fishery Management Council.
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Tachikawa, K., A. Timmermann, L. Vidal, C. Sonzogni, and O. E. Timm. "Southern Hemisphere orbital forcing and its effects on CO<sub>2</sub> and tropical Pacific climate." Climate of the Past Discussions 9, no. 2 (2013): 1869–900. http://dx.doi.org/10.5194/cpd-9-1869-2013.
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Abstract. The western Pacific warm pool (WPWP) is an important heat source for the atmospheric circulation and influences climate conditions worldwide. Understanding its sensitivity to past radiative perturbations may help better contextualize the magnitudes and patterns of current and projected tropical climate change. Here we present a new Mg/Ca-based sea surface temperature (SST) reconstruction over the past 400 kyr from the Bismarck Sea, off Papua New Guinea, along with results from a transient earth system model simulation. Our results document the primary influence of CO2 forcing on glacial/interglacial WPWP SSTs and secondary effects due to changes in wind-driven tropical boundary currents. In addition to the SST, deep ocean temperature reconstructions from this core are linked with Southern Ocean temperature and sea-ice variations on timescales of ~ 23 kyr. It is proposed that Southern Hemisphere insolation changes serve as pacemaker for sea-ice variations in the Southern Ocean, which in turn modulate windstress curl-driven upwelling of carbon-rich waters, hence controlling atmospheric CO2 and tropical WPWP temperatures.
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Denton, George H., Terence J. Hughes, and Wibjörn Karlén. "Global Ice-Sheet System Interlocked by Sea Level." Quaternary Research 26, no. 1 (1986): 3–26. http://dx.doi.org/10.1016/0033-5894(86)90081-5.
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Denton and Hughes (1983, Quaternary Research 20, 125–144) postulated that sea level linked a global ice-sheet system with both terrestrial and grounded marine components during late Quaternary ice ages. Summer temperature changes near Northern Hemisphere melting margins initiated sea-level fluctuations that controlled marine components in both polar hemispheres. It was further proposed that variations of this ice-sheet system amplified and transmitted Milankovitch summer half-year insolation changes between 45 and 75°N into global climatic changes. New tests of this hypothesis implicate sea level as a major control of the areal extent of grounded portions of the Antarctic Ice Sheet, thus fitting the concept of a globally interlocked ice-sheet system. But recent atmospheric modeling results (Manabe and Broccoli, 1985, Journal of Geophysical Research 90, 2167–2190) suggest that factors other than areal changes of the grounded Antarctic Ice Sheet strongly influenced Southern Hemisphere climate and terminated the last ice age simultaneously in both polar hemispheres. Atmospheric carbon dioxide linked to high-latitude oceans is the most likely candidate (Shackleton and Pisias, 1985, Atmospheric carbon dioxide, orbital forcing, and climate. In “The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present” (E. T. Sundquest and W. S. Broecker, Eds.), pp. 303–318. Geophysical Monograph 32, American Geophysical Union, Washington, D.C.), but another potential influence was high-frequency climatic oscillations (2500 yr). It is postulated that variations in atmospheric carbon dioxide acted through an Antarctic ice shelf linked to the grounded ice sheet to produce and terminate Southern Hemisphere ice-age climate. It is further postulated that Milankovitch summer insolation combined with a warm high-frequency oscillation caused marked recession of Northern Hemisphere ice-sheet melting margins and the North Atlantic polar front about 14,000 14C yr B.P. This permitted renewed formation of North Atlantic Deep Water, which could well have controlled atmospheric carbon dioxide (W. S. Broecker, D. M. Peteet, and D. Rind, 1985, Nature (London) 315, 21–26). Combined melting and consequent sea-level rise from the three warming factors initiated irreversible collapse of the interlocked global ice-sheet system, which was at its largest but most vulnerable configuration.
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Mikolajewicz, Uwf. "Effect of meltwater input from the Antarctic ice sheet on the thermohaline circulation." Annals of Glaciology 27 (1998): 311–15. http://dx.doi.org/10.3189/1998aog27-1-311-315.
