scholarly journals Avaliação da Evapotranspiração de Pastagem pelo Método do Domo (Evaluation of Grassland Evapotranspiration by Dome Method)

2014 ◽  
Vol 7 (4) ◽  
pp. 716
Author(s):  
Irami Buarque Amazonas ◽  
Antônio Celso Dantas Antonino ◽  
Willames Albuquerque Sores ◽  
José Romualdo Sousa Lima ◽  
Suzana Maria Gico Lima Montenegro
Keyword(s):  
Experimental Data ◽  
Energy Balance ◽  
Bowen Ratio ◽  
Botanical Garden ◽  
Ratio Method ◽  
Satisfactory Performance ◽  
De Se ◽  
Para Determinar ◽  
The Town ◽  
Semi Arid

A região semiárida nordestina necessita de formas alternativas confiáveis economicamente e viáveis de se estimar a evaporação (E) ou a evapotranspiração (ET), uma vez que apresenta um regime de chuvas irregular e a ET se constitui na principal perda de água no sistema solo-planta-atmosfera. Dentre os vários métodos de se determinar a ET, o domo tem sido comparado com outros métodos, apresentando desempenho satisfatório e, por ser mais barato do que os demais, pode se tornar uma alternativa viável para medidas rápidas e pontuais. O domo consiste em uma cúpula de acrílico colocada sobre o solo, onde se determina a E ou ET a partir de medidas de temperatura e umidade no seu interior. Neste trabalho o domo foi usado para determinar a ET de uma pastagem, no município de São João-PE, e os resultados foram confrontados com os obtidos pelo balanço de energia-razão de Bowen. Verificou-se que o método do domo apresentou resultados satisfatórios na determinação da ET, sendo a média diária de 3,33 e 4,05 mm d-1, obtidas pelo domo e pela razão de Bowen, respectivamente. A metodologia do domo possui a desvantagem de não ser automatizada e subestimar a ET nos horários de maior incidência de radiação.    A B S T R A C T The semi-arid northeastern need of alternative reliable and economically feasible to estimate evaporation (E) or evapotranspiration (ET), since it presents an irregular rainfall and ET constitutes the main loss of water in the soil-plant-atmosphere. Among the various methods of determining the ET, the dome has been compared with other methods, showing satisfactory performance, and because it is cheaper than the others, it can become a viable alternative for rapid and punctual measures. The dome consists of an acrylic dome placed over the soil, where it determines the E or ET from measurements of temperature and humidity inside. In this work, the dome was used to determine the ET of grassland in the town of São João, in the Pernambuco state, and the results were compared with experimental data obtained from the energy balance-Bowen ratio method. It has been found that the method of the dome was satisfactory in determining ET of the grassland and the average daily ET was 3.33 and 4.05 mmd-1, obtained by the dome and by Bowen ratio, respectively. The methodology of the dome has the disadvantage of not being automated and underestimates the evapotranspiration in times of highest incidence of radiation. Keywords: Native fruits, Flora of Brazil, Phenology, Botanical Garden 

scholarly journals Quantification and Mapping of Satellite Driven Surface Energy Balance Fluxes in Semi-Arid to Arid Inter-Mountain Region

2020 ◽  
Vol 12 (24) ◽  
pp. 4019
Author(s):  
Bibek Acharya ◽  
Vivek Sharma ◽  
James Heitholt ◽  
Daniel Tekiela ◽  
Fabian Nippgen
Keyword(s):  
Land Use ◽  
Energy Balance ◽  
Irrigation System ◽  
Groundwater Resources ◽  
Regional Scale ◽  
Bowen Ratio ◽  
Soil Heat Flux ◽  
Irrigation Districts ◽  
Intermountain Region ◽  
Semi Arid

