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Radiation balance of coffee hedgerows; Balanço de radiação de renques de cafeeiros

ANGELOCCI, Luiz R.; MARIN, Fábio R.; PILAU, Felipe G.; RIGHI, Evandro Z.; FAVARIN, José L.
Fonte: Departamento de Engenharia Agrícola - UFCG Publicador: Departamento de Engenharia Agrícola - UFCG
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
56.29%
The radiation balance of hedgerows is an important variable in studies of mass and energy exchanges between parcial ground cover crops and the atmosphere. This paper describes a device with eight net radiometers encompassing the plants of a hedgerow. The radiometers were moved along a length of hedgerow, in a continuous and reversible movement. The canopy net radiation in this length (Rnc) was found by integration of the measurements over the notional cylinder formed. The device showed good performance and provided reliable measurements of Rnc of coffee hedgerows, showing itselfto be an useful technique of measurement in field conditions. Good correlations between Rnc and global solar radiation, turfgrass and coffee crop net radiation were found in 15-min, daytime and 24-hr periods, allowing the possibility of estimating Rnc from these simple measurements. Beer’s law was also used to have an independent estimation of Rnc. A good agreement was found between values of Rnc estimated by this law of attenuation and those integrated by the device in periods of 15 min, with overestimation of 10%, whereas for values integrated over daytime periods the agreement was not satisfactory.; A radiação, tanto de ondas curtas como de ondas longas...

Radiation balance at the surface in the city of So Paulo, Brazil: diurnal and seasonal variations

Ferreira, Mauricio Jonas; de Oliveira, Amauri Pereira; Soares, Jacyra; Codato, Georgia; Barbaro, Eduardo Wilde; Escobedo, Joao Francisco
Fonte: SPRINGER WIEN; WIEN Publicador: SPRINGER WIEN; WIEN
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
46.17%
The main goal of this work is to describe the diurnal and seasonal variations of the radiation balance components at the surface in the city of So Paulo based on observations carried out during 2004. Monthly average hourly values indicate that the amplitudes of the diurnal cycles of net radiation (Q*), downwelling and upwelling shortwave radiation (SW(DW), SW(UP)), and longwave radiations (LW(DW), LW(UP)) in February were, respectively, 37%, 14%, 19%, 11%, and 5% larger than they were in August. The monthly average daily values indicate a variation of 60% for Q*, with a minimum in June and a maximum in December; 45% for SW(DW), with a minimum in May and a maximum in September; 50% for SW(UP), with a minimum in June and a maximum in September; 13% for LW(DW), with a minimum in July and a maximum in January; and 9% for LW(UP), with a minimum in July and a maximum in February. It was verified that the atmospheric broadband transmissivity varied from 0.36 to 0.57; the effective albedo of the surface varied from 0.08 to 0.10; and the atmospheric effective emissivity varied from 0.79 to 0.92. The surface effective emissivity remained approximately constant and equal to 0.96. The albedo and surface effective emissivity for So Paulo agreed with those reported for urban areas in Europe and North America cities. This indicates that material and geometric effects on albedo and surface emissivity in So Paulo are similar to ones observed in typical middle latitudes cities. On the other hand...

Saldo de radiação da copa de laranjeira num pomar e de renques de cafeeiros: medidas e estimativas; Net radiation of orange tree canopy in an orchard and coffee hedgerows: measurements and estimates

Pilau, Felipe Gustavo
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 05/10/2005 PT
Relevância na Pesquisa
66.44%
A energia radiante absorvida pelas plantas é a principal determinante da taxa fotossintética, condicionando o crescimento e desenvolvimento vegetal, produção e qualidade dos produtos, sendo ainda uma variável fundamental na determinação da transpiração, possibilitando estabelecer relações entre essa variável e a evapotranspiração de referência, podendo-se determinar o coeficiente basal de culturas que orientarão nos processos de irrigação. Em vista da sua importância e do reduzido número de estudos de medida e estimativa do saldo de radiação da folhagem de arbóreas, objetivou-se realizar medidas do saldo de radiação de uma laranjeira (Rnl), cv. Pêra do Rio, com um sistema móvel de integração espaço-temporal para árvores “isoladas”, instalando-se oito saldo-radiômetros na armação circular vertical em torno da copa, que através do movimento de três rotações por minuto, criava uma esfera “sensora” de medida ao redor da planta, e de trechos de renques de um cafezal (Rnc) formado, variedade Mundo Novo Apuatã, e de cafezal em formação, variedade Obatã IAC 1669-20, utilizando-se um sistema móvel de integração espaço-temporal para cultivos em renques, no qual oito saldo-radiômetros, fixados em uma armação circular vertical em torno da folhagem...

