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  • 1
    Publication Date: 2014-12-20
    Description: During the last interglacial period, global temperatures were ~2 degrees C warmer than at present and sea level was 6 to 8 meters higher. Southern Ocean sediments reveal a spike in authigenic uranium 127,000 years ago, within the last interglacial, reflecting decreased oxygenation of deep water by Antarctic Bottom Water (AABW). Unlike ice age reductions in AABW, the interglacial stagnation event appears decoupled from open ocean conditions and may have resulted from coastal freshening due to mass loss from the Antarctic ice sheet. AABW reduction coincided with increased North Atlantic Deep Water (NADW) formation, and the subsequent reinvigoration in AABW coincided with reduced NADW formation. Thus, alternation of deep water formation between the Antarctic and the North Atlantic, believed to characterize ice ages, apparently also occurs in warm climates.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hayes, Christopher T -- Martinez-Garcia, Alfredo -- Hasenfratz, Adam P -- Jaccard, Samuel L -- Hodell, David A -- Sigman, Daniel M -- Haug, Gerald H -- Anderson, Robert F -- New York, N.Y. -- Science. 2014 Dec 19;346(6216):1514-7. doi: 10.1126/science.1256620.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA 02142, USA. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA. cthayes@mit.edu. ; Geological Institute, ETH Zurich, 8092 Zurich, Switzerland. ; Institute of Geological Sciences and Oeschger Centre for Climate Change Research, University of Bern, 3012 Bern, Switzerland. ; Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK. ; Department of Geosciences, Princeton University, Princeton, NJ 08544, USA. ; Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25525246" target="_blank"〉PubMed〈/a〉
    Keywords: Atlantic Ocean ; Climate Change ; *Ice Cover ; Oxygen/analysis ; Salinity ; *Seawater
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2021-05-19
    Description: Dentro de las actividades científicas contempladas en la VII Expedición Ecuatoriana a la Antártida para enero de 1998 en Buque de Investigación de la Armada B/I Orión efectuó un crucero oceanográfico en el Estrecho Branfield. Se efectuaron 14 estaciones oceanográficas hasta 500 metros, se realizaron mediciones de corriente utilizando un perfilador acústico doppler. Tomando como referencia trabajos anteriores en el área en años sin influencia de eventos cálidos se compararon los parámetros físicos. Luego del análisis se concluye que el evento ENSO 97-98 tuvo repercusiones evidentes en el área de estudio manifestada en dos aspectos básicos: El incremento de la temperatura y la disminución de la salinidad a nivel superficial. Esta variación habría generado un debilitamiento en la circulación termohalina desde el área Antártica que podría haber afectado la circulación hacia el continente americano y correctamente la Corriente de Humboldt que se mostró durante todo el evento ENSO 97-98, muy debilitada y replegada hacia el sur. Otro efecto evidenciado en el fortalecimiento de las corrientes en toda la vertical hasta los 70 m aunque los patrones de circulación se mantuvieron muy similares a estudios efectuados en años relativamente normales. Las alteraciones térmicas podrían asociarse con la convergencia de aire caliente desde los trópicos y la redistribución anómala de calor hacia latitudes Antárticas en tanto que las variaciones de salinidad estarían relacionadas con deshielos más intenso en el área de estudio. Las masas de agua encontradas son concordantes con estudios en años anteriores, definiendo claramente la influencia poco salina y caliente del mar de Bellingshousen frente a la mayoritaria presencia de aguas más salinas y más fría, en casi todo el estrecho. La metodología uilizada en la medición de corrientes no permite establecer el transporte de características desde el Mar de Weddell sugiriendo más bien una notable influencia en el estrecho de aguas provenientes del Paso Drake.
    Description: Withinthe scientific activities planned in the VII Ecuadorian Expedition to the Antarctica in january of 1998 the Research vessel of the Navy B/I Orión effected an oceanographic cruise in the Bransfield Strait. 14 stations were made to 500 meters depth, where also it was carried out measurements of current using an accoustic doppler current profiler. Previous work in the area of years without influence of warm events was taken as reference and physical parameters were compared. Analyses concluded that the ENSO event 97-98 had evident repercussions in the study area manifested in two basic looks: The increments of the temperature and the decreasing of the superficial salinity. This variation would have generated a weakening on thermohaline circulation from the Antarctic area that could have affected the circulation toward the american continent and concretely in features of the Humboldt Current that was shown during all ENSO 97-98 event, very weakened and displaced toward the south. Another evidenced effect is the strengthening of currents in the vertical even the 70 m. Although the patrons of circulation stay very similar to studies effected in years relatively normal. The thermal alterations could associate with the convergence of warm air from the tropics and the anomalous redistribution of heat toward Antarctic latitudes. Variations of salinity would be related with more intense melting in the area of study. The water masses detected are coincident with studies in previous years, defining the not very saline and warm influence of Bellingshousen Sea opposite to majority influence of more saline water and more cold in almost all strait. The methodology used in determining of current doesn't allow to establish the transport of characteristics from the sea of Weddell suggesting a more notable influence in the strait of waters come from the Drak Pass.
    Description: Published
    Keywords: Salinity ; Variability ; Thermohaline circulation ; Salinity ; Water masses ; El Nino phenomena ; Cruises ; Research vessels
    Repository Name: AquaDocs
    Type: Journal Contribution , Non-Refereed , Article
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