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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

El Niño-Southern Oscillation variability during the Little Ice Age and medieval climate anomaly reconstructed from fossil coral geochemistry and pseudoproxy analysis

Hereid, Kelly Ann 26 February 2013 (has links)
The El Niño-Southern Oscillation (ENSO) dominates global interannual climate variability. However, the imprint of anthropogenic climate change hinders understanding of natural ENSO variability. Model predictions of the response of future ENSO variability to anthropogenic forcing are highly uncertain. A better understanding of how ENSO operates during different mean climate states may improve predictions of its future behavior. This study develops a technique to quantify the response of tropical Pacific sea surface temperature and salinity to ENSO variations. This analysis defines expected regional relationships between ENSO forcing and the tropical Pacific climate response. For example, the western tropical Pacific records El Niño events with greater skill than La Niña events; whereas the oceans near the South Pacific Convergence Zone (SPCZ) preferentially record La Niña events. This baseline understanding of regional skill calibrates interpretations of both modern and pre-instrumental coral geochemical climate proxy records. A suite of monthly resolved 18O variations in a fossil corals (Porites spp.) from the tropical western Pacific (Papua New Guinea) and the SPCZ (Vanuatu) are used to develop case studies of ENSO variability under external forcing conditions that differ from the modern climate. A record from Misima, Papua New Guinea (1411-1644 CE) spans a period of reduced solar forcing that coincides with the initiation of the Little Ice Age. This record indicates that the surface ocean in this region experienced a small change in hydrologic balance with no change in temperature, extended periods of quiescence in El Niño activity, reduced mean El Niño event amplitudes, and fewer large amplitude El Niño events relative to signals captured in regional modern records. Several multidecadal (~30-50 year) coral records from Tasmaloum, Vanuatu during the Medieval Climate Anomaly (~900-1300 CE), a period of increased solar forcing, depict ENSO variability that is generally lower than modern times. However, these records often cannot be distinguished from 20th century ENSO variability due to ENSO variability uncertainty associated with record lengths. Neither record can be tied to concurrent changes in solar or volcanic forcing, calling into question the paradigm of ENSO variability being predominantly mediated by external forcing changes on multidecadal time scales. / text
72

Interannual thermal-regime variability of two lakes in British Columbia, Canada : implications for climate change

Wijtkamp, Peter James 20 December 2011 (has links)
This study examines the inter-annual variability of the thermal regime of two lakes, Quesnel Lake a very long residence-time lake and Kamloops Lake a short residence-time river-dominated lake. The changes are compared to local climate conditions as well as inter-annual variability associated with the El Nino Southern Oscillation (ENSO). Observations include that higher air temperatures in El Nino years are associated with higher surface water temperature, as well as earlier onset and longer duration of summer stratification. Observed lake heat content calculated from temperature profiles balanced well with the sum of heat fluxes calculated from meteorological data. Results indicate differences in the importance of heat flux components to the heat budgets of these lakes especially the river throughflow in Kamloops Lake. Since climate projections indicate more warming for this region the different potential impacts to the thermal regime of these lakes should be considered in environmental and resource management decisions.
73

Um estudo das anomalias de precipitação no Panamá associadas aos episódios El Niño/Oscilação do Sul dos anos 1969, 1972, 1976 e 1982. / A study of precipitation anomalies in Panama associated with the El Niño / Southern Oscillation episodes of 1969, 1972, 1976 and 1982.