Prognóstico das variáveis meteorológicas e da evapotranspiração de referência com o modelo de previsão do tempo GFS/NCEP; Prediction of meteorological variables and reference evapotranspiration with GFS/NCEP weather forecast model

Oliveira Filho, Celso Luís de
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 31/07/2007 PT
Relevância na Pesquisa
46.23%
Avaliou-se o desempenho de um modelo numérico de previsão do tempo (GFS - Global Forecast System – antigo AVN – AViatioN model - do Centro Nacional para Previsão Ambiental – NCEP) no prognóstico de variáveis meteorológicas temperatura, déficit de pressão de vapor do ar, saldo de radiação e velocidade do vento, e da evapotranspiração de referência calculada pelos métodos de Thornthwaite (1948) e de Penman-Monteith (Allen et al., 1998). O desempenho foi avaliado por comparação com dados provenientes de uma estação meteorológica, situada em Piracicaba, São Paulo. A temperatura e o déficit de pressão de vapor do ar foram os elementos melhor prognosticados, com desempenho "muito bom" e "bom", de acordo com o índice de desempenho proposto por Camargo e Sentelhas (1997), para no máximo quatro e três dia de antecedência, respectivamente, durante o período seco. Para o período úmido, somente o prognóstico do déficit de pressão de vapor do ar para o primeiro dia mostrou-se "bom". Os prognósticos de saldo de radiação e velocidade do vento foram ruins para ambos os períodos. Em decorrência do bom desempenho do modelo para prognosticar a temperatura, verificou-se que a estimativa de ETo pelo método de Thornthwaite teve boa concordância com o calculado a partir dos dados da estação meteorológica...

Medições do saldo de radiação em copas de cafeeiros e limeiras ácidas por sistemas de integração espaço-temporal e estimativas por técnicas de modelagem; Measurements of net radiation of the canopy of coffee and acid lime trees in hedgerows by spatiotemporal integration systems and estimates by modelling techniques

Simon, Jones
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 16/06/2010 PT
Relevância na Pesquisa
56.26%
A energia radiante absorvida pelas copas tem aplicação em estudos de fotossíntese e transpiração de plantas arbóreas. Sua determinação não é simples. Nas últimas duas décadas tem sido realizados trabalhos sobre interceptação de radiação por espécies arbóreas isoladas ou em renques, envolvendo tanto radiação de ondas curtas como de ondas longas (saldo de radiação, Rn). Uma técnica de medida de Rn utiliza radiômetros movendo-se em torno da copa de uma árvore (geometria esférica de medida) ou ao longo de copas de um renque (geometria cilíndrica). Uma alternativa é o uso de modelagem físico-matemática para estimativa de Rn, que também exige medidas para testar modelos. Considerando os poucos trabalhos nessa linha de pesquisa, o presente estudo objetivou: a) avaliar o desempenho de sistemas móveis de integração espaçotemporal de medidas de Rn em renque de um cafezal e de um pomar de limeira ácida localizados no Campus Luiz de Queiroz, USP, Piracicaba, SP; b) estabelecer relações do saldo de radiação das copas de cafeeiros (Rnc) e limeiras ácidas (Rnl) com o saldo de radiação de gramado (Rng) e irradiância solar global (Rg); c) avaliar o desempenho de três modelos físicomatemáticos de estimativa de Rn por comparação com as medidas realizadas com varredura da copa pelos saldo-radiômetros movimentando-se ao longo dos renques (geometria cilíndrica de medidas). Os estudos foram realizados nas quatro estações do ano e em três no pomar...