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The potential effect of meltwater input from the Antarctic ice sheet is studied in sensitivity experiments with an ocean general circulation model coupled to an energy-balance model of the atmosphere. The effect is generally a reduction of surface salinity and deep convection in The Southern Ocean, associated with surface cooling. There is an accompanying, delayed intensification of the overturning in the Northern Hemisphere, leading to warmer conditions over both the North Atlantic and North Pacific With a sufficiently large meltwater pulse it is possible to trigger switches between different steady states of the ocean's thermohaline circulation, which differ mainly in the formation rates of North Atlantic Deep Water. Thus a transient perturbation in the Southern Ocean can lead to long-term climate changes in both hemispheres. The model reacts morè sensitively to melt water input into theWeddell Sea than into the Ross Sea.
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KUBERAN, G., REKHA DEVI CHAKRABORTY, P. PURUSHOTHAMAN, G. MAHESWARUDU, L. SREESANTH, and N. RAGESH. "A new record of deep-sea shrimp Glyphocrangon investigatoris Wood-Mason & Alcock, 1891 (Decapoda: Glyphocrangonidae) from the southeastern Arabian Sea." Zootaxa 4612, no. 4 (2019): 566. http://dx.doi.org/10.11646/zootaxa.4612.4.8.
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Here, we report the new record of deep-sea caridean shrimp Glyphocrangon investigatoris Wood-Mason & Alcock, 1891 from the Arabian Sea along the Indian coast. The three individual specimens were collected from Sakthikulangara fish landing center (fishing off Kollam 8°56’60.78”N/76°32’34.27”E) obtained from deep-sea bottom trawlers between 200 and 300 m depth along the southwest coast of India in December of 2017 and the voucher specimen was deposited to the Marine Biodiversity Referral Museum at Central Marine Fisheries Research Institute. The species of G. investigatoris is considered as one of the data deficient in distributional range, which was only recorded from northern and southern Bay of Bengal. The intraspecies genetic distance in the COI gene of G. investigatoris retrieved from NCBI revealed 0.6–0.7% while interspecies distance ranged from 5% to 26.5% and 16S was found between 1.1% to 8.1% and the closest genetic distance ranged with G. regalis.
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Schmittner, A., and D. C. Lund. "Carbon isotopes support Atlantic meridional overturning circulation decline as a trigger for early deglacial CO<sub>2</sub> rise." Climate of the Past Discussions 10, no. 4 (2014): 2857–93. http://dx.doi.org/10.5194/cpd-10-2857-2014.
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Abstract. The mechanism for the observed initial rise of atmospheric CO2 during the last deglaciation remains unknown. Most recent hypotheses invoke Southern Hemisphere processes such as shifts in mid-latitude westerly winds. Here we compare simulations from a global, coupled climate-biogeochemistry model including carbon isotopes (δ13C) with a synthesis of high-resolution deep sea δ13C reconstructions as well as ice core data. The reconstructions from Heinrich Stadial Event 1 (HS1, ~ 19–15 ka BP) are constistent with model simulations of a large multi-millennial reduction of the Atlantic Meridional Overturning Circulation (AMOC). Our results suggest that the rise in atmospheric CO2 and decrease in its δ13C composition (δ13CO2) observed during the early deglacial may have been caused by an AMOC induced decline of the ocean's biologically sequestered carbon storage without the need to invoke changes in Southern Hemisphere winds.
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Fernandes, Paul G., Pete Stevenson, Andrew S. Brierley, Frederick Armstrong, and E. John Simmonds. "Autonomous underwater vehicles: future platforms for fisheries acoustics." ICES Journal of Marine Science 60, no. 3 (2003): 684–91. http://dx.doi.org/10.1016/s1054-3139(03)00038-9.
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Abstract Autonomous underwater vehicles (AUVs) are unmanned submersibles that can be pre-programmed to navigate in three dimensions under water. The technological advances required for reliable deployment, mission control, performance, and recovery of AUVs have developed considerably over the past 10 years. Currently, there are several vehicles operating successfully in the offshore industries as well as in the applied and academic oceanographic sciences. This article reviews the application of AUVs to fisheries- and plankton-acoustics research. Specifications of the main AUVs currently in operation are given. Compared to traditional platforms for acoustic instruments, AUVs can sample previously impenetrable environments such as the sea surface, the deep sea, and under-sea ice. Furthermore, AUVs are typically small, quiet, and have the potential to operate at low cost and be unconstrained by the vagaries of weather. Examples of how these traits may be utilized in fisheries-acoustics science are given with reference to previous work in the North Sea and Southern Ocean and to potential future applications. Concurrent advances in multi-beam sonar technology and species identification, using multi-frequency and broadband sonars, will further enhance the utility of AUVs for fisheries acoustics. However, before many of the more prospective applications can be accomplished, advances in power-source technology are required to increase the range of operation. The paper ends by considering developments that may turn AUVs from objects sometimes perceived as science fiction into instruments used routinely to gather scientific facts.
