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Classificação de sistemas meteorológicos e comparação da precipitação estimada pelo radar e medida pela rede telemétrica na bacia hidrográfica do alto Tietê; Classification of meteorological systems and comparison of radar estimated precipitation to the measured by telemetric network in the high Tietê watershed

SILVA, Fabrício Daniel Dos Santos; PEREIRA FILHO, Augusto José; HALLAK, Ricardo
Fonte: Sociedade Brasileira de Meteorologia Publicador: Sociedade Brasileira de Meteorologia
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
36.8%
Foram analisadas características da precipitação estimada a partir de 145.194 campos de refletividade, de um total de 827 dias entre 1998 e 2003, obtidos do Radar Meteorológico de São Paulo (RSP). Os eventos foram classificados de acordo com intensidades de precipitação; em Convectivos (EC) e Estratiformes (EE). Quanto à morfologia, cinco tipos de sistemas foram identificados; Convecção Isolada (CI), Brisa Marítima (BM), Linhas de Instabilidade (LI), Bandas Dispersas (BD) e Frentes Frias (FF). Eventos convectivos dominam na primavera e verão e estratiformes no outono e inverno. A CI e a BM tiveram maiores picos de atuação entre outubro e março enquanto as FF de abril a setembro. BD atuam durante todo o ano e as LI só não foram observadas nos meses de junho e julho. Uma comparação pontual entre a precipitação medida pela telemetria e estimada com o radar foi realizada e, mostrou haver, na maioria dos casos, um viés positivo do RSP, para acumulações de 10, 30 e 60 minutos. Com o objetivo de integrar as estimativas de precipitação do radar com as medidas da rede telemétrica, por meio de uma análise objetiva estatística, foram obtidas dos campos de precipitação do radar as estruturas das correlações espaciais em função da distância para acumulações de chuva de 15...

Coagulação/precipitação de efluentes de reator anaeróbio de leito expandido e de sistema de lodo ativado precedido de reator UASB, com remoção de partículas por sedimentação ou flotação; Coagulation/precipitation of effluents from anaerobic expanded bed reactor and activated sludge system preceded by UASB reactor, with particle removal by sedimentation or flotation

Santos, Hélio Rodrigues dos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 08/06/2006 PT
Relevância na Pesquisa
36.8%
Os reatores anaeróbios de concepção mais moderna (e.g., UASB e RALEx) possibilitam a remoção de 65 a 75% de matéria orgânica do esgoto sanitário, com custos de implantação e operação relativamente baixos, em comparação com os processos aeróbios convencionais. Entretanto, esses reatores geralmente são pouco eficientes na remoção de nutrientes e seus efluentes podem apresentar concentrações relativamente elevadas de material orgânico e de sólidos suspensos. Para melhorar a qualidade dos efluentes desses reatores, algumas configurações de pós-tratamento têm sido empregadas no Brasil, dentre as quais os sistemas de lodo ativado e a coagulação/precipitação com sais metálicos, geralmente seguida de flotação por ar dissolvido. Nesta pesquisa, foi avaliada a aplicabilidade da coagulação/precipitação com cloreto férrico, a partir de testes em unidades de coagulação em escala de bancada (jar test e flotateste), para três sistemas de pós-tratamento de efluentes de reatores anaeróbios, a saber: coagulação/precipitação do efluente de um reator anaeróbio (RALEx); co-precipitação em um sistema de lodo ativado; e pós-precipitação do efluente do sistema de lodo ativado. Cada um desses sistemas foi testado com separação de sólidos por sedimentação ou por flotação por ar dissolvido...