MARTÍNEZ, Alberto Smith. 27 September 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-27T14:34:11Z No. of bitstreams: 1 ALBERTO SMITH MARTÍNEZ - DISSERTAÇÃO PPGMet 1990..pdf: 13526465 bytes, checksum: 4046ef5126ade3f308837da19a9332af (MD5) / Made available in DSpace on 2018-09-27T14:34:11Z (GMT). No. of bitstreams: 1 ALBERTO SMITH MARTÍNEZ - DISSERTAÇÃO PPGMet 1990..pdf: 13526465 bytes, checksum: 4046ef5126ade3f308837da19a9332af (MD5) Previous issue date: 1990-12-19 / Capes / O re 1 ac ionamrnt o entre o fenómeno El Niño/Oscilação do Sul (FNSO) e a precipitação no Panamá foi estudado para o período de 1967 a 1986 mediante a utilização de dados de totais mensais e de anomalias de precipitação, cartas de anomalias de precipitação, dados e composições da anomalia da temperatura da superfície do mar (TSM) na costa do Peru e proximidades, e por uma análise estatística simples. Os resultados indicam que durante os anos ENSO a precipitação ap resen t a-se, em média, IP, 7'/. abaixo do normal. Porém, há regiões com anomalias negativas de até 50% devido á considerável variabilidade espacial de precipitação. A estação chuvosa (abri1-novembro) é interrompida por desvios negativos predominantes nos meses de julho e agosto ocasionando uma significativa redução de precipitação durante a estação. Correlações efetuadas indicam uma estreita relação negativa entre a precipitação P O sinal do FNSO, com os mais altos Índices para os atrasos ("lag") de 3 meses, sugerindo que a precipitação total de um mês pode spr prevista com antecedência através dos dados da TSM. Mediante os resultados obtidos neste estudo e pelas descrições do comportamento do sistema oceano-atmos fera durante o ENSO apresentadas por vários pesquisadores conclue-se que é o deslocamento anómalo da 7ona de Convergência Intertropical (ITCZ), principal fator de precipitação no Panamá, o maior responsável pelas anomalias de precipitação apresentadas no pais durante o evento. / Thp relationship bptwppn thp El Nino/Southern Oscillation (ENSO) phenomenon and Panamá precipitation was studied for the period 1967-1986 using precipitation composites and total means, deviation maps of precipitation, sea surface temperature anomalies data from Peru coast and proximities and a simple statistic analysis. Results indicate that during the ENSO years the precipitation show, on the average, 12.7% below normal. However a considerable precipitation variability in space exhibit regions with negatives anomalies up to 5<Ò'Á. The rainy season (AprilNovember) is interrupted by negatives deviations prevailing on the months of July and August causing a significative reduction in precipitation during the season. Correlations indicates a close negative relation between precipitation and the ENSO signal, introducing the most higher indexes for delay ("lag") of 3 months and indicating that a month total precipitation can be expected in advance with the TSM data. With the results on this study and descriptions of the ocean-atmosphere system behaviour during the ENSO presented by various researchers, we may conclude that the anomaly shift of the Inter-Tropical Convergence Zone (ITCZ), mainly factor of precipitation on Panamá, is the major responsible for the precipitation anomalies presented in the country during the event.
74

Tropical Pacific climate variability over the last 6000 years as recorded in Bainbridge Crater Lake, Galápagos

Thompson, Diane M., Conroy, Jessica L., Collins, Aaron, Hlohowskyj, Stephan R., Overpeck, Jonathan T., Riedinger-Whitmore, Melanie, Cole, Julia E., Bush, Mark B., Whitney, H., Corley, Timothy L., Kannan, Miriam Steinitz 08 1900 (has links)
Finely laminated sediments within Bainbridge Crater Lake, Galapagos, provide a record of El Nino-Southern Oscillation (ENSO) events over the Holocene. Despite the importance of this sediment record, hypotheses for how climate variability is preserved in the lake sediments have not been tested. Here we present results of long-term monitoring of the local climate and limnology and a revised interpretation of the sediment record. Brown-green, organic-rich, siliciclastic laminae reflect warm, wet conditions typical of El Nino events, whereas carbonate and gypsum precipitate during cool, dry La Nina events and persistent dry periods, respectively. Applying this new interpretation, we find that ENSO events of both phases were generally less frequent during the mid-Holocene (similar to 6100-4000 calendar years B.P.) relative to the last similar to 1500 calendar years. Abundant carbonate laminations between 3500 and 3000 calendar years B.P. imply that conditions in the Galapagos region were cool and dry during this period when the tropical Pacific E-W sea surface temperature (SST) gradient likely strengthened. The frequency of El Nino and La Nina events then intensified dramatically around 1750-2000 calendar years B.P., consistent with a weaker SST gradient and an increased frequency of ENSO events in other regional records. This strong interannual variability persisted until similar to 700 calendar years B.P., when ENSO-related variability at the lake decreased as the SST gradient strengthened. Persistent, dry conditions then dominated between 300 and 50 calendar years B.P. (A.D. 1650-1900, +/- similar to 100 years), whereas wetter conditions and frequent El Nino events dominated in the most recent century. Plain Language Summary Sediments accumulating at the bottom of Bainbridge Crater Lake have provided a record of Galapagos climate and the frequency of El Nino events over the past similar to 6000 years. Motivated by the importance of this lake for our understanding of climate in the tropical Pacific Ocean, we have been monitoring the link between climate, lake conditions, and the physical and chemical properties of the lake sediments since 2009. Based on this long-term monitoring, we find that the Bainbridge sediment record preserves both El Nino and La Nina events. This makes Bainbridge a particularly valuable archive of past climate, as most sediment-based records typically preserve only one or the other key phase of tropical Pacific climate.
75