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Aiken, Christopher M., and Matthew H. England. "Sensitivity of the Present-Day Climate to Freshwater Forcing Associated with Antarctic Sea Ice Loss." Journal of Climate 21, no. 15 (2008): 3936–46. http://dx.doi.org/10.1175/2007jcli1901.1.
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Abstract The role played by Southern Hemisphere sea ice in the global climate system is explored using an earth system climate model of intermediate complexity. An ensemble of experiments is analyzed in which freshwater forcing equivalent to a complete 100-yr meltback of Southern Hemisphere sea ice is applied to a model run that simulates the present climate. This freshwater forcing acts to mildy subdue Southern Ocean deep overturning, reducing mean Antarctic Bottom Water (AABW) export by 0.5 Sv (1 Sv ≡ 106 m3 s−1) in the ensemble average. The decreased convective overturning cools the surface waters, thereby increasing sea ice volume and thus forming a negative feedback that stabilizes Antarctic sea ice. In contrast, the reduced convective overturn warms subsurface waters in the Southern Ocean, which, combined with the imposed freshening, results in a reduction in the meridional steric height gradient and hence a slowdown of the Antarctic Circumpolar Current (ACC). The reduction in ACC strength is, however, only modest at 1.5 Sv. These responses are thus of only weak magnitude, and the system recovers to its original state over time scales of decades. An extreme scenario experiment with essentially instantaneous addition of this meltwater load shows similar results, indicating the limited response of the climate system to the freshening implied by Antarctic sea ice melt. An additional experiment in which a much larger freshwater forcing of approximately 0.4 Sv is applied over 100 yr confirms the relatively weak response of the model’s climate state to such forcing, relative to the well-documented climatic effects of freshwater forcing added to the North Atlantic.
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Miyasaka, Takafumi, and Hisashi Nakamura. "Structure and Mechanisms of the Southern Hemisphere Summertime Subtropical Anticyclones." Journal of Climate 23, no. 8 (2010): 2115–30. http://dx.doi.org/10.1175/2009jcli3008.1.
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Abstract The three-dimensional structure and dynamics of the climatological-mean summertime subtropical anticyclones in the Southern Hemisphere (SH) are investigated. As in the Northern Hemisphere (NH), each of the surface subtropical anticyclones over the South Pacific, South Atlantic, and South Indian Oceans is accompanied by a meridional vorticity dipole aloft, exhibiting barotropic and baroclinic structures in its poleward and equatorward portions, respectively, in a manner that is dynamically consistent with the observed midtropospheric subsidence. Their dynamics are also similar to their NH counterpart. It is demonstrated through the numerical experiments presented here that each of the SH surface anticyclones observed over the relatively cool eastern oceans can be reproduced as a response to a local near-surface cooling–heating couplet. The cooling is mainly due to radiative cooling associated with low-level maritime clouds, and the heating to the east is due to sensible heat flux over the dry, heated continental surface. The low-level clouds act to maintain the coolness of the underlying ocean surface, which is also maintained by the alongshore surface southerlies. As in the NH, the presence of a local atmosphere–ocean–land feedback loop is thus suggested, in which the summertime subtropical anticyclones and continental cyclones to their east are involved. Both the model experiments conducted here and the diagnosed upward flux of Rossby wave activity suggest that, in addition to continental deep convective heating, the land–sea heating–cooling contrasts across the west coasts of the three continents can contribute to the formation of the summertime upper-level planetary wave pattern observed in the entire subtropical SH, characterized by the zonal wavenumber-3 component. Though rather subtle, there are some interhemispheric differences in the summertime subtropical anticyclones, including their smaller magnitudes in the SH and the stronger equatorward propagation of upper-level Rossby wave activity emanating from the SH surface anticyclones.
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Han, MyeongHee, Igor Kamenkovich, Timour Radko, and William E. Johns. "Relationship between Air–Sea Density Flux and Isopycnal Meridional Overturning Circulation in a Warming Climate." Journal of Climate 26, no. 8 (2013): 2683–99. http://dx.doi.org/10.1175/jcli-d-11-00682.1.