Crop evapotranspiration (ETc) estimates, on a regional scale, hold enormous potential in managing surface and groundwater resources. This is particularly important for the headwater state of Wyoming, which provides water to found major river basins of the US. In this study, METRIC (Mapping evapotranspiration at high resolution with internalized calibration), a satellite-based image processing model, was used to map and quantify daily, monthly, and seasonal ETc and other energy balance fluxes, i.e., net radiation (Rn), sensible heat (H), and soil heat flux (G) dynamics for different land-use classes. Monthly and seasonal ETc estimated were further used to approximate regional water consumption patterns for different land-use types for nine irrigation districts in semi-arid to arid intermountain region of Big Horn Basin (BHB), Wyoming. The validation of METRIC retrievals against Bowen ratio energy balance system (BREBS) fluxes measured over three vegetative surfaces, viz. sugar beet in 2017, dry bean in 2018, and barley in 2019, indicated high accuracy. The pooled correlation observed between estimated (pooled) and measured instantaneous fluxes had R2 values of 0.91 (RMSE = 0.08 mm h−1, NSE = 0.91), 0.81 (RMSE = 49.6 Wm−2, NSE = 0.67), 0.53 (RMSE = 27.1 Wm−2, NSE = 0.53), and 0.86 (RMSE = 59.2 Wm−2, NSE = 0.84) for ETc, Rn, G, and H, respectively. The biggest discrepancy between measured and estimated monthly ETc values was observed during times when BREBS flux tower footprint was devoid of any crops or the crops at footprint were not actively transpiring. Validation results improved when comparisons were made on monthly scales with METRIC underestimating growing season ETc in the range between 3.2% to 6.0%. Seasonal ETc by land-use type showed significant variation over the study area where crop ETc was 52% higher than natural vegetation ETc. Furthermore, it was found that, in the arid to semi-arid intermountain region of Wyoming, the contribution of irrigation to total seasonal ETc varied in the range of 73–81% in nine irrigation districts that fall within the study area. The high relative contribution of irrigation highlights the importance of identifying and quantifying ETc for improved management in irrigation system design and water allocation.

scholarly journals A field study on Ground Energy Balance calculation for typical communities in South China

2020 ◽  
Vol 172 ◽  
pp. 25003
Author(s):  
Riyi Li ◽  
Yufeng Zhang ◽  
Chongyun Huang ◽  
Chundian He
Keyword(s):  
Energy Balance ◽  
Solar Radiation ◽  
Latent Heat ◽  
South China ◽  
Convective Heat Transfer Coefficient ◽  
Bowen Ratio ◽  
Ground Temperature ◽  
Ratio Method ◽  
Subtropical Climate ◽  
Ground Energy

Urban heat island (UHI) greatly influences human health, comfort and building energy. The ground temperature plays an important role in understanding UHI, and the method based on the ground energy balance (GEB) is fundamental in the predictions of urban ground temperature and UHI. South China is fast developed and highly urbanized, with special humid subtropical climate and particular urban design characteristics. Although amounts of methods or formulas have been previously proposed for urban GEB calculation, few of them has been testified in field in South China. In this study, two typical urban communities in South China in the aligned and enclosed layout were measured during the summer sunny days in Aug. 2017, with the focus on incident solar radiation, sensible heat, and latent heat of the ground. The measured data were compared with the calculated ones by various methods. The results show that the two calculation methods, i.e., with and without reflections, showed comparable performances (difference on RMSE 3-13 W/m2) in the prediction of solar radiation incident into the community ground. The previously proposed formulas performed poorly in the prediction of surface convective heat transfer coefficient for the community hard pavement, and the power function regressed by using the measuring data performed well, with the air speed at the reference height of 0.13 m as variable and R2 of 0.74. The Bowen ratio method performed better in the prediction of latent heat for the community permeable sidewalk, with RMSE of 156 W/m2 and the consistency index of 0.93. This study provides the field evidences and reliable methods for urban GEB calculation, and potentially contributes to the UHI prediction and mitigation in South China.

scholarly journals Assessment of daily actual evapotranspiration with SEBAL and S-SEBI algorithms in cotton crop

2010 ◽  
Vol 25 (3) ◽  
pp. 383-392 ◽  
Author(s):  
Carlos Antonio Costa dos Santos ◽  
Bergson Guedes Bezerra ◽  
Bernardo Barbosa da Silva ◽  
Tantravahi Venkata Ramana Rao
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Iterative Process ◽  
Arid Regions ◽  
Bowen Ratio ◽  
The State ◽  
Actual Evapotranspiration ◽  
Cotton Crop ◽  
Semi Arid

The main objective of this study is to assess the daily ET accuracy obtained by remote sensing algorithms in comparison with measurements in situ. The experiment was conducted in the State of Ceará, Brazil, in a cotton experimental field of EMBRAPA using Bowen ratio measurements to obtain the energy balance components. SEBAL and S-SEBI algorithms were used with four TM Landsat - 5 images of 2005, in order to determine the actual evapotranspiration of cotton crop. The comparison between the estimated values by remote sensing algorithms and the measured values in situ showed that the methods (SEBAL and S-SEBI) presented satisfactory results. The S-SEBI algorithm is an important tool to be applied in ET analysis of semi-arid regions, due its practicability to solve the energy balance and its processing is simpler than SEBAL algorithm which needs the solution of an iterative process.