Implications of heat stress and local human disturbance on early life stage corals

Tietjen, Kristina 28 January 2020 (has links)
Coral reef recovery following a disturbance relies heavily on the restoration of coral cover, via growth of existing colonies and the successful recruitment of new corals. In well-connected reef networks, recruits may be sourced from neighboring reefs. In contrast, coral recruitment on geographically isolated reefs is reliant on adult corals at that location, which may limit recovery rates following mass coral mortality events. Such mortality events are increasingly caused by climate change induced temperature anomalies, which are overlaid on the local chronic human disturbances that already affect most of the world’s coral reefs. In this thesis, I exploit a natural ecosystem-scale experiment to examine how multiple anthropogenic stressors impact densities of coral recruits and small corals (e.g., juveniles; 5 cm) on Kiritimati (Christmas Island, Republic of Kiribati), an isolated atoll in the central equatorial Pacific Ocean. Specifically, I used benthic survey videos from before, during, and one year following the 2015-2016 El Niño and coral settlement tiles deployed during the three years after the event at 22 sites across the island, to quantify small corals and coral recruits, respectively. Local chronic stress negatively impacted small corals, with densities 47% lower at sites exposed to very high levels of chronic stress prior to the heat stress. The El Niño further resulted in a 56% loss of small corals, particularly for competitive coral species. Following the event, stress tolerant small corals rebounded to pre-El Niño densities within a year, whereas competitive and small corals overall had non-significant increases. I also quantified a low recruitment rate of 8.31 recruits m-2 per year (± 1.9 SE) during the three years following the El Niño compared to previous studies around the Pacific; recruits were genetically identified as primarily belonging to the stress tolerant family Agariciidae and the competitive genus Pocillopora. Local human disturbance also impacted coral recruitment with densities significantly lower at those with the greatest local chronic disturbance, together suggesting that local disturbance impedes post-settlement survival of recruits and the resilience of young corals during acute stress events. With increased net primary productivity, densities of both small corals and recruits (non-significant) also increased, which could reflect the positive influence of coral heterotrophic nutrition supplements during and after stress events, increasing survivability. Despite very low overall coral recruitment, all island regions did have some recruits, but Vaskess Bay (a bay region on the southern part of the island) had the highest densities. Overall these results indicate the negative consequences combined chronic and acute stressors can have on coral recruits, small corals, and accompanying coral resilience. When viewed together, this work suggests how the resilience is compromised by chronic stressors on Kiritimati and that the recovery trajectory may be variable across the disturbance gradient. Thus, local reef management may provide an avenue for enhancing recovery rates as acute temperature anomalies increase in frequency under our current climate trajectory. / Graduate / 2021-01-14
76

La respuesta del voluntariado corporativo en la emergencia de El Niño costero 2017 en Lima, Perú