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Abstract This study aims to explore the relationship between air–sea density flux and isopycnal meridional overturning circulation (MOC), using the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) model projections of the twenty-first-century climate. The focus is on the semiadiabatic component of MOC beneath the mixed layer; this component is described using the concept of the push–pull mode, which represents the combined effects of the adiabatic push into the deep ocean in the Northern Hemisphere and the pull out of the deep ocean in the Southern Hemisphere. The analysis based on the GFDL Climate Model version 2.1 (CM2.1) simulation demonstrates that the push–pull mode and the actual isopycnal MOC at the equator evolve similarly in the deep layers, with their maximum transports decreasing by 4–5 Sv (1 Sv ≡ 106 m3 s−1) during years 2001–2100. In particular, the push–pull mode and actual isopycnal MOC are within approximately 10% of each other at the density layers heavier than 27.55 kg m−3, where the reduction in the MOC strength is the strongest. The decrease in the push–pull mode is caused by the direct contribution of the anomalous heat, rather than freshwater, surface fluxes. The agreement between the deep push–pull mode and MOC in the values of linear trend and variability on time scales longer than a decade suggests a largely adiabatic pole-to-pole mechanism for these changes. The robustness of the main conclusions is further explored in additional model simulations.
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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 (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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Chikamoto, M. O., A. Abe-Ouchi, A. Oka, R. Ohgaito, and A. Timmermann. "Quantifying the ocean's role in glacial CO<sub>2</sub> reductions." Climate of the Past 8, no. 2 (2012): 545–63. http://dx.doi.org/10.5194/cp-8-545-2012.
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Abstract. A series of Last Glacial Maximum (LGM) marine carbon cycle sensitivity experiments is conducted to test the effect of different physical processes, as simulated by two atmosphere-ocean general circulation model (AOGCM) experiments, on atmospheric pCO2. One AOGCM solution exhibits an increase in North Atlantic Deep Water (NADW) formation under glacial conditions, whereas the other mimics an increase in Antarctic Bottom Water (AABW) associated with a weaker NADW. None of these sensitivity experiments reproduces the observed magnitude of glacial/interglacial pCO2 changes. However, to explain the reconstructed vertical gradient of dissolved inorganic carbon (DIC) of 40 mmol m−3 a marked enhancement in AABW formation is required. Furthermore, for the enhanced AABW sensitivity experiment the simulated stable carbon isotope ratio (δ13C) decreases by 0.4‰ at intermediate depths in the South Atlantic in accordance with sedimentary evidence. The shift of deep and bottom water formation sites from the North Atlantic to the Southern Ocean increases the total preformed nutrient inventory, so that the lowered efficiency of Southern Ocean nutrient utilization in turn increases atmospheric pCO2. This change eventually offsets the effect of an increased abyssal carbon pool due to stronger AABW formation. The effects of interhemispheric glacial sea-ice changes on atmospheric pCO2 oppose each other. Whereas, extended sea-ice coverage in the Southern Hemisphere reduces the air-sea gas exchange of CO2 in agreement with previous theoretical considerations, glacial advances of sea-ice in the Northern Hemisphere lead to a weakening of the oceanic carbon uptake through the physical pump. Due to enhanced gas solubility associated with lower sea surface temperature, both glacial experiments generate a reduction of atmospheric pCO2 by about 20–23 ppmv. The sensitivity experiments presented here demonstrate the presence of compensating effects of different physical processes in the ocean on glacial CO2 and the difficulty of finding a simple explanation of the glacial CO2 problem by invoking ocean dynamical changes.
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Holland, Marika M., Cecilia M. Bitz, Elizabeth C. Hunke, William H. Lipscomb, and Julie L. Schramm. "Influence of the Sea Ice Thickness Distribution on Polar Climate in CCSM3." Journal of Climate 19, no. 11 (2006): 2398–414. http://dx.doi.org/10.1175/jcli3751.1.