O oceano atlântico e a precipitação no estado de São Paulo; South atlantic ocean and precipitation in São Paulo state

Luz, Giovana
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/10/2010 PT
Relevância na Pesquisa
36.77%
O objetivo deste trabalho é investigar a relação entre a Temperatura da Superfície do Mar (TSM) no Oceano Atlântico Sul (OAS) e a precipitação no estado de São Paulo. Para tanto, adotaram-se as escalas mensal e sazonal. A técnica estatística multivariada, chamada Análise de Componentes Principais (ACP, ou EOF em inglês) foi aplicada para definir as áreas homogêneas do oceano (de 'A' a 'L') e as subregiões do continente (de 1 a 7). Além da definição das áreas e sub-regiões, a ACP identificou muito bem os padrões espaciais da precipitação e da TSM em todas as escalas adotadas: mensal contínua, mensal descontínua e sazonal. Na ACP da série temporal sazonal de verão, o primeiro e o segundo modos da precipitação evidenciam a distribuição espacial típica de verão (zonal) para o estado de São Paulo, e a variância explicada por esses dois modos juntos é de 59,79% do total. Esta distribuição espacial já havia sido observada nas análises iniciais a partir das médias sazonais da precipitação, padrão que se explica pelos fluxos de umidade que, nesta estação, devido ao sistema de monções da América do Sul, movem-se mais intensamente em direção ao continente. Já na ACP da série temporal sazonal de inverno...

Avaliação do potencial hidrológico dos nevoeiros e da precipitação oculta em ambiente de Floresta Ombrófila Densa Montana na Serra do Mar, Cunha, SP; Evaluation of the hydrological potential of fog and of occult precipitation in Montane Dense Ombrophilous Forest environment in Serra do Mar, Cunha, Brazil

Arcova, Francisco Carlos Soriano
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 29/11/2013 PT
Relevância na Pesquisa
36.77%
Entre outubro de 2009 e dezembro de 2012, foi realizado estudo no Laboratório de Hidrologia Florestal Walter Emmerich (L.H.F.W.E.), para avaliar o potencial hidrológico dos nevoeiros e a precipitação oculta em ambiente de Floresta Ombrófila Densa Montana, na Serra do Mar, em Cunha, a leste do Estado de São Paulo. Os objetivos específicos da pesquisa foram: 1) avaliar o desempenho de coletores de água de nevoeiro; 2) verificar o potencial de coleta de água de nevoeiro no laboratório; 3) analisar o potencial de coleta de água de nevoeiro em três setores da microbacia experimental D; 4) averiguar a distribuição espacial e temporal de ocorrência dos nevoeiros na microbacia D e 5) estimar a contribuição da precipitação oculta na floresta da microbacia D. Para alcançar os três primeiros objetivos foram usados coletores passivos tipo harpa, nas formas cilíndrica e plana. Para estudar a distribuição de nevoeiros, foram feitas observações diárias de três referências visuais situadas a distâncias conhecidas no interior da microbacia D. O método da medição da precipitação efetiva foi empregado para estimar a precipitação oculta na floresta. Sobre a distribuição espacial e temporal da ocorrência de nevoeiros na microbacia D...

Estimativa da precipitação através de técnicas de sensoriamento remoto : estudo de caso para o estado do Rio Grande do Sul; Precipitation estimation by remote sensing techniques : estudy case for rio grande do sul state

Conti, Guilherme Nobel
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.77%
A quantificação da precipitação é dificultada pela extrema aleatoriedade do fenômeno na natureza. Os métodos convencionais para mensuração da precipitação atuam no sentido de espacializar a precipitação mensurada pontualmente em postos pluviométricos para toda a área de interesse e, desta forma, uma rede com elevado número de postos bem distribuídos em toda a área de interesse é necessária para um resultado satisfatório. No entanto, é notória a escassez de postos pluviométricos e a má distribuição espacial dos poucos existentes, não somente no Brasil, mas em vastas áreas do globo. Neste contexto, as estimativas da precipitação com técnicas de sensoriamento remoto e geoprocessamento pretendem potencializar a utilização dos postos pluviométricos existentes através de uma espacialização baseada em critérios físicos. Além disto, o sensoriamento remoto é a ferramenta mais capaz para gerar estimativas de precipitação nos oceanos e nas vastas áreas continentais desprovidas de qualquer tipo de informação pluviométrica. Neste trabalho investigou-se o emprego de técnicas de sensoriamento remoto e geoprocessamento para estimativas de precipitação no sul do Brasil. Três algoritmos computadorizados foram testados...