Balanço de radiação e energia da cultura de alface em estufa de polietileno

Frisina, Valéria de Almeida; Escobedo, João Francisco
Fonte: Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Publicador: Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA)
Tipo: Artigo de Revista Científica Formato: 1775-1786
POR
Relevância na Pesquisa
46.37%
Objetivou-se, neste trabalho, determinar os balanços de radiação e energia da cultura de alface (Lactuca sativa, L. cv. Verônica) em estufa de polietileno. O experimento foi realizado em uma estufa tipo túnel alto com cobertura de polietileno (100 mim de espessura) e em uma área externa, ambas com 35 m². Durante o ciclo da cultura, foram monitoradas as radiações global e refletida, saldo de radiação, fluxo de calor no solo e temperatura do ar (seca e úmida) nos dois meios. Utilizou-se um Datalogger que operou na freqüência de 1 Hz, armazenando médias de cinco minutos. A partir das integrações diárias das irradiâncias global (K¯) e refletida (K­), verificou-se que a transmissividade média da radiação global (K¯in / K¯ex) foi aproximadamente constante, em torno de 79,59%, enquanto a razão das radiações refletidas (K­in / K­ex) foi igual a 69,21% com coeficiente de variação de 8,47%. As curvas normalizadas do saldo de radiação de ondas curtas em relação à radiação global (K* / K¯), nos dois meios, mostraram ser aproximadamente constantes no início do ciclo e decrescentes no final. A relação (Rn/ K¯) foi maior no meio externo, em torno de 12%, a partir da fase em que a superfície verde da cultura cobriu o solo. O balanço médio (L*) de radiação de ondas longas foi maior no exterior...

Influência da acurácia de instrumentos de medidas na comparação de métodos de estimativa da evapotranspiração de referência

Turco, José Eduardo Pitelli; Perecin, Dilermando; Pinto Jr., Dorival Leão
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 63-80
POR
Relevância na Pesquisa
46.17%
The aim of this investigation was to evaluate four reference methods to estimate evapotranspiration (Makkink, Hargreaves, Class A pan and Radiation), compared tb Penman-Monteith method, that is considered standard by the Food and Agricultural Organization of the United Nations (FAO). Errors due to variable measurements in the reference evapotranspiration estimate were taken into consideration. The research was developed in an experimental area of the Department of Rural Engieering of the School of Agricultural and Veterinarian Sciences, Campus of Jaboticabal, São Paulo State University. An automated weather station was used and it was equipped with sensors to measure global and net radiation, temperature, relative humidity, and wind speed. The aftermath showed a better adjustment to Hargreaves. Makkink, Class A pan and Radiation methods are different from Penman-Monteith, therefore, they cannot be compared. To evaluate methods to estimate evapotranspiration and avoid possible evaluation errors, ETo estimate errors must be considered.

Radiation and energy balance of lettuce culture inside a polyethylene greenhouse

Frisina,Valéria de Almeida; Escobedo,João Francisco
Fonte: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira Publicador: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/1999 EN
Relevância na Pesquisa
56.38%
The objective of this paper was to describe the radiation and energy balance, during the lettuce (Lactuca sativa, L. cv. Verônica) crop cycle inside a polyethylene greenhouse. The radiation and energy balance was made inside a tunnel greenhouse with polyethylene cover (100 mum) and in an external area, both areas with 35 m². Global, reflected and net radiation, soil heat flux and air temperature (dry and humid) were measured during the crop cycle. A Datalogger, which operated at 1 Hz frequency, storing 5 minutes averages was utilized. The global (K¯) and reflected (K­) radiations showed that the average transmission of global radiation (K¯in / K¯ex) was almost constant, near to 79.59%, while the average ratio of reflected radiation (K­in / K­ex) was 69.21% with 8.47% standard-deviation. The normalized curves of short-wave net radiation, in relation to the global radiation (K*/ K¯), found for both environments, were almost constant at the beginning of cycle; this relation decreased in the final stage of culture. The normalized relation (Rn/ K¯) was bigger in the external area...