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Abstract The sea ice simulation of the Community Climate System Model version 3 (CCSM3) T42-gx1 and T85-gx1 control simulations is presented and the influence of the parameterized sea ice thickness distribution (ITD) on polar climate conditions is examined. This includes an analysis of the change in mean climate conditions and simulated sea ice feedbacks when an ITD is included. It is found that including a representation of the subgrid-scale ITD results in larger ice growth rates and thicker sea ice. These larger growth rates represent a higher heat loss from the ocean ice column to the atmosphere, resulting in warmer surface conditions. Ocean circulation, most notably in the Southern Hemisphere, is also modified by the ITD because of the influence of enhanced high-latitude ice formation on the ocean buoyancy flux and resulting deep water formation. Changes in atmospheric circulation also result, again most notably in the Southern Hemisphere. There are indications that the ITD also modifies simulated sea ice–related feedbacks. In regions of similar ice thickness, the surface albedo changes at 2XCO2 conditions are larger when an ITD is included, suggesting an enhanced surface albedo feedback. The presence of an ITD also modifies the ice thickness–ice strength relationship and the ice thickness–ice growth rate relationship, both of which represent negative feedbacks on ice thickness. The net influence of the ITD on polar climate sensitivity and variability results from the interaction of these and other complex feedback processes.
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Machado, Jeferson Prietsch, Flavio Justino, and Luciano Ponzi Pezzi. "Impacts of Wind Stress Changes on the Global Heat Transport, Baroclinic Instability, and the Thermohaline Circulation." Advances in Meteorology 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/2089418.
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The wind stress is a measure of momentum transfer due to the relative motion between the atmosphere and the ocean. This study aims to investigate the anomalous pattern of atmospheric and oceanic circulations due to 50% increase in the wind stress over the equatorial region and the Southern Ocean. In this paper we use a coupled climate model of intermediate complexity (SPEEDO). The results show that the intensification of equatorial wind stress causes a decrease in sea surface temperature in the tropical region due to increased upwelling and evaporative cooling. On the other hand, the intensification of wind stress over the Southern Ocean induces a regional increase in the air and sea surface temperatures which in turn leads to a reduction in Antarctic sea ice thickness. This occurs in association with changes in the global thermohaline circulation strengthening the rate of Antarctic Bottom Water formation and a weakening of the North Atlantic Deep Water. Moreover, changes in the Southern Hemisphere thermal gradient lead to modified atmospheric and oceanic heat transports reducing the storm tracks and baroclinic activity.
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Xie, Shang-Ping, Qihua Peng, Youichi Kamae, Xiao-Tong Zheng, Hiroki Tokinaga, and Dongxiao Wang. "Eastern Pacific ITCZ Dipole and ENSO Diversity." Journal of Climate 31, no. 11 (2018): 4449–62. http://dx.doi.org/10.1175/jcli-d-17-0905.1.
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Abstract The eastern tropical Pacific features strong climatic asymmetry across the equator, with the intertropical convergence zone (ITCZ) displaced north of the equator most of time. In February–April (FMA), the seasonal warming in the Southern Hemisphere and cooling in the Northern Hemisphere weaken the climatic asymmetry, and a double ITCZ appears with a zonal rainband on either side of the equator. Results from an analysis of precipitation variability reveal that the relative strength between the northern and southern ITCZ varies from one year to another and this meridional seesaw results from ocean–atmosphere coupling. Surprisingly this meridional seesaw is triggered by an El Niño–Southern Oscillation (ENSO) of moderate amplitudes. Although ENSO is originally symmetric about the equator, the asymmetry in the mean climate in the preceding season introduces asymmetric perturbations, which are then preferentially amplified by coupled ocean–atmosphere feedback in FMA when deep convection is sensitive to small changes in cross-equatorial gradient of sea surface temperature. This study shows that moderate ENSO follows a distinct decay trajectory in FMA and southeasterly cross-equatorial wind anomalies cause moderate El Niño to dissipate rapidly as southeasterly cross-equatorial wind anomalies intensify ocean upwelling south of the equator. In contrast, extreme El Niño remains strong through FMA as enhanced deep convection causes westerly wind anomalies to intrude and suppress ocean upwelling in the eastern equatorial Pacific.
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Van Vliet-Lanoë, Brigitte, Jean-Luc Schneider, Águst Guðmundsson, et al. "Eemian estuarine record forced by glacio-isostasy (southern Iceland)—link with Greenland and deep sea records." Canadian Journal of Earth Sciences 55, no. 2 (2018): 154–71. http://dx.doi.org/10.1139/cjes-2017-0126.
