Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 89 for “"LGM"”.
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Atlantic Ocean circulation at the Last Glacial Maximum : inferences from data and models
… the Atlantic Ocean at the Last Glacial Maximum (LGM, 18-21 thousand years before present). Relative to the pre-industrial climate, LGM atmospheric CO2 concentrations were about 90 ppm lower, ice sheets were much more extensive, and many regions experienced significantly colder temperatures. In …
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Atlantic Ocean circulation at the last glacial maximum : inferences from data and models
… the Atlantic Ocean at the Last Glacial Maximum (LGM, 18-21 thousand years before present). Relative to the pre-industrial climate, LGM atmospheric CO₂ concentrations were about 90 ppm lower, ice sheets were much more extensive, and many regions experienced significantly colder temperatures. In …
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Using the fossil charcoal and pollen records from Elands Bay Cave and Boomplaas Cave, South Africa, to reconstruct variability in local hydroclimate and seasonality
… Ma, but particularly the Last Glacial Maximum (LGM). An equator-wards shift in the SH Westerlies has long been used to account for increased precipitation in SA during the LGM. While this narrative is challenged by a few records from the Southern Cape, which suggest aridity during the LGM, it …
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Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data
… source water production. Last glacial maximum (LGM) Cd/Ca and δ13C data indicate a nutrient-depleted intermediate-depth water mass. In the mid-depth western South Atlantic, a simple conversion of LGM δ13C data suggests significantly less nutrient enrichment than LGM Cd/Ca ratios, but Cd/Ca and …
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Western South Atlantic holocene and glacial deepwater hydrography derived from benthic foraminiferal Cd/Ca and stable carbon isotope data
… source water production. Last glacial maximum (LGM) Cd/Ca and 813C data indicate a nutrient-depleted intermediate-depth water mass. In the mid-depth western South Atlantic, a simple conversion of LGM 813C data suggests significantly less nutrient enrichment than LGM Cd/Ca ratios, but Cd/Ca and …
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Climatic factors influencing Last Glacial Maximum and modern glacial conditions in the tropical and subtropical Andes
… Model results show average Last Glacial Maximum (LGM) equilibrium line altitude (ELA) depressions to be approximately 600 m in the tropics and 800 m in the subtropics, consistent with studies that suggest the subtropical Andes were glaciated at LGM. While previous studies have found that the …
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What do paleo-geochemical tracers tell us about the deep ocean circulation during the last ice age?
… further north during the Last Glacial Maximum (LGM) (Boyle and Keigwin, 1982; 1987; Duplessy et al., 1988). The evidence for this interpretation is re-examined in this work, with an emphasis on the quantitative analysis of the paleo-data. An end-member analysis of the δ13C data indicates a …
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Species response to shifting and variable climates
… taxa persisted through the Last Glacial Maximum (LGM) in Alaska and adjacent Canada. In part, my dissertation investigated the spatial patterns of glacial persistence and postglacial colonization of an alder (Alnus) species complex (n = 3 taxa) from this vast region. Using high-throughput DNA …
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Inferring ocean circulation during the Last Glacial Maximum and last deglaciation using data and models
Since the Last Glacial Maximum (LGM, ~ 20,000 years ago) air temperatures warmed, sea level rose roughly 130 meters, and atmospheric concentrations of carbon dioxide increased. This thesis combines global models and paleoceanographic observations to constrain the ocean’s role in storing and …
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Inferring ocean circulation during the last glacial maximum and last deglaciation using data and models
Since the Last Glacial Maximum (LGM, ~ 20,000 years ago) air temperatures warmed, sea level rose roughly 130 meters, and atmospheric concentrations of carbon dioxide increased. This thesis combines global models and paleoceanographic observations to constrain the ocean's role in storing and …
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Submarine Geomorphology of the Continental Shelves of Southeast and Southwest Greenland from Olex Data
… Sheet during and after the Last Glacial Maximum (LGM), this study used geophysical bathymetric data to investigate the geomorphology of the continental margins of Southern Greenland. In particular, Olex data, which consist of multiple single-beam echo-sounder lines, were utilised. Turbidity …
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Zinc and cadmium in benthic foraminifera as tracers of ocean paleochemistry
… in nutrients during the last glacial maximum (LGM). A high-resolution Cd/Ca record from 965 m water depth suggests that Glacial North Atlantic Intermediate Water formation was strong during the LGM, weakened during the deglaciation, and strengthened again during the Younger Dryas cold period. …
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Zinc and cadmium in benthic foraminifera as tracers of ocean paleochemistry
… in nutrients during the last glacial maximum (LGM). A high-resolution Cd/Ca record from 965 m water depth suggests that Glacial North Atlantic Intermediate Water formation was strong during the LGM, weakened during the deglaciation, and strengthened again during the Younger Dryas cold period. …
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Think global, act local when estimating a sparse precision matrix
… approaches like GLASSO. This thesis introduces LGM, a new algorithm for the estimation of sparse high dimensional precision matrices. Using the framework of probabilistic graphical models, the algorithm performs robust covariance estimation to generate potentials for small cliques and fuses the …
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Glacial-interglacial variations of the water masses in the southeast Atlantic Ocean derived from foraminiferal neodymium isotope ratios
… believed that, during the Last Glacial Maximum (LGM), the transport of North Atlantic Deep Water (NADW) to the southeast Atlantic Ocean was reduced. A popular method to trace these ambient changes is the stable isotope systematics of neodymium (given as εNd). In this study εNd data were measured …
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Constraining uncertainty in climate sensitivity : an ensemble simulation approach based on glacial climate
… and proxy-data from the Last Glacial Maximum (LGM). Our analyses are based on an ensemble of fully-coupled simulations, that were realized with a climate model of intermediate complexity (CLIMBER-2). These model versions cover a broad range of different climate sensitivities, ranging from 1.3 …
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The demography of Red Sea reef fishes since the Last Glacial Maximum
… experienced during the Last Glacial Maximum (LGM) was not as small as was expected, highlighting the importance of coral reef habitat and refugia. Studying the impact of the LGM on Dascyllus marginatus, a species with a restricted range in the Indian Ocean, enabled me to use this study design …
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Physical activity referral schemes: adherence and physical activity behaviour change
… for the latest PARS called Let‟s Get Moving (LGM). There was a significantly weak association between IPAQ and GPPAQ. Hence, the GPPAQ is only recommended to be used as a PA screening tool and not for evaluating PA levels for PARS research studies. The final study was based on the new LGM …
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Constraining circulation changes through the last deglaciation with deep-sea coral radiocarbon and sedimentary 231Pa/230Th
… Southern Ocean during the last glacial maximum (LGM) that disappeared during the start of the deglaciation as atmospheric CO2 began to rise during Heinrich Stadial 1 (H1). Considering these data and using a simple mass budget calculation, I show that the drop in atmospheric radiocarbon activity …
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