Ramirez Farias, Carmen Adriana 09 September 2019 (has links)
La comunicación estratégica acerca nuevas entradas de análisis para incrementar el valor del voluntariado corporativo en la Gestión de Riesgo de Desastres (GRD). La memoria profesional propone analizar la respuesta del voluntariado corporativo en la emergencia de El Niño Costero suscitado en el año 2017 en Lima, Perú; evento del cual la autora fue partícipe dentro de su ejercicio profesional en Voluntarios ONU Perú. La metodología empleada propone un estudio de caso y subraya 3 momentos de análisis: antes, durante y después de la emergencia. Incluye entrevistas y grupos focales aplicados a gestoras de voluntariado corporativo de Empresas que Inspiran: red de empresas peruanas que promueven voluntariado corporativo para el desarrollo sostenible, así como a especialistas en GRD. Reflexiona sobre el posicionamiento del voluntariado corporativo de cara a los actores responsables de la respuesta establecidos en el Plan Nacional de GRD, así como la importancia del auto reconocimiento de capacidades del voluntariado corporativo para dar soporte oportuno y eficiente a la respuesta en contextos de emergencia y en otras etapas de la GRD. Analiza la influencia que el voluntariado corporativo genera en grupos de interés priorizados, que, a su vez, puede repercutir en factores reputacionales. El estudio se torna relevante pues pone de manifiesto el valor agregado de las profesionales en comunicación para el desarrollo para establecer, sobre la base de evidencia, estrategias para hacer más visibles, articuladas y de impacto las intervenciones en voluntariado corporativo en contextos de emergencia y en la promoción de comunidades más resilientes.
77

The Impact of El-Niño and La-Niña on the Pre-Monsoon Convective Systems over Eastern India

Kumar Sahu, Rajesh, Choudhury, Goutam, Vissa, Naresh Krishna, Tyagi, Bhishma, Nayak, Sridhara 06 December 2023 (has links)
El-Niño and La-Niña are believed to change the intensity and frequencies of extreme weather events globally. The present study aims to analyse the impact of El-Niño and La-Niña on the lightning activities of cloud systems and their associated precipitation and thermodynamic indices over the Eastern India regions (Odisha, Jharkhand, and West Bengal) during the pre-monsoon season (March–May). Eastern India receives catastrophic thunderstorm events during the pre-monsoon season. The results suggest that the number of lightning flashes was higher in the El-Niño years than in the La-Niña periods, which helps convective activities to be developed over the study region. The precipitation variations showed similar patterns during El-Niño and La-Niña periods, but the magnitudes were higher in the latter. Results from the analysis of thermodynamic indices show that, during the La-Niña phase, the convective available potential energy (CAPE), convective inhibition (CIN), severe weather threat index (SWEAT), humidity index (HI), and total totals index (TTI) values increased, while the cross total index (CTI) and K index (KI) decreased. In contrast, the vertical total index (VTI) and Boyden index (BI) values showed less significant changes in both El-Niño and La-Niña periods. The anomalies of flash rate densities over most parts of our domain were positive during the El-Niño years and negative during the La-Niña years. Precipitation anomalies had a higher positive magnitude during the La-Niña phase, but had spatial variability similar to the El-Niño phase. The anomalies of most of the thermodynamic indices also showed noticeable differences between El-Niño and La-Niña periods, except for the HI index. El-Niño periods showed higher lightning and increased values of associated thermodynamic indices over eastern India, indicating more pronounced convective systems.
78

Diseño de un proceso computacional basado en técnicas de minería de datos para el análisis del fenómeno de "El Niño"

Díaz Barriga, Oscar Antonio 19 January 2018 (has links)
El Perú es afectado recurrentemente por el fenómeno El Niño, el cual es un fenómeno climático que consiste en el aumento de la temperatura del mar en el Pacifico Ecuatorial. Este a su vez forma parte del ENSO (El Niño - Oscilación del Sur) que tiene un periodo de actuación de 2 a 7 años, con una fase cálida conocida como El Niño y una fase fría, La Niña. En la actualidad mediante un juicio experto se analizan las diversas fuentes de datos heterogéneas para poder encontrar posibles correlaciones útiles entre ellos. En el presente trabajo se propone un proceso computacional basado en técnicas de minería de datos que permita determinar la existencia de correlaciones espacio-temporales en relación a la temperatura superficial del mar y las variables meteorológicas pertenecientes a las regiones de la costa norte del Perú, en el periodo 2015 al 2016, último intervalo de tiempo en el que se presentó El Nino. Para esto se utiliza una metodología basada en KDD (Knowledge Discovery in Database), la cual está conformada por una serie de pasos como: la recolección de diferentes fuentes de datos, la integración en una base de datos explotable, limpieza y pretratamiento de los datos, creación de escenarios que permitan validar las posibles correlaciones, extracción de patrones mediante la librería SPMF y finalmente una propuesta de visualización, de los patrones encontrados, que permita comprender mejor el fenómeno. Los resultados obtenidos muestran la existencia de correlaciones espaciotemporales en las regiones del norte del Perú principalmente entre la temperatura de la superficie del mar y el caudal de los ríos de la costa, siendo estas correlaciones validadas por un experto miembro del IGP. / Tesis
79