Seasonality of net radiation in two sub-basins of Paracatu by the use of modis sensor products

Lima,Evaldo de P.; Sediyama,Gilberto C.; Silva,Bernardo B. da; Gleriani,José M.; Soares,Vicente P.
Fonte: Associação Brasileira de Engenharia Agrícola Publicador: Associação Brasileira de Engenharia Agrícola
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2012 EN
Relevância na Pesquisa
46.29%
The net radiation (Rn) represents the main source of energy for physical and chemical processes that occur in the surface-atmosphere interface, and it is used for air and soil heating, water transfer, in the form of vapor from the surface to the atmosphere, and for the metabolism of plants, especially photosynthesis. If there is no record of net radiation in certain areas, the use of information is important to help determine it. Among them we can highlight those provided by remote sensing. In this context, this work aims to estimate the net radiation, with the use of products of MODIS sensor, in the sub-basins of Entre Ribeiros creek and Preto River, located between the Brazilian states of Goiás and Minas Gerais. The SEBAL (Surface Energy Balance Algorithm for Land) was used to obtain the Rn in four different days in the period of July to October, 2007. The Rn results obtained were consistent with others cited in the literature and are important because the orbital information can help determine the Rn in areas where there are not automatic weather stations to record the net radiation.

Radiation balance of coffee hedgerows

Angelocci,Luiz R.; Marin,Fábio R.; Pilau,Felipe G.; Righi,Evandro Z.; Favarin,José L.
Fonte: Departamento de Engenharia Agrícola - UFCG Publicador: Departamento de Engenharia Agrícola - UFCG
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2008 EN
Relevância na Pesquisa
56.29%
The radiation balance of hedgerows is an important variable in studies of mass and energy exchanges between parcial ground cover crops and the atmosphere. This paper describes a device with eight net radiometers encompassing the plants of a hedgerow. The radiometers were moved along a length of hedgerow, in a continuous and reversible movement. The canopy net radiation in this length (Rnc) was found by integration of the measurements over the notional cylinder formed. The device showed good performance and provided reliable measurements of Rnc of coffee hedgerows, showing itselfto be an useful technique of measurement in field conditions. Good correlations between Rnc and global solar radiation, turfgrass and coffee crop net radiation were found in 15-min, daytime and 24-hr periods, allowing the possibility of estimating Rnc from these simple measurements. Beer’s law was also used to have an independent estimation of Rnc. A good agreement was found between values of Rnc estimated by this law of attenuation and those integrated by the device in periods of 15 min, with overestimation of 10%, whereas for values integrated over daytime periods the agreement was not satisfactory.

Seasonality of net radiation in two sub-basins of Paractu by the use of modis sensor products.

LIMA, E. de P.; SEDYAMA, C. G.; SILVA, B. B. da; GLERIANI, J. M.; SOARES, V. P.
Fonte: Revista Engenharia Agrícola, Jaboticabal, SP, v. 32, n. 6, p. 1184-1196, 2012. Publicador: Revista Engenharia Agrícola, Jaboticabal, SP, v. 32, n. 6, p. 1184-1196, 2012.
Tipo: Artigo em periódico indexado (ALICE) Formato: 12 p.
PT_BR
Relevância na Pesquisa
46.29%
The net radiation (Rn) represents the main source of energy for physical and chemical processes that occur in the surface-atmosphere interface, and it is used for air and soil heating, water transfer, in the form of vapor from the surface to the atmosphere, and for the metabolism of plants, especially photosynthesis. If there is no record of net radiation in certain areas, the use of information is important to help determine it. Among them we can highlight those provided by remote sensing. In this context, this work aims to estimate the net radiation, with the use of products of MODIS sensor, in the sub-basins of Entre Ribeiros creek and Preto River, located between the Brazilian states of Goiás and Minas Gerais. The SEBAL (Surface Energy Balance Algorithm for Land) was used to obtain the Rn in four different days in the period of July to October, 2007. The Rn results obtained were consistent with others cited in the literature and are important because the orbital information can help determine the Rn in areas where there are not automatic weather stations to record the net radiation.; 2012

Caracterização sazonal dos balanços de radiação e energia no Complexo Estuarino-Lagunar Mundaú-Manguaba (Alagoas).; Seasonal characterization of the Net Radiation and energy balance on the Mundaú-Manguaba Estuary-Lagunar Complex (Alagoas).