Mesoscale convective complexes in Rio Grande do Sul between october and december of 2003 and associated precipitation; Complexos convectivos de mesoescala no Rio Grande do Sul entre outubro e dezembro de 2003 e quantificação da precipitação associada

Viana, Denilson Ribeiro; Aquino, Francisco Eliseu; Burgobraga, Ricardo; Ferreira, Nelson Jesus
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
36.77%
Este estudo investiga a ocorrência de Complexos Convectivos de Mesoescala (CCM) e a precipitação associada aos eventos no Estado do Rio Grande do Sul (RS), entre outubro e dezembro de 2003. A identificação dos CCM foi feita através do aplicativo ForTraCC e, para quantificação dos totais de precipitação oriundos de CCM, foram utilizados dados diários de 31 estações meteorológicas. Durante o período de estudo, foram identificados 22 eventos de CCM sobre o RS. Deste total, sete ocorreram em outubro, sete em novembro e oito em dezembro. Os dados analisados apontam para um volume médio de precipitação de CCM no RS de 119 mm em outubro, 90 mm em novembro e 152 mm em dezembro. Do total de precipitação registrado para o período, o percentual oriundo de CCM ficou em 64% no mês de outubro, 65% em novembro e 61% em dezembro. O volume médio de precipitação de CCM acumulado no trimestre ficou em 361 mm, uma participação percentual de 63%, confirmando que os CCM contribuíram significativamente para a precipitação no Estado e foram responsáveis por quase dois terços da chuva observada no RS no período.; This study investigates the occurrences of Mesoscale Convective Complexes (MCC) and the associated precipitation in the southernmost Brazilian state...

A precipitation-based regionalization for Western Iran and regional drought variability

Raziei, T.; Bordi, I.; Pereira, L.S.
Fonte: European Geosciences Union Publicador: European Geosciences Union
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
Relevância na Pesquisa
36.8%
Abstract. The spatial distribution of the seasonal and annual precipitation was analyzed in western Iran using data from 140 stations covering the period 1965–2000. Applying the Precipitation Concentration Index (PCI), the intraannual precipitation variability was also studied. Furthermore, nine precipitation-derived parameters were used to regionalize climate in western Iran using principal component analysis and clustering techniques. Results suggest that five spatially homogenous sub-regions can be identified characterized by different precipitation regimes. The spatial pattern of seasonal precipitation seems to be highly controlled by the wide latitudinal extent of the region and by the pronounced orographic relieves, and the time of occurrence of the maximum precipitation varies from spring in the north to winter in the south. The time variability of dry and wet periods in the identified sub-regions was analyzed using the Precipitation Index (PI) and the existence of any long-term trend was tested. Results show that the northern and southern regions of western Iran are characterized by different climatic variability. Furthermore, a negative long-term linear trend in the north and a weak positive trend in the south of the study area have been detected though they are not statistically significant

Regional climate gradients in precipitation and temperature in response to climate teleconnections in the Greater Everglades ecosystem of South Florida

Moses, Christopher S.; Anderson, William T.; Saunders, Colin; Sklar, Fred
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.8%
Precipitation and temperature in Florida responds to climate teleconnections from both the Pacific and Atlantic regions. In this region south of Lake Okeechobee, encompassing NWS Climate Divisions 5, 6, and 7, modern movement of surface waters are managed by the South Florida Water Management District and the US Army Corps of Engineers for flood control, water supply, and Everglades restoration within the constraints of the climatic variability of precipitation and evaporation. Despite relatively narrow, low-relief, but multi-purposed land separating the Atlantic Ocean from the Gulf of Mexico, South Florida has patterns of precipitation and temperature that vary substantially on spatial scales of 101–102 km. Here we explore statistically significant linkages to precipitation and temperature that vary seasonally and over small spatial scales with El Niño-Southern Oscillation (ENSO), the Atlantic Multidecadal Oscillation (AMO), and the Pacific Decadal Oscillation (PDO). Over the period from 1952 to 2005, ENSO teleconnections exhibited the strongest influence on seasonal precipitation. The Multivariate ENSO Index was positively correlated with winter (dry season) precipitation and explained up to 34 % of dry season precipitation variability along the southwest Florida coast. The AMO was the most influential of these teleconnections during the summer (wet season)...

