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Ratios of UV, PAR and NIR components to global solar radiation measured at Botucatu site in Brazil

ESCOBEDO, Joao F.; GOMES, Eduardo N.; OLIVEIRA, Amauri R.; SOARES, Jacyra
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.27%
The relationships between the four radiant fluxes are analyzed based on a 4 year data archive of hourly and daily global ultraviolet (I(UV)), photosynthetically active-PAR (I(PAR)), near infrared (I(NIR)) and broadband global solar radiation (I(G)) collected at Botucatu, Brazil. These data are used to establish both the fractions of spectral components to global solar radiation and the proposed linear regression models. Verification results indicated that the proposed regression models predict accurately the spectral radiant fluxes at least for the Brazilian environment. Finally, results obtained in this analysis agreed well with most published results in the literature. (c) 2010 Elsevier Ltd. All rights reserved.; FAPESP; CAPES; CNPq

Modeling hourly and daily fractions of UV, PAR and NIR to global solar radiation under various sky conditions at Botucatu, Brazil

ESCOBEDO, Joao F.; GOMES, Eduardo N.; OLIVEIRA, Amauri P.; SOARES, Jacyra
Fonte: ELSEVIER SCI LTD Publicador: ELSEVIER SCI LTD
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.28%
In this analysis, using available hourly and daily radiometric data performed at Botucatu, Brazil, several empirical models relating ultraviolet (UV), photosynthetically active (PAR) and near infrared (NIR) solar global components with solar global radiation (G) are established. These models are developed and discussed through clearness index K(T) (ratio of the global-to-extraterrestrial solar radiation). Results obtained reveal that the proposed empirical models predict hourly and daily values accurately. Finally. the overall analysis carried Out demonstrates that the sky conditions are more important in developing correlation models between the UV component and the global solar radiation. The linear regression models derived to estimate PAR and NIR components may be obtained without sky condition considerations within a maximum variation of 8%. In the case of UV, not taking into consideration the sky condition may cause a discrepancy of up to 18% for hourly values and 15% for daily values. (C) 2008 Elsevier Ltd. All rights reserved.

Comparação da atenuação da radiação solar e dos fatores que determinam o clima de radiação solar subaquática em lagos e reservatórios do Brasil; Comparison of solar radiation attenuation and factors that determine underwater solar radiation climate in lakes and reservoirs of Brazil

Rodrigues, Sonia Luiz
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 26/03/2003 PT
Relevância na Pesquisa
66.38%
O estudo da penetração da radiação solar no meio aquático foi desenvolvido em quatro partes. Na primeira delas, voltada para a atenuação da radiação solar na coluna d’água, foram discutidos fatores de interferência e suas inter-relações. Neste sentido, foi feita uma comparação da penetração da radiação solar em ecossistemas continentais naturais e artificiais, analisando as diferenças e similaridades. O estudo comparativo da atenuação da radiação solar subaquática em toda extensão de reservatórios constituiu a segunda parte deste trabalho. A comparação foi feita entre reservatórios que apresentam proximidades de localização, mas com diferenças marcantes nos usos e ocupações nas regiões em que os mesmos estão inseridos. Na terceira parte foram apresentados dois recursos de grande utilização na obtenção das respostas imediatas do ambiente aquático, do ponto de vista óptico, diante dos impactos sofridos. O primeiro recurso foi a determinação do espectrograma da radiação solar, indicando a atenuação da radiação solar subaquática na faixa fotossinteticamente ativa (400 nm - 700 nm). O outro recurso foi a obtenção do espectro de absorção da água superficial, que permitiu o estabelecimento do “Índice de Absorção Espectral da Água”...

Ratios of UV, PAR and NIR components to global solar radiation measured at Botucatu site in Brazil

Escobedo, João Francisco; Gomes, Eduardo N.; Oliveira, Amauri R.; Soares, Jacyra
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Conferência ou Objeto de Conferência Formato: 169-178
ENG
Relevância na Pesquisa
66.26%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); The relationships between the four radiant fluxes are analyzed based on a 4 year data archive of hourly and daily global ultraviolet (I(UV)), photosynthetically active-PAR (I(PAR)), near infrared (I(NIR)) and broadband global solar radiation (I(G)) collected at Botucatu, Brazil. These data are used to establish both the fractions of spectral components to global solar radiation and the proposed linear regression models. Verification results indicated that the proposed regression models predict accurately the spectral radiant fluxes at least for the Brazilian environment. Finally, results obtained in this analysis agreed well with most published results in the literature. (c) 2010 Elsevier Ltd. All rights reserved.