Santo, Alessandro Renê Souza do Espírito
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
66.29%
The largest Brazilian area of mangroves is the second in the world and the first of th Americas. The knowledge of interaction this ecosystem with the atmosphere is important, because haven‟t a lots of meteorological papers about this subject, especially by the fact that environmental degradation modifies the ecosystem microclimate. Therefore, the study of this environment is essential in it‟s still preserved form. The main objective of this work was to characterize the seasonal variation of the Net Radiation (Rn) and their components in the mangrove of the Mundaú-Manguaba Estuary-Lagunar Complex (Maceió-Al), located in Marechal Deodoro city, inside the Santa Rita Island Environmental Protection Area, situated between latitudes of 9º37‟30‟‟ and 9º47‟30‟‟S and longitudes of 035º45‟00‟‟ e 035º55‟00‟‟W, during the period of October of 2004 to October of 2005. The measures show a great variation between dry and rainy season. The medium maximum values of Rn, is decurrent of the great seasonal variation of the global Radiation (Rg), of which presents a great dependence. It was noticed a seasonal reduction in of 44% Rn, varying of approximately 800 W.m-2...

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
46.19%
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...

Albedo and estimates of net radiation for green beans under polyethylene cover and field conditions

Souza,José Leonaldo de; Escobedo,João Francisco; Tornero,Maria Terezinha Trovareli
Fonte: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira Publicador: Embrapa Informação Tecnológica; Pesquisa Agropecuária Brasileira
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/1999 EN
Relevância na Pesquisa
56.31%
This paper describes the albedo (r) and estimates of net radiation and global solar irradiance for green beans crop (Phaseolus vulgaris L.), cultivated in greenhouse with cover of polyethylene and field conditions, in Botucatu, SP, Brazil (22º 54' S; 48º 27' W; 850 m). The solar global irradiance (Rg) and solar reflected radiation (Rr) were used to estimate the albedo through the ratio between Rr and Rg. The diurnal curves of albedo were obtained for days with clear sky and partially cloudy conditions, for different phenological stages of the crop. The albedo ranged with the solar elevation, the environment and the phenological stages. The cloudiness range have almost no influence on the albedo diurnal amount. The estimation of radiation were made by linear regression, using the global solar irradiance (Rg) and net short-waves radiation (Rc) as independent variables. All estimates of radiation showed better adjustment for specific phenological periods compared to the entire crop growing cycle. The net radiation in the greenhouse has been estimated by the global solar irradiance measured at field conditions.

Measurements of net radiation absorbed by isolated acid lime trees (Citrus latifolia Tanaka).

ANGELOCCI, L. R.; VILLA NOVA, N. A.; COELHO FILHO, M. A.; MARIN, F. R.
Fonte: Journal of Horticultural Science & Biotechnology, v. 79, n. 5, p. 699-703, 2004. Publicador: Journal of Horticultural Science & Biotechnology, v. 79, n. 5, p. 699-703, 2004.
Tipo: Artigo em periódico indexado (ALICE)
EN
Relevância na Pesquisa
46.36%
By using net radiometers mounted on a circular frame rotating around the canopy, measurements of total all-wave radiation absorbed by two 'Tahiti' acid lime trees were carried out in an orchard in Piracicaba, Sao Paulo State, Brazil. The rotating system around the canopy of a tree was formerly idealized and used in New Zealand, allowing integration of all-wave radiation and photosynthetically active radiation absorbed. In an experiment in December 1997, a first device using six net radiometers mounted on a light frame was used. A bigger device, more like the one used in New Zealand, in terms of the number of radiometers and the frame, with a different torque system, was used in another tree on some days from July to September 2000. The performance of both devices is discussed, including the possible error sources when using the first model (1997) and the problems of torque transmission on the second. Despite the lack of a test to check the performance of the device and the problems presented in the year 2000, the results confirm the possibility of providing reliable measurements of the net radiation absorbed by isolated trees. Relations of the net radiation per unit area of projected canopy on the ground were determined with integrated values over different time scales (from 15 min to 24 h). Unique relations between net radiation and incoming solar radiation were obtained for both trees over several time scales. These relations are applicable only to high leaf density conditions and canopy geometry similar to the used in this study.; 2004