Numerical modeling as support to the study of precipitation over the Madeira Island (Portugal); Utilização de simulações numéricas como apoio no estudo de precipitação na Ilha da Madeira (Portugal)

Couto, Flavio; Ducrocq, Véronique; Salgado, Rui; costa, Maria João
Fonte: cbmet2014 Publicador: cbmet2014
Tipo: Aula
ENG
Relevância na Pesquisa
36.81%
The Madeira is a small mountainous island (~740 km2) located in the North Atlantic Ocean (32°75'N and 17°00'W), and after the disaster occurred on 20 February 2010, when extreme precipitation induced flash floods and landslides in some spots of the island, efforts have been directed toward the understanding of the precipitation affecting the island. The occurrence of extreme precipitation in three seasons in the last years have raised questions mainly about the atmospheric conditions that may lead to the development of intense precipitation with high impact at the surface. Our goals in this work are to identify and describe the large- and meso- scale features associated to four periods of significant accumulated precipitation during the autumn 2012. The precipitation recorded by the Madeira meteorological network is analyzed, as well as satellite images in order to describe the characteristics of the precipitation systems that reached the Madeira in each period. The synoptic scale conditions are described thank to the 6-hourly ARPEGE operational analyses. The four periods were associated with different large-scale precipitating systems. The mesoscale environment and precipitating systems have been then studied thank to very-high resolution numerical simulations using the MESO-NH non-hydrostatic model. The numerical experiments were carried out using as initial and boundary conditions the ARPEGE analyses. The model was configured in two two-way nested domains: the larger domain with a grid spacing of 2.5 km and 600x500 points...

Isotopic characterization of mountain precipitation along the eastern flank of the Andes between 32.5 ? 35°S

Hoke, Gregory D.; Aranibar, Julieta Nelida; Viale, Maximiliano; Araneo, Diego Christian; Llano, Carina Lourdes
Fonte: Amer Geophysical Union Publicador: Amer Geophysical Union
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
36.8%
Constraining the influence of different moisture sources across the flanks of mountain ranges isimportant for understanding tectonic, geomorphic, and paleoclimate problems at geologic timescales, aswell as evaluating climate change and water resources on human time scales. The stable isotope compositionsof stream waters and precipitation are an ideal tool for this task. This study reports the results of a2 year monthly precipitation sampling campaign on the eastern flank of the Andes in the Mendoza Province of Argentina, which began in September 2008. A total of 104 precipitation samples spanning some 2500mof relief from nine sites were analyzed for dD and d18O. In addition, 81 samples from Andean riverscollected on both sides of the range in 2002 and 2007 were analyzed. We employ a Rayleigh isotope fractionation modeling approach to explore spatial and temporal variations in precipitation and river water compositions. The results indicate that precipitation on the eastern slopes of the Andes at ~33S, at elevations above 2 km, is largely derived from a westerly, Pacific-source component and a mixture of easterly and westerly sources below 2 km. Further south at ~35S, river water compositions exhibit a strong winter influence. At 33S...

Características de las precipitaciones orográficas de invierno sobre los Andes Subtropicales Centrales; Characteristics of the winter orographic precipitation over the Subtropical Central Andes

Viale, Maximiliano
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2010 SPA
Relevância na Pesquisa
36.89%
Las precipitaciones sobre las montañas son en gran parte originadas o incrementadas cuando el flujo horizontal de aire húmedo es forzado a ascender por la topografía. Esta situación se produce mayormente en el invierno sobre los Andes Centrales (30º -37ºS), cuando el flujo del oeste intenso de un ciclón extratropical llega hasta latitudes subtropicales. Debido a la escasa información disponible en la cordillera, las variaciones de la precipitación son documentadas en una escala transversal a la misma que no tiene en cuenta variaciones entre valles y picos. A partir de 7 años (1970-1976) de datos de precipitación de invierno (Abr-Sep) disponible, la máxima cantidad de precipitación se observó sobre zonas pendiente arriba de la cordillera antes de alcanzar la cresta, siendo aproximadamente el doble de la cantidad de precipitación observada en zonas bajas a barlovento. Inmediatamente a sotavento de los picos más altos, la cantidad de precita- ción cae drásticamente generando un notorio gradiente transversal a la cordillera, con precipitaciones largamente disminuidas en zonas bajas a sotavento. Esta disminución fue mayor en zonas bajas del norte de Mendoza (31.5º-34.5ºS) que del sur (35º -36.5ºS), probablemente debido a la mayor actividad baroclinica y un decaimiento de la altura de la cordillera hacia el sur...