Modeling hourly diffuse solar-radiation in the city of São Paulo using a neural-network technique

Soares, J.; Oliveira, A. P.; Boznar, M. Z.; Mlakar, P.; Escobedo, J. F.; Machado, A. J.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 201-214
ENG
Relevância na Pesquisa
66.29%
dIn this work, a perceptron neural-network technique is applied to estimate hourly values of the diffuse solar-radiation at the surface in São Paulo City, Brazil, using as input the global solar-radiation and other meteorological parameters measured from 1998 to 2001. The neural-network verification was performed using the hourly measurements of diffuse solar-radiation obtained during the year 2002. The neural network was developed based on both feature determination and pattern selection techniques. It was found that the inclusion of the atmospheric long-wave radiation as input improves the neural-network performance. on the other hand traditional meteorological parameters, like air temperature and atmospheric pressure, are not as important as long-wave radiation which acts as a surrogate for cloud-cover information on the regional scale. An objective evaluation has shown that the diffuse solar-radiation is better reproduced by neural network synthetic series than by a correlation model. (C) 2004 Elsevier Ltd. All rights reserved.

Modeling hourly and daily fractions of UV, PAR and NIR to global solar radiation under various sky conditions at Botucatu, Brazil

Escobedo, João Francisco; Gomes, Eduardo N.; Oliveira, Amauri P.; Soares, Jacyra
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 299-309
ENG
Relevância na Pesquisa
66.26%
In this analysis, using available hourly and daily radiometric data performed at Botucatu, Brazil, several empirical models relating ultraviolet (UV), photosynthetically active (PAR) and near infrared (NIR) solar global components with solar global radiation (G) are established. These models are developed and discussed through clearness index K(T) (ratio of the global-to-extraterrestrial solar radiation). Results obtained reveal that the proposed empirical models predict hourly and daily values accurately. Finally. the overall analysis carried Out demonstrates that the sky conditions are more important in developing correlation models between the UV component and the global solar radiation. The linear regression models derived to estimate PAR and NIR components may be obtained without sky condition considerations within a maximum variation of 8%. In the case of UV, not taking into consideration the sky condition may cause a discrepancy of up to 18% for hourly values and 15% for daily values. (C) 2008 Elsevier Ltd. All rights reserved.

Diurnal evolution of solar radiation at the surface in the city of São Paulo: Seasonal variation and modeling

Oliveira, A. P. de; Machado, A. J.; Escobedo, J. F.; Soares, J.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 213-250
ENG
Relevância na Pesquisa
66.3%
Seasonal variations in the diurnal evolution of the global, diffuse and direct solar radiation at the surface, the clearness index, diffuse fraction and direct fraction are described in detail for the City of Sao Paulo, Brazil. The description is based on measurements of global and diffuse solar radiation carried out over 5.25 years. The diffuse component was measured with a shadow-band device. The annual evolution of the amplitude of the diurnal cycle of all radiometric parameters indicates a seasonal pattern with two distinct periods: autumn-winter and spring-summer. About 10% of the observed period was characterized by clear sky days. This seasonal variation is determined by a larger incidence of clear sky days in the autumn-winter period. Reductions of up to 10% in hourly and daily values of global radiation were observed in conjunction with an increase in particulate matter concentration on clear sky days. The pollution effect may be responsible for the discrepancy, of 16%, found between local and more regional estimates of global solar radiation in Sao Paulo. The diurnal evolution of hourly values of monthly-averaged global and diffuse solar radiation were successfully estimated by the empirical expressions derived here. Daily values of monthly-averaged global solar radiation were satisfactorily estimated using the Angstrom expression.

Balance of longwave radiation employing the rate of solar radiation for Santa Maria, Rio Grande do Sul, Brazil1

Righi,Evandro Zanini; Heldwein,Arno Bernardo; Maldaner,Ivan Carlos; Lucas,Dionéia Daiane Pittol; Stüker,Paulo Ervin
Fonte: Universidade Federal do Ceará Publicador: Universidade Federal do Ceará
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2015 EN
Relevância na Pesquisa
66.24%
New coefficients were determined for the weighting term for cloudiness in the Brunt-Penman equation using the rate of solar radiation (RK) in place of the rate of sunshine duration (n/N). The coefficients in the Brutsaert method proposed for daytime in southern Brazil were also tested and adjusted, and the method was selected which gave the more accurate daily results in relation to the original Brunt-Penman equation, for Santa Maria in the state of Rio Grande do Sul, Brazil (RS). Meteorological data covering 2,472 days obtained from the automatic and conventional weather stations in Santa Maria were used. The coefficients were adjusted by linear and nonlinear regression methods depending on the model, using 2/3 of the data. The adjusted equations were tested with the remaining 1/3 of the data. The Brunt-Penman equation modified by the term for cloudiness weighted both for solar radiation incident on the surface with no cloudiness (RK,R) and for solar radiation incident at the top of the atmosphere (RK,K), were those that resulted in the best statistical indices relative to the original Brunt-Penman equation. In those equations the boundary conditions...