Comparison of the performance of net radiation calculation models

Kjaersgaard, Jeppe Hvelplund; Cuenca, Richard Henry; Martínez-Cob, Antonio; Gavilán Zafra, Pedro; Plauborg, F. L.; Mollerup, M.; Hansen, S.
Fonte: Springer Publicador: Springer
Tipo: Artículo Formato: 185371 bytes; application/pdf
ENG
Relevância na Pesquisa
46.37%
The original publication is available at: www.springerlink.com; Daily values of net radiation are used in many applications of crop-growth modeling and agricultural water management. Measurements of net radiation are not part of the routine measurement program at many weather stations and are commonly estimated based on other meteorological parameters. Daily values of net radiation were calculated using three net outgoing long-wave radiation models and compared to measured values. Four meteorological datasets representing two climate regimes, a sub-humid, high-latitude environment and a semi-arid mid-latitude environment, were used to test the models. The long-wave radiation models included a physically based model, an empirical model from the literature, and a new empirical model. Both empirical models used only solar radiation as required for meteorological input. The long-wave radiation models were used with model calibration coefficients from the literature and with locally calibrated ones. A measured, average albedo value of 0.25 was used at the high-latitude sites. A fixed albedo value of 0.25 resulted in less bias and scatter at the mid-latitude sites compared to other albedo values. When used with model coefficients calibrated locally or developed for specific climate regimes...

Evaluating methods of estimating global radiation and vapor pressure deficit using a dense network of automatic weather stations in coastal Brazil.

Almeida, Auro C.; Landsberg, Joe
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
56.31%
A dense network of automatic weather stations (AWS) in eastern Brazil provided the opportunity to test established relationships between global radiation (Rs), photosynthetically active radiation (Rp) and net radiation (Rn). We also examined the variation in vapor pressure deficit (VPD) across the region, and predictions of VPD from temperature data. Predictions of Rs using the MTCLIM package [Agric. For. Meteorol. 93 (1999) 211] accounted for 75% of the variance (r2 = 0.75) in monthly mean measured values but only 62% of the variance in daily values. A procedure described by [Int. J. Bio-meteorol. 44 (2000) 204] was less accurate. Relationships between Rn and Rs gave lower intercept values (indicative of net long-wave fluxes) than expected. Data for a year gave a value of 0.43 for the ratio of Rp to Rs; instrumental problems prevented longer-term comparisons. VPD during daylight hours (VPDday) varied significantly between the northernmost weather station (at 17°26′S) and the most inland, at 17°55′S but at slightly higher altitude (66m compared to 160 m). The r2 values for the linear relationships between maximum and minimum temperatures and VPD day varied across the region, ranging from 0.52 to 0.79. Using a process-based forest production model (3-PG; [For. Ecol. Manage. 95 (1997) 209]) we show that differences in VPD can lead to considerable (28%) reductions in the yield of plantation eucalyptus.