Responses of terrestrial ecosystems to temperature and precipitation change: a meta-analysis of experimental manipulation

Wu, Zhuoting; Dijkstra, Paul; Koch, George; Peñuelas, Josep; Hungate, Bruce
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2011 ENG
Relevância na Pesquisa
36.85%
Global mean temperature is predicted to increase by 2–7 °C and precipitation to change across the globe by the end of this century. To quantify climate effects on ecosystem processes, a number of climate change experiments have been established around the world in various ecosystems. Despite these efforts, general responses of terrestrial ecosystems to changes in temperature and precipitation, and especially to their combined effects, remain unclear. We used meta-analysis to synthesize ecosystem-level responses to warming, altered precipitation, and their combination. We focused on plant growth and ecosystem carbon (C) balance, including biomass, net primary production (NPP), respiration, net ecosystem exchange (NEE), and ecosystem photosynthesis, synthesizing results from 85 studies. We found that experimental warming and increased precipitation generally stimulated plant growth and ecosystem C fluxes, whereas decreased precipitation had the opposite effects. For example, warming significantly stimulated total NPP, increased ecosystem photosynthesis, and ecosystem respiration. Experimentally reduced precipitation suppressed aboveground NPP (ANPP) and NEE, whereas supplemental precipitation enhanced ANPP and NEE. Plant productivity and ecosystem C fluxes generally showed higher sensitivities to increased precipitation than to decreased precipitation. Interactive effects of warming and altered precipitation tended to be smaller than expected from additive...

CMIP5 model simulations of Ethiopian Kiremt-season precipitation: current climate and future changes

Li, Laifang; Li, W; Ballard, Tristan; Ge Sun; Jeuland, Marc
Fonte: Springer Verlag (Germany) Publicador: Springer Verlag (Germany)
Tipo: Artigo de Revista Científica
Publicado em 07/07/2015
Relevância na Pesquisa
36.87%
Kiremt-season (June–September) precipitation provides a significant water supply for Ethiopia, particularly in the central and northern regions. The response of Kiremt-season precipitation to climate change is thus of great concern to water resource managers. However, the complex processes that control Kiremt-season precipitation challenge the capability of general circulation models (GCMs) to accurately simulate precipitation amount and variability. This in turn raises questions about their utility for predicting future changes. This study assesses the impact of climate change on Kiremt-season precipitation using state-of-the-art GCMs participating in the Coupled Model Intercomparison Project Phase 5. Compared to models with a coarse resolution, high-resolution models (horizontal resolution <2°) can more accurately simulate precipitation, most likely due to their ability to capture precipitation induced by topography. Under the Representative Concentration Pathway (RCP) 4.5 scenario, these high-resolution models project an increase in precipitation over central Highlands and northern Great Rift Valley in Ethiopia, but a decrease in precipitation over the southern part of the country. Such a dipole pattern is attributable to the intensification of the North Atlantic subtropical high (NASH) in a warmer climate...

The Integrated Precipitation and Hydrology Experiment - Hydrologic Applications for the Southeast US (IPHEx-H4SE) Part III: High-Resolution Ensemble Rainfall Products

Nogueira, Miguel; Barros, Ana
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Artigo de Revista Científica
Publicado em 14/01/2014
Relevância na Pesquisa
36.8%
The first stage of the Integrated Precipitation and Hydrology Experiment (IPHEX) includes the 37 development of quality-controlled data sets of different hydrometeorological and landscape attributes at high spatial and temporal resolutions (respectively 1km×1km and 1 hour). These data sets will facilitate the intercomparison of hydrological models and provide support to the ground validation campaign of GPM over the Southern Appalachian region. In the present report we focus on the spatial downscaling of Stage IV precipitation data (Baldwin and Mitchell, 1996; Lin and Mitchell, 2005; see online at http://www.emc.ncep.noaa.gov/mmb/ylin/pcpanl/stage4) from 4km to 1km resolution for the period 2007-2011. First, we describe the 44 methodologies utilized to develop the various QPE products and in particular the use of modified fractal downscaling methodologies, which conserve the spatial structure of the coarse resolution while enhancing sub-grid scale variability. Three different (hourly, 1km2) precipitation datasets were produced: 1) Stage IV bilinear interpolated fields; 2) Stage IV fractal downscaled fields using (with 50 ensemble realizations for each hour); and 3) Stage IV fractal downscaled fields using a transient (with 50 ensemble realizations for each hour). The realizations 50 provided for each hour in the fractal downscaled cases should be particularly useful to ensemble hydrologic applications and analysis of uncertainty propagation. The performance of the downscaled QPE (Quantitative Precipitation Estimation) products is subsequently evaluated for selected headwater basins in the Southern Appalachians for individual events and for 5 year continuous simulations in three watersheds...