Sensitivity of APSIM/ORYZA model due to estimation errors in solar radiation.

HEINEMANN, A. B.; VAN OORT, P. A. J.; FERNANDES, D. S.; MAIA, A. de H. N.
Fonte: Bragantia, Campinas, v. 71, n. 4, p. 572-582, 2012. Publicador: Bragantia, Campinas, v. 71, n. 4, p. 572-582, 2012.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
66.3%
Crop models are ideally suited to quantify existing climatic risks. However, they require historic climate data as input. While daily temperature and rainfall data are often available, the lack of observed solar radiation (Rs) data severely limits site- specific crop modelling. The objective of this study was to estimate Rs based on air temperature solar radiation models and to quantify the propagation of errors in simulated radiation on several APSIM/ORYZA crop model seasonal outputs, yield, biomass, leaf area (LAI) and total accumulated solar radiation (SRA) during the crop cycle. The accuracy of the 5 models for estimated daily solar radiation was similar, and it was not substantially different among sites. For water limited environments (no irrigation), crop model outputs yield, biomass and LAI was not sensitive for the uncertainties in radiation models studied here.; 2012

Avaliação da radiação solar em ecossistema de manguezal tropical em Alagoas, Brasil; Solar radiation valuation in tropical mangrove ecossystem in Alagoas, Brazil

Querino, Carlos Alexandre Santos
Fonte: Universidade Federal de Alagoas; BR; Processos de superfície terrestre; Programa de Pós-Graduação em Meteorologia; UFAL Publicador: Universidade Federal de Alagoas; BR; Processos de superfície terrestre; Programa de Pós-Graduação em Meteorologia; UFAL
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
66.34%
The mangroves forests have a high social, economical and environmental importance because they are consists of a rich faun and flora. Brazil has one of the biggest mangrove areas in the world which expands from its North to the South coast. Actually, one of the main environmental issues is the deforesting, such as, the mangrove conversion into degraded area, exchanging the net radiation. The mangrove transformation in degraded area influences directly the regional microclimate for the soil is exposed to direct solar radiation altering the net radiation. Solar radiation is all electromagnetic radiation coming from the Sun, reaching the earth. Therefore, the knowledge above the Solar Global Radiation behavior, and its components (Direct (RD) and Diffuse (Rd)), within and outside forests, is essential to understand of the various processes in this system. The study has been carried out with data of originally from two experimental sites, with different vegetal cover (natural and degraded mangrove), located in Marechal Deodoro city (Alagoas), inside an environmental protection area (APA) called Santa Rita, which coordinates are between 9º37 30 - 9º47 30 S and 35º45 00 - 35º55 00 W, ranging from October 2004 to September 2005...

Avaliação de melanócitos humanos expostos ao inseticida carbaril e à radiação solar em cultura; Evaluation of cultured human melanocytes exposed to carbaryl insecticide and solar radiation

Ferrucio, Bianca
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 05/03/2015 PT
Relevância na Pesquisa
66.38%
O carbaril (metilcarbamato de naftila), um inseticida de amplo espectro, foi recentemente associado ao desenvolvimento de melanoma cutâneo em estudo epidemiológico de coorte com trabalhadores agrícolas norte-americanos, expostos também à radiação solar, o principal fator etiológico para o desenvolvimento de tumores cutâneos. Apesar de abrangente e bem planejado, aquele estudo epidemiológico não é suficiente para caracterizar a contribuição direta do inseticida e da radiação solar na melanomagênese. Diversos estudos têm explorado o efeito sinérgico de determinadas substâncias químicas à radiação UV, potencializando seus efeitos deletérios sobre a pele, e possivelmente contribuindo para o desenvolvimento de tumores. A hipótese deste trabalho é de que a exposição ao carbaril associada à radiação solar possa estimular a transformação de melanócitos. Esse estudo visou caracterizar melanócitos humanos após exposição individual ou combinada ao carbaril (100uM) e à radiação solar (375 mJ/ cm2). Em ensaio de microarray, o carbaril, mas não a radiação solar, induziu uma importante resposta a estresse oxidativo, evidenciada pelo aumento da expressão de genes antioxidantes, como o Hemeoxigenase-1 (HMOX1)...