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Central southern Iceland is one of the main outlets of the Icelandic Ice Sheet where a MIS 5e sedimentary complex, the Rangá Formation, is extensively observed below the last deglaciation terminal moraines. Sedimentary facies demonstrate that the Rangá Formation is mostly tidal, up to 215 m (transgression I) and 168 m (transgression II) in altitude. The first highstand reworks a thick tephra from the Grimsvötn volcano, known in marine cores as 5e low/Bas-IV and positioned at ca. 127 Ka BP, the Eemian thermal optimum. This formation is related to a rapid deglaciation followed by two marine transgressions marked by the development of extended mud flats, which were separated by a complex regression phase, associated with loess deposition, ca. 9 Ka in duration. Palaeo jökulhlaups, basaltic flows, and tephra fallouts from the Hekla and Grimsvötn volcanoes affected the sedimentation. The Rangá Formation yields one of the first continuous and complete estuarine records of the Eemian interglacial in Iceland and probably for most of the northern terrestrial Atlantic. This estuarine infill records the distal signature of a complex glacial advance within the last interglacial, already well identified in northern and central Iceland. The glacial advance is attributed to the intra-Eemian cooling events (Greenland GS 26 or marine cold events M-C25-C26). It is followed by a warming and a glacial retreat corresponding to the Greenland GI 25 event. This formation allows, in connection with the timing of recognized volcanic periods, a better insight of the interconnections between sea-level, regional glacial extent, and Northern Hemisphere marine and ice core climatic records.
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Jullion, Loïc, Alberto C. Naveira Garabato, Michael P. Meredith, Paul R. Holland, Peggy Courtois, and Brian A. King. "Decadal Freshening of the Antarctic Bottom Water Exported from the Weddell Sea." Journal of Climate 26, no. 20 (2013): 8111–25. http://dx.doi.org/10.1175/jcli-d-12-00765.1.
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Abstract Recent decadal changes in Southern Hemisphere climate have driven strong responses from the cryosphere. Concurrently, there has been a marked freshening of the shelf and bottom waters across a wide sector of the Southern Ocean, hypothesized to be caused by accelerated glacial melt in response to a greater flux of warm waters from the Antarctic Circumpolar Current onto the shelves of West Antarctica. However, the circumpolar pattern of changes has been incomplete: no decadal freshening in the deep layers of the Atlantic sector has been observed. In this study, the authors document a significant freshening of the Antarctic Bottom Water exported from the Weddell Sea, which is the source for the abyssal layer of the Atlantic overturning circulation, and trace its possible origin to atmospheric-forced changes in the ice shelves and sea ice on the eastern flank of the Antarctic Peninsula that include an anthropogenic component. These findings suggest that the expansive and relatively cool Weddell gyre does not insulate the bottom water formation regions in the Atlantic sector from the ongoing changes in climatic forcing over the Antarctic region.
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Otterå, O. H., M. Bentsen, I. Bethke, and N. G. Kvamstø. "Simulated pre-industrial climate in Bergen Climate Model (version 2): model description and large-scale circulation features." Geoscientific Model Development 2, no. 2 (2009): 197–212. http://dx.doi.org/10.5194/gmd-2-197-2009.
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Abstract. The Bergen Climate Model (BCM) is a fully-coupled atmosphere-ocean-sea-ice model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate. Here, a pre-industrial multi-century simulation with an updated version of BCM is described and compared to observational data. The model is run without any form of flux adjustments and is stable for several centuries. The simulated climate reproduces the general large-scale circulation in the atmosphere reasonably well, except for a positive bias in the high latitude sea level pressure distribution. Also, by introducing an updated turbulence scheme in the atmosphere model a persistent cold bias has been eliminated. For the ocean part, the model drifts in sea surface temperatures and salinities are considerably reduced compared to earlier versions of BCM. Improved conservation properties in the ocean model have contributed to this. Furthermore, by choosing a reference pressure at 2000 m and including thermobaric effects in the ocean model, a more realistic meridional overturning circulation is simulated in the Atlantic Ocean. The simulated sea-ice extent in the Northern Hemisphere is in general agreement with observational data except for summer where the extent is somewhat underestimated. In the Southern Hemisphere, large negative biases are found in the simulated sea-ice extent. This is partly related to problems with the mixed layer parametrization, causing the mixed layer in the Southern Ocean to be too deep, which in turn makes it hard to maintain a realistic sea-ice cover here. However, despite some problematic issues, the pre-industrial control simulation presented here should still be appropriate for climate change studies requiring multi-century simulations.