Daily precipitation distributions over the intra-Americas sea and their interannual variability

Curtis,S.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 EN
Relevância na Pesquisa
36.84%
The seasonal (March to October) and interannual variability of the cumulative distribution function (CDF) of precipitation is examined for Meso-America, the eastern Pacific and western Atlantic, commonly referred to as the intra-Americas sea (IAS). Large-area precipitation CDFs were constructed over land and temperature pools greater than 28.5° C and between 26.5° and 28.5° C. The cooler waters tend to have their precipitation distributions shifted to lower values as compared to land and the western hemisphere warm pool (WHWP). The land and the WHWP have similar precipitation distributions from March to May. From June to October the land histogram of precipitation is narrower (less light and heavy rainfall) relative to the WHWP histogram. The highest probability of finding heavy to extreme precipitation over the WHWP is in June. From 1997 to 2008, in the summer months, the El Niño/Southern Oscillation (ENSO) is related to the CDFs of precipitation over land, where during El Niño there is a shift toward lower daily rain totals. There is not a strong relationship between ENSO and the CDFs of precipitation over the ocean pools. Finally, a large WHWP in May-June-July is related to the CDF of precipitation over the WHWP in October...

The El Niño/Southern Oscillation and Precipitation Variability in Baja California, Mexico

MINNICH,RICHARD A.; FRANCO VIZCAÌNO,ERNESTO; DEZZANI,RAYMOND J.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2000 EN
Relevância na Pesquisa
36.86%
This study evaluates precipitation variability in Baja California in relation to the El Niño/Southern Oscillation (ENSO) using the Southern Oscillation Index (SOI). To evaluate precipitation climatology, data for 102 weather stations were analyzed. Data were directly averaged for stations with records longer than 30 years, but normalized for stations with shorter records. To test for uniformity of precipitation departures, the SOI was compared with average precipitation departures for long-term stations (established before 1960), in eight subregions of Baja California. The results revealed that, unlike California, the interannual variability of both annual and monthly precipitation is strongly linked to SOI. During El Niño events, above-normal precipitation occurs largely in February and March; but precipitation amounts are subnormal during La Niña events, and mostly limited to December and January. Gradients of precipitation departure tend to be uniform across Baja California during individual years. The variability of precipitation is attributed to the interannual dislocation by ENSO of the polar-front jet stream along the Pacific coast, as described in other studies. In El Niño events, the circulation acquires a positive-phase Pacific-North America (PNA) pattern...

Winter frequency of western disturbances and precipitation indices over Himachal Pradesh, India: 1977-2007

Kumar,Naresh; Yadav,B. P.; Gahlot,Shilpa; Singh,Manmohan
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2015 EN
Relevância na Pesquisa
36.83%
The Himalayas have an important role in Indian weather and climate, since they control the western disturbances (WDs) during winter and the southwest monsoon during summer. During the winter months (December to March), westerly winds associated with WDs cause precipitation, sometimes along with heavy snowfall, extensive avalanches, etc., over Himachal Pradesh. Therefore, this study examined the temporal variability in the winter months frequency of WDs and various precipitation indices like wet days, rainy days, rather heavy and heavy precipitation days, and precipitation intensity during 1977 to 2007 over Himachal Pradesh. The study also examined synoptic features associated with intense WDs that caused heavy precipitation over the region during the same period. Analysis of data reveals a statistically significant (confidence level > 95%) decreasing trend in the frequency of WDs over this region. Since winter precipitation in Himachal Pradesh mainly occurs due to WDs, total winter precipitation and frequency of rather heavy and heavy precipitation days have decreased over the region. The analysis also shows a decrease of about 25% in heavy precipitation days and of 13% in total winter precipitation from their respective mean (from 1977 to 2007) over Himachal Pradesh.