Programa “Mi bebé, yo y la lactancia” para optimizar el nivel informativo sobre lactancia materna y desarrollo orofacial en el neonato en las madres gestantes del centro psicoprofiláctico “Nueve Lunas”

Lucar Olivera, Yanina Viviana, Ratto Bashi, Daniella Pierinna 20 January 2020 (has links)
El objetivo de la presente investigación es incrementar el nivel de información acerca del desarrollo orofacial y la lactancia materna en el neonato a través del programa “Mi bebé, yo y la lactancia” en madres gestantes del Centro Psicoprofiláctico “Nueve Lunas”. Siendo un estudio de tipo cuantitativo con un diseño pre experimental con pre y post test, para lo cual la muestra seleccionada de manera intencional, estuvo conformada por 16 madres gestantes. Este grupo fue evaluado a través de un cuestionario de 20 preguntas en función al desarrollo orofacial y lactancia en el neonato, validado por especialistas en la modalidad de juicio de expertos. El grupo de madres asistentes al Centro Psicoprofiláctico “Nueve Lunas” evidenció un desconocimiento de la importancia de la lactancia materna para el desarrollo orofacial en sus bebés. Gracias al programa elaborado, “Mi bebé, yo y la lactancia”, se pudieron suplir dudas y brindar información acerca del tema en mención. Además de saber que la lactancia es la fuente básica de muchos beneficios tanto para el bebé como para la madre, esta también, ayuda al desarrollo muscular y fisiológico de los órganos estomatognáticos, ya que si se realiza de forma correcta disminuirá las maloclusiones en su vida futura. Es importante que la difusión de estos programas pueda brindarse en Centros de Salud, Maternidades, Centros de estimulación, entre otros; a fin de evitar futuros hábitos nocivos de succión y anomalías orofaciales, resaltando así, la importancia de la lactancia exclusiva hasta los 6 meses.
80

La psicomotricidad de Aucouturier y las habilidades sociales en niños con Asperger

Marca de la Cerna, Ana Sofía Alexandra 29 January 2021 (has links)
Esta investigación nació del deseo de reivindicar la importancia del desarrollo motor en la formación de habilidades sociales en niños con Asperger y dar a conocer la potencialidad de la psicomotricidad de Aucouturier en el desarrollo social de estos infantes. En cuanto al problema de investigación, este es el siguiente: ¿cómo se desarrollan las habilidades sociales desde el marco del enfoque psicomotor dinámicovivencial en niños del nivel primaria con Asperger? Asimismo, tuvo como principal objetivo el análisis de la importancia de la psicomotricidad de Aucouturier en el desarrollo de habilidades sociales de los niños con Asperger. Los contenidos trabajados son las características personales y situación escolar nacional e internacional de los niños Asperger, las bases conceptuales de la psicomotricidad y los conceptos teóricos de la psicomotricidad dinámico-vivencial. Finalmente, se concluye que el enfoque psicomotor dinámico-vivencial de Aucouturier permite a los niños con síndrome de Asperger explorar una manera diferente a las palabras para expresar sus sentimientos, emociones e ideas y entablar estables vínculos socioafectivos. Además, esta investigación le brinda al docente un herramienta lúdica y vivencial que logra, a través del movimiento, el desarrollo de habilidades sociales en estos niños con el objetivo de brindarles una formación integral que vence su principal limitación: la interacción social.

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