Evaluation of measurement errors of temperature and relative humidity from HOBO data logger under different conditions of exposure to solar radiation

Cunha, Antonio Ribeiro da
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica Formato: 1-11
ENG
Relevância na Pesquisa
66.26%
This study aimed to assess measurements of temperature and relative humidity obtained with HOBO a data logger, under various conditions of exposure to solar radiation, comparing them with those obtained through the use of a temperature/relative humidity probe and a copper-constantan thermocouple psychrometer, which are considered the standards for obtaining such measurements. Data were collected over a 6-day period (from 25 March to 1 April, 2010), during which the equipment was monitored continuously and simultaneously. We employed the following combinations of equipment and conditions: a HOBO data logger in full sunlight; a HOBO data logger shielded within a white plastic cup with windows for air circulation; a HOBO data logger shielded within a gill-type shelter (multi-plate prototype plastic); a copper-constantan thermocouple psychrometer exposed to natural ventilation and protected from sunlight; and a temperature/relative humidity probe under a commercial, multi-plate radiation shield. Comparisons between the measurements obtained with the various devices were made on the basis of statistical indicators: linear regression, with coefficient of determination; index of agreement; maximum absolute error; and mean absolute error. The prototype multi-plate shelter (gill-type) used in order to protect the HOBO data logger was found to provide the best protection against the effects of solar radiation on measurements of temperature and relative humidity. The precision and accuracy of a device that measures temperature and relative humidity depend on an efficient shelter that minimizes the interference caused by solar radiation...

GIS-based modelling of topographyinduced solar radiation variability in complex terrain for data sparse region

Liu, M.; Bardossy, A.; Li, J.; Jiang, Y.
Fonte: Taylor & Francis Ltd Publicador: Taylor & Francis Ltd
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
66.38%
Solar radiation not only sustains the lives on the Earth, but also creates spatial and temporal variations of hydrological ingredients, such as vegetation, soil moisture, and snow. Precise quantification of spatial solar radiation incident on the Earth's surface which accounts for the topographic modulation, especially in complex terrain, underpins the study of many catchment hydro-meteorological and hydro-ecological processes. Topography is a key parameter that affects the spatial solar radiation pattern across different scales. This article addresses the issue of modelling spatial variability of actual solar radiation caused by topography from the hydrological perspective. Models with different algorithms and different complexities, from the simple empirical equations to process-based physical approach, have been developed to parameterize and calculate the potential radiation (under clear-sky condition) and the actual radiation (under overcast cloudy condition). Based on a review of the general steps of solar radiation modelling and the corresponding models for each step, two models with easily or globally available data for spatial solar radiation modelling in complex terrain, namely, the physically parameterized, remote-sensing-oriented Heliosat-2 model and the sunshine duration-based Angström–Prescott regression model are selected and implemented in a GIS framework. The capability of both models for simulation of cloudy-sky radiation on horizontal surfaces has been verified against observed station data showing an R ² greater than 0.9. The validity of the models for modelling inclined surface is tested by comparing against each other...

Measurement and simulation of solar radiation availability in relation to the growth of coffee plants in an agroforestry system with rubber trees

Righi,Ciro Abbud; Bernardes,Marcos Silveira; Lunz,Aureny Maria Pereira; Pereira,Carlos Rodrigues; Dourado Neto,Durval; Favarin,José Laercio
Fonte: Sociedade de Investigações Florestais Publicador: Sociedade de Investigações Florestais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2007 EN
Relevância na Pesquisa
66.33%
Solar radiation is an important factor for plant growth, being its availability to understory crops strongly modified by trees in an Agroforestry System (AFS). Coffee trees (Coffea arabica - cv. Obatã IAC 1669-20) were planted at a 3.4 x 0.9 m spacing inside and aside rows of monocrops of 12 year-old rubber trees (Hevea spp.), in Piracicaba-SP, Brazil (22º42'30" S, 47º38'00" W - altitude: 546m). One-year-old coffee plants exposed to 25; 30; 35; 40; 45; 80; 90; 95 and 100% of the total solar radiation were evaluated according to its biophysical parameters of solar radiation interception and capture. The Goudriaan (1977) adapted by Bernardes et al. (1998) model for radiation attenuation fit well to the measured data. Coffee plants tolerate a decrease in solar radiation availability to 50% without undergoing a reduction on growth and LAI, which was approximately 2m².m-2 under this condition. Further reductions on the availability of solar radiation caused a reduction in LAI (1.5m².m-2), thus poor land cover and solar radiation interception, resulting in growth reduction.

Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Melo,Camila A.; De Toffoli,Ana L.; Moreira,Altair B.; Bisinoti,Márcia C.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2012 EN
Relevância na Pesquisa
66.26%
This study had as main objective to assess the effect of solar radiation on the capacity of the aquatic humic substances (AHS) to complex Al3+, Cr3+, CrO4(2-) and Ni2+. Microcosms were prepared with AHS from Preto River containing 5.0 mg L-1 of dissolved organic carbon and different concentrations of metal species, being exposed to solar radiation, in situ. Conditional stability constants obtained for the AHS-Cr3+, AHS-Ni2+ and AHS-CrO4(2-) complexes were 2.0 × 10-2, 1.1 × 10-5 and 2.6 × 10-2, respectively. The results showed that solar radiation is responsible for decreasing capacity complexation in 15-26% for AHS-Al3+, 15-72% for AHS-Cr3+, 12-18% for AHS-CrO4(2-) and 13-42% for AHS-Ni2+. We can conclude that solar radiation alters metals' availability previously complexed to AHS, making them available in the aquatic body.

Decomposition of Zn-ferrite for O 2 Generation by Concentrated Solar Radiation

Kaneko, H; Kodama, T; Gokon, N; Tamaura, Y; Lovegrove, Keith; Luzzi, Andreas
Fonte: Australian and New Zealand Solar Energy Society (ANZSES) Publicador: Australian and New Zealand Solar Energy Society (ANZSES)
Tipo: Conference paper
Relevância na Pesquisa
76.23%
The O2 generation step in two-step water splitting with Zn-ferrite/Zn, Fe3O4 system was studied with a stainless steel reactor having a window of quartz glass plate (Sandwich Reactor) using the 15 kW solar dish concentrator in Australian National University. The reactant flat layer with a small thickness in the Sandwich Reactor was assumed to simulate the flow section of the particle cloud reactor. The temperature of the sample attained 1750 K in a few minutes by concentrated solar radiation, and 40% molar of the Zn-ferrite was decomposed into Fe3O4 to produce Zn0.4Fe 2.6O4, which is the solid solution between ZnFe2O4 and Fe3O4. The laboratory experiment with the Xe beam irradiation showed that the Zn-ferrite decomposition reaction proceeds according to 3/2ZnFe 2O4=3/2Zn + Fe3O4 + O 2. In the solar furnace experiment, the metal Zn vapor produced according to this equation seems to be deposited on the surface of the inner wall of the reactor, or it seems to recombine with the released O 2, converting to ZnO under the condition without quenching system in the present experimental setup.

PERFORMANCE OF THE SIMULATION MODEL PGECLIMA_R DAILY SERIES OF SYNTHETIC GLOBAL SOLAR RADIATION TO DIFFERENT LOCATIONS IN THE STATE OF PARANÁ; DESEMPENHO DO MODELO PGECLIMA_R NA SIMULAÇÃO DE SÉRIES DIÁRIAS SINTÉTICAS DE RADIAÇÃO SOLAR GLOBAL PARA DIFERENTES LOCALIDADES DO ESTADO DO PARANÁ

FRUTEIRA, Rafaela Steimbach; Dep. Biologia Geral - UEPG/Ponta Grossa - PR; LEITE, Maysa de Lima; Dep. Biologia Geral - UEPG/Ponta Grossa-PR; VIRGENS FILHO, Jorim Sousa; Dep. de Matemática e Estatística – UEPG/Ponta Grossa–PR
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 20/06/2012 POR
Relevância na Pesquisa
66.32%
Tendo em vista a grande relevância da radiação solar na análise climática de uma região, o presente estudo objetiva avaliar o desempenho do modelo PGECLIMA_R na geração de séries diárias sintéticas de radiação solar global para diferentes localidades do estado do Paraná. Foram utilizadas séries históricas diárias de radiação solar global das localidades Cascavel, Guarapuava, Guaraqueçaba, Londrina, Palmas, Paranavaí, Ponta Grossa, cedidas pelo Instituto Agronômico do Paraná–IAPAR, compreendendo um período de 30 anos (1980-2009), que serviram para parametrização do modelo, o qual simulou cinco séries de 30 anos para cada localidade. Para testar a eficiência do modelo, os dados gerados foram analisados pelos testes t e F ao nível de significância de 5%, para comparar as médias mensais das séries simuladas e observadas e, analisar a variabilidade interanual das médias mensais, respectivamente. Paralelamente, utilizaram-se índices para verificar a correlação e a concordância entre as médias mensais simuladas e observadas. Os resultados mostraram que o PGECLIMA_R apresentou um desempenho muito bom na simulação de dados sintéticos de radiação solar global...