Uso de técnicas de sensoriamento remoto na estimativa do saldo de radiação em Rondônia / Use of techniques of remote sensing in the estimate of the net radiation in Rondônia

Ailton Marcolino Liberato; Fundação Universidade Federal de Rondônia; Bernardo Barbosa da Silva; Unidade Acadêmica de Ciências Atmosférica - UFCG; Fernando Luiz Cardoso; Fundação Universidade Federal de Rondônia
Fonte: EDUFRO Publicador: EDUFRO
Tipo: ; Formato: application/pdf
Publicado em 23/04/2012 PT
Relevância na Pesquisa
46.26%
Propôs-se, neste trabalho, estimar dados de saldo de radiação à superfície terrestre usando-se o sensor Thematic Mapper (TM) do satélite Landsat 5 e compará-lo com dados de uma estação micrometeorológica. A região de estudo esta localizada no estado de Rondônia. Para a realização do estudo obtiveram-se quatro imagens orbitais do satélite Landsat 5 – TM, na órbita 231 e ponto 67, nas datas 13/07/2005, 13/05, 30/06 e 16/07 do ano de 2006, a que correspondem os dias Juliano 194, 133, 181 e 197, respectivamente. As correções geométricas para as imagens foram realizadas e geradas as cartas de saldo de radiação. O algoritmo SEBAL estimou satisfatoriamente os valores de saldo de radiação de superfícies sobre áreas de floresta e pastagem.Palavras-Chave: Sensoriamento remoto. Balanço de radiação. SEBAL.ABSTRACT: This study purpose is to estimate net radiation data at earth surface using the sensor Thematic Mapper (TM) of Landsat 5 and compare it with data from one micrometeorological station. The study area is located in the State of Rondônia. To perform the study four orbital images were obtained from the satellite Landsat 5 - TM  in the orbit 231 and in the row 67...

Parameterization of net radiation in an arid city of northwestern Mexico

García Cueto,Rafael; Santillán Soto,Néstor; Haro Rincón,Zalia; Ojeda Benítez,Sara; Bojórquez Morales,Gonzalo
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
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66.35%
During the process of urbanization, different surface properties significantly alter the radiation balance. This paper attempts to quantify this balance over different surface types in an arid city of northwest Mexico over several days in August 20l1. The albedo of each surface type, as well as local atmospheric properties such as the atmospheric clearness index (K0) and atmospheric emissivity (εatm), were estimated. The surfaces on which measurements were performed were asphalt, concrete, polystyrene painted with white elastomeric paint (PWEP), clay, and grass. It was found that, for a 24-h cycle of measurement, the highest average value of net radiation was for asphalt (146.1 Wm-2), and the lowest average value was for PWEP (33.6 Wm-2). Estimates of albedo values vary depending on the surface, whereas K0 and εatm are dependent on prevailing atmospheric conditions. From these measurements, preliminary statistical models of net radiation as a function of incoming solar radiation and net shortwave radiation were proposed. For each model, the coefficients of determination were higher than 0.97. We discuss the likely implications of the results found for the urban planning of the city.

Measurements of net all-wave radiation at a tropical location, Ile-Ife, Nigeria

AYOOLA,MURITALA A.; SUNMONU,LUKMAN A.; BASHIRU,MUNIRU I.; JEGEDE,OLUWAGBEMIGA O.
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 01/01/2014 EN
Relevância na Pesquisa
56.33%
Hourly averaged net all-wave radiation data spanning a complete three-year period (2010-2012) at a meteorological station located inside the Obafemi Awolowo University campus in Ile-Ife (7.52° N, 4.52° E), Nigeria is presented in this study to investigate its diurnal and seasonal variations. Using a high-sensitivity four-component net radiometer, the data represents so far the most consistent and detailed information available for a tropical location in West Africa. From the dataset, hourly maxima of the net radiation occurred at 14:00 LT (GMT + 1), whose values increased considerably from 337.6 ± 146.4 Wm-2 in July, which is the peak of the wet season, to 441.7 ± 82.4 Wm-2 in March, the end of the dry season. April and October, both of which mark the beginning and end of the raining season at Ile-Ife have recorded the highest values of 584.7 and 612.2 Wm-2, respectively. There was strong intra/inter-seasonal variation observed in the monthly mean values of the net radiation due mainly to the fluctuations in cloudiness and humidity. In the study area, the data indicated a net radiative heating taking place at the surface, whose annual trend follows a bimodal distribution. The present data supports the results published in earlier studies by other authors.