Urban effects on precipitation in Ankara

ÇIÇEK,I.; TURKOGLU,N.
Fonte: Centro de Ciencias de la Atmósfera, UNAM Publicador: Centro de Ciencias de la Atmósfera, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2005 EN
Relevância na Pesquisa
36.84%
In this study, trends of the precipitation day classes in the warm period (May-September) were investigated for Ankara. Data collected by Ankara Meteorology Station (AMS) which has urban characters, and Esenboga Meteorology Station (EMS) which has rural characters, were statistically analyzed to understand the trends of the precipitation day classes. At both, the urban and rural stations, an increase was observed in the number of precipitation days and light precipitation days within years. However, the number of heavy precipitation days increased at the station with urban character (AMS), while it decreased at the station with rural character (EMS). A 50% increase was observed in the number of heavy precipitation days at the urban station (AMS) in comparison with that of the rural station (EMS). The increasing trend in the precipitation and light precipitation days at both stations may be related to the changes in climate. However, the increase in the number of heavy precipitation days only at the station with urban character (AMS) may be due to urbanization.

Precipitation of rhodium from a copper sulphate leach solution in the selenium/tellurium removal section of a base metal refinery

Lottering,C; Eksteen,J.J; Steenekampt,N
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 EN
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36.84%
Copper sulphate solutions are produced during the pressure leaching of first-stage leach residue in a typical base metal refinery process. Apart from impurities such as selenium and tellurium, this leach solution also contains other precious metals (Rh, Ru, and Ir) due to dissolution in the pressure leaching stage. Selenium and tellurium are removed from the leach solution by precipitation with sulphurous acid, since these elements negatively affect electrowinning. This study investigates the feasibility of modifying the Se/Te precipitation process step to achieve significant rhodium precipitation in addition to selenium and tellurium precipitation, in order to reduce the rhodium inventory of the process. Thiourea, SO2, formaldehyde, formic acid, and sodium thiosulphate were evaluated to determine which of these reagents would achieve the highest Rh precipitation. Based on these screening tests, SO2 and thiourea were selected to be used as precipitation reagents in optimization tests. During these optimization tests, the operating temperature (80 to 150°C) and the amount of reagent added (80 to 140 per cent excess) were varied to evaluate the effects that these operating conditions have on the precipitation behaviour of Rh as well as Se...

Oxidative precipitation of Mn(II) from cobalt leach solutions using dilute SO2/air gas mixture

Mulaudzi,N.; Mahlangu,T.
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 EN
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36.8%
The use of SO2/air gas mixtures as an oxidant to precipitate Mn from Co(II) leach liquors was investigated. The effects of SO2/air ratio, pH and temperature on Mn precipitation were evaluated. It was found that the use of SO2/air gas mixtures resulted in significantly higher Mn precipitation kinetics compared to using air or pure O2alone. The SO2/air ratio was varied from 0% to 6% SO2 (v/v) in air and similar Mn removals were achieved at 0.75% to 3% SO2at pH 3. The solution pH was varied from pH 2 to pH 4; Mn precipitation did not increase considerably from pH 2 to pH 3, but increased significantly at pH values higher than pH 3. Cobalt co-precipitation also increased as pH increased, with 1% Co co-precipitation at pH 3. An increase in temperature from 30°C to 60°C also increased Mn precipitation and 100% Mn precipitated at 50°C. Cobalt co-precipitation also increased significantly with an increase in temperature. An activation energy of 25 kJ/mol was calculated from the Arrhenius plot, which is an indication that the precipitation reactions were both chemically and diffusion controlled. XRD analysis showed that Mn precipitated in the form of Mn2O3instead of MnO2 that was predicted from thermodynamic data. SEM and XRD analysis also revealed that the precipitate consisted mainly of gypsum or bassanite (99%)...