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Otterå, O. H., M. Bentsen, I. Bethke, and N. G. Kvamstø. "Simulated pre-industrial climate in Bergen Climate Model (version 2): model description and large-scale circulation features." Geoscientific Model Development Discussions 2, no. 1 (2009): 507–49. http://dx.doi.org/10.5194/gmdd-2-507-2009.
Full textAbstract:
Abstract. The Bergen Climate Model (BCM) is a fully-coupled atmosphere-ocean-sea-ice model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate. Here, a pre-industrial multi-century simulation with an updated version of BCM is described and compared to observational data. The model is run without any form of flux adjustments and is stable for several centuries. The simulated climate reproduces the general large scale circulation in the atmosphere reasonably well, except for a positive bias in the high latitude sea level pressures distribution. Also, by introducing an updated turbulence scheme in the atmosphere model a persistent cold bias has been eliminated. For the ocean part, the model drifts in sea surface temperatures and salinities are considerably reduced compared to earlier versions of BCM. Improved conservation properties in the ocean have contributed to this. Furthermore, by choosing a reference pressure at 2000 m and including thermobaric effects in the ocean model, a more realistic meridional overturning circulation is simulated in the Atlantic Ocean. The simulated sea-ice extent in the Northern Hemisphere is in general agreement with observational data except for summer where the extent is somewhat underestimated. In the Southern Hemisphere, large negative biases are found in the simulated sea-ice extent. This is partly related to problems with the mixed layer parametrization, causing the mixed layer in the Southern Ocean to be too deep, which in turn makes it hard to maintain a realistic sea-ice cover here. However, despite some problematic issues, the pre-industrial control simulation presented here should still be appropriate for climate change studies requiring multi-century simulations.
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ANDERSON, M. E., and MICHAEL M. MINCARONE. "Studies on the Zoarcidae (Teleostei: Perciformes) of the southern hemisphere. IX. A new species of Pachycara from the southwestern Atlantic." Zootaxa 1177, no. 1 (2006): 21. http://dx.doi.org/10.11646/zootaxa.1177.1.2.
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A new species of deep-sea eelpout, Pachycara alepidotum, is described from four specimens, 199– 282 mm SL, collected in the upper bathyal zone off Rio Grande do Sul state, southern Brazil, and is the first record of the genus in the southwestern Atlantic. It is characterized by its lack of scales and ventral lateral line, few caudal vertebrae and only 1–2 rakers on the upper limb of the first gill arch. The largest specimen is an adult female.
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Wang, Xiaoli, Peter H. Stone, and Jochem Marotzke. "Global Thermohaline Circulation. Part II: Sensitivity with Interactive Atmospheric Transports." Journal of Climate 12, no. 1 (1999): 83–91. http://dx.doi.org/10.1175/1520-0442-12.1.83.
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Abstract A hybrid coupled ocean–atmosphere model is used to investigate the stability of the thermohaline circulation (THC) to an increase in the surface freshwater forcing in the presence of interactive meridional transports in the atmosphere. The ocean component is the idealized global general circulation model used in Part I. The atmospheric model assumes fixed latitudinal structure of the heat and moisture transports, and the amplitudes are calculated separately for each hemisphere from the large-scale sea surface temperature (SST) and SST gradient, using parameterizations based on baroclinic stability theory. The ocean–atmosphere heat and freshwater exchanges are calculated as residuals of the steady-state atmospheric budgets. Owing to the ocean component’s weak heat transport, the model has too strong a meridional SST gradient when driven with observed atmospheric meridional transports. When the latter are made interactive, the conveyor belt circulation collapses. A flux adjustment is introduced in which the efficiency of the atmospheric transports is lowered to match the too low efficiency of the ocean component. The feedbacks between the THC and both the atmospheric heat and moisture transports are positive, whether atmospheric transports are interactive in the Northern Hemisphere, the Southern Hemisphere, or both. However, the feedbacks operate differently in the Northern and Southern Hemispheres, because the Pacific THC dominates in the Southern Hemisphere, and deep water formation in the two hemispheres is negatively correlated. The feedbacks in the two hemispheres do not necessarily reinforce each other because they have opposite effects on low-latitude temperatures. The model is qualitatively similar in stability to one with conventional “additive” flux adjustment, but quantitatively more stable.