Relationship between solar radiation and dimethylsulfide concentrations using in situ data for the pristine region of the southern hemisphere

Osorio,Jaime; Mendoza,Blanca; Zavala-Hidalgo,Jorge
Fonte: Instituto de Geofísica, UNAM Publicador: Instituto de Geofísica, UNAM
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2013 EN
Relevância na Pesquisa
66.26%
The biological processes have been proposed as climate variability contributors. Dimethylsulfide (DMS) is the main biogenic sulfur compound in the atmosphere; it is mainly produced by the marine biosphere and plays an important role in the atmospheric sulfur cycle. Currently it is accepted that terrestrial biota not only adapts to environmental conditions but also influences them through regulations of the chemical composition of the atmosphere. In the present study we used a wavelet method to investigate the relationship between DMS, Low cloud cover (LCC), Ultraviolet Radiation A (UVA), Total Solar Irradiance (TSI) and Sea Surface Temperature (SST) in the so called pristine zone of the Southern Hemisphere. We found that the series analyzed have different periodicities which can be associated with large scale climatic phenomena such as El Niño (ENSO) or the Quasi-Biennial Oscillation (QBO), and/or to solar activity. Our results show an intermittent but sustained DMS-SST correlation and a DMS-UVA anti correlation; but DMS-TSI and DMS-LCC show nonlinear relationships. The time-span of the series allow us to study only periodicities shorter than 11 years, then we limit our analysis to the possibility that solar radiation influences the Earth climate in periods shorter than the 11-year solar cycle. Our results also suggest a positive feedback interaction between DMS and solar radiation.

SASRAD: An hourly-timestep solar radiation database for South Africa

Ciolkosz,Daniel
Fonte: Journal of Energy in Southern Africa Publicador: Journal of Energy in Southern Africa
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
66.26%
A methodology is presented for the correction and filling of solar radiation data at sites within South Africa, with the aim of creating a continuous, hourly-timestep dataset for multiple locations. Data from twenty sites, collected by the Agricultural Research Council, are analysed with regard to the amount of data requiring offset or multiplier adjustment, as well as the amount of bad data. A range correction algorithm is implemented based on the 90th percentile (10% exceedance) hourly irradi-ance, as a function of site latitude and elevation. The resulting, corrected data set is given the title: South African Solar Radiation Database (SAS-RAD). Comparisons are made with two other solar radiation datasets, the South African Atlas of Agrohydrology and Climatology, and a limited set of older historical data from the South African Weather Service (SAWS). Results indicate that the SASRAD dataset matches well with other datasets, with major discrepancies apparently due to problems with the other data sets, rather than the SASRAD data. The Coefficient of Multiple Determination (R²) between the Atlas and SASRAD for monthly radiation is 0.927, and the mean error between three of the SASRAD sites and the corresponding SAWS data is 1.1 MJ m-2 d-1. The fraction of data requiring correction varied from 11% to 100%...

Estimation of global solar radiation in Venezuela.

Almorox,Javier; Benito,Marta; Hontoria,Chiquinquirá
Fonte: ASOCIACIÓN INTERCIENCIA Publicador: ASOCIACIÓN INTERCIENCIA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2008 EN
Relevância na Pesquisa
66.26%
A new relationship between sunshine duration and solar radiation was investigated through the analysis of data on monthly global solar radiation and hours of bright sunshine for eleven meteorological stations in Venezuela during the period 1964-1993. Linear regression was used to fit the Angström-Prescott equation. Estimated values were compared with measured values in terms of root mean square error, mean bias error, mean absolute bias error, mean percentage error, and mean absolute percentage error. It is recommended that the t-statistic be used in conjunction with a set of error statistical parameters to more reliably assess a model’s performance. All the models fitted the data adequately and can be used to estimate monthly mean solar global radiation from sunshine hours. The Angström-Prescott’s correlation obtained for the eleven cities can be used for estimating global solar radiation in Venezuela where only sunshine hours data were available.