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Malyutina, M. V. "Storthyngurella, new genus of Munnopsidae (Crustacea: Isopoda), with descriptions of three new species from deep–sea basins of the Southern Hemisphere." Memoirs of Museum Victoria 57, no. 2 (1999): 267–85. http://dx.doi.org/10.24199/j.mmv.1999.57.16.
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van de Wal, R. S. W., B. de Boer, L. Lourens, P. Köhler, and R. Bintanja. "Continuous and self-consistent CO<sub>2</sub> and climate records over the past 20 Myrs." Climate of the Past Discussions 7, no. 1 (2011): 437–61. http://dx.doi.org/10.5194/cpd-7-437-2011.
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Abstract. The gradual cooling of the climate during the Cenozoic has generally been attributed to a decrease in CO2 concentration in the atmosphere. The lack of transient climate models and in particular the lack of high-resolution proxy records of CO2, beyond the ice-core record prohibit however a full understanding of the inception of the Northern Hemisphere glaciation, as well as the mid-Pleistocene transition. Here we elaborate on an inverse modeling technique to reconstruct a continuous high-resolution CO2 record over the past 20 Ma, by decomposing the global deep-sea benthic δ18O record into a mutually consistent temperature and sea-level record, using a set of 1-D models of the major Northern and Southern Hemisphere ice sheets. We subsequently compared the modeled temperature record to ice core and proxy-derived CO2 data to reconstruct a continuous CO2 record over the past 20 Myrs. Results show a gradual decline from 450 ppmv around 15 Myrs ago to 280 ppmv for pre-industrial conditions, coinciding with a gradual cooling of the Northern Hemisphere land temperatures by approximately 12 K, whereas there is no long-term sea-level variation caused by ice-volume changes between 13 to 3 Myrs ago. We find no evidence for a change in climate sensitivity other than the expected decrease following from saturation of the absorption bands for CO2. The reconstructed CO2 record shows that the Northern Hemisphere glaciation starts once the average CO2 concentration drops below 265 ppmv after a period of strong decrease in CO2. Finally it might be noted that we observe only a small long-term change (23 ppmv) for CO2 during the mid-Pleistocene transition.
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Brandt, Angelika, Magdalena Błażewicz-Paszkowycz, Roger Bamber, et al. "Are there widespread peracarid species in the deep sea (Crustacea: Malacostraca)?" Polish Polar Research 33, no. 2 (2012): 139–62. http://dx.doi.org/10.2478/v10183-012-0012-5.
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Are there widespread peracarid species in the deep sea (Crustacea: Malacostraca)?The global zoogeographic distribution of the most widespread peracarid species occurring in three or more ocean basins below 2000 m is analysed. Basing on the published data we investigated 45 peracarid species, which have a most widespread distribution and most likely are cosmopolitan. Thirty-three species have a wide distribution in the Northern Hemisphere. Most species occur in the North Atlantic, however, 16 of these species occur also in the North Pacific, a more limited number of species occurs in the South Atlantic or South Pacific The Southern Ocean displays some special zoogeographic features and 22 widespread species occur there below 2000 m, including highly eurybathic ones. In total, 11 of the analysed species occur in all oceans.Eucopia australis(Lophogastrida),Munneurycope murrayi(Isopoda) andEurythenes gryllus(Amphipoda) are the species with the widest distributions. Other peracarids occurring in all oceans are: the isopodsParamunnopsis oceanicaandEurycope sarsi, the mysidCaesaromysis hispidathe lophogastridEucopia unguiculata, the amphipodMesopleustes abyssorumand the tanaidsExspina typica, Paranarthura insignisandPseudotanais nordenskioldi. No cumacean species has been reported with an ocean-wide distribution butCampylaspis glabraoccurs in the Atlantic, Indian and Pacific oceans. Among plenty of rare species in each order there are only few species with wide distribution records. There is evidence from molecular genetic studies that some of the widespread peracarids represent several cryptic species, however, some,e.g. Eucopia australis, seem to be truly cosmopolitan species. Geography of sampling is biasing our view of biogeography. The history and quality of taxonomic work as well as the reliability of geo- graphic records (quality control of large databases) limits our investigations of widespread or cosmopolitan species as much as the limited knowledge of variation within most species causes difficulties in defining morpho-species with certainty.