Long-term energy balance measurements at three different mountain permafrost sites in the Swiss Alps

2020 ◽  
Author(s):  
Martin Hoelzle ◽  
Christian Hauck ◽  
Jeannette Noetzli ◽  
Cécile Pellet ◽  
Martin Scherler
Keyword(s):  
Energy Balance ◽  
Air Temperature ◽  
Bowen Ratio ◽  
Heat Fluxes ◽  
Swiss Alps ◽  
Ratio Method ◽  
Fine Grained ◽  
Mountain Permafrost ◽  
Ice Content

<p>The surface energy balance is one of the most important influencing factors for the ground thermal regime. It is therefore crucial to understand the interactions of the individual heat fluxes at the surface and within the subsurface layers as well as their relative impacts. A unique set of high-altitude meteorological measurements has been analysed to determine the energy balance at three mountain permafrost sites in the Swiss Alps, where data is being collected since the late 1990s in collaboration with the Swiss Permafrost Monitoring (PERMOS). The three stations have a standardized equipment with sensors for four-component radiation, air temperature, humidity, wind speed and direction as well as ground temperatures and snow height. The three sites differ considerably by their surface and ground material composition ranging from a coarse blocky active layer above ice supersaturated permafrost at rock glacier Murtèl-Corvatsch to deeply weathered micaceous shales, which are covered by fine grained debris of sandy and silty material with a low ice content at the Northern slope of Schilthorn summit. The third site at the Stockhorn plateau shows intermediate ice contents and heterogeneous surface conditions with medium-size debris, fine grained material and outcropping bedrock. Ice content estimation and general ground characterisation are based on geophysical surveying and borehole drilling.</p><p> </p><p>The energy fluxes are calculated based on around two decades of field measurements. While the determination of the radiation budget and the ground heat flux is comparatively straightforward (by the four-component radiation sensor and thermistor measurements within the boreholes, respectively), larger uncertainties exist for the determination of sensible and latent turbulent heat fluxes. They are therefore determined on the one hand by the bulk aerodynamic method using the bulk Richardson number to describe the stability of the surface layer relating the relative effects of buoyancy to mechanical forces and on the other hand by the bowen ratio method.</p><p> </p><p>Results show that mean air temperature at Murtèl-Corvatsch (1997–2018, elevation 2600 m asl.) is –1.66°C and has increased by about 0.7°C during the observation period. The Schilthorn (1999–2018, elevation 2900 m asl.) site shows a mean air temperature of –2.48°C with a mean increase of 1.0°C and the Stockhorn (2003–2018, elevation 3400 m asl.) site shows lower air temperatures with a mean of –5.99°C with an increase of 0.6°C. Measured net radiation, as the most important energy input at the surface, shows substantial differences with mean values of 33.41 Wm<sup>-2</sup> for Murtèl-Corvatsch, 40.65 Wm<sup>-2</sup> for Schilthorn and 24.88 Wm<sup>-2</sup> for Stockhorn. The calculated turbulent fluxes show values of around 7 to 12 Wm<sup>-2</sup> using the bowen ratio method and 8 to 18 Wm<sup>-2</sup> using the bulk method at all sites. Large differences are observed regarding the energy used for melting of the snow cover: at Schilthorn a value of 12.41 Wm<sup>-2</sup>, at Murtèl-Corvatsch of 7.31 Wm<sup>-2</sup> and at Stockhorn of 3.46 Wm<sup>-2</sup> is calculated reflecting the differences in snow height at the three sites.</p>

scholarly journals Energy and Water Balances of a Bog in Central Sweden

1997 ◽  
Vol 28 (4-5) ◽  
pp. 263-272 ◽  
Author(s):  
Mattias Phersson ◽  
Ola Pettersson
Keyword(s):  
Energy Balance ◽  
Groundwater Level ◽  
Evaporation Rate ◽  
Bowen Ratio ◽  
Groundwater Table ◽  
Ratio Method ◽  
Considerable Part ◽  
Balance Study ◽  
Energy Balances ◽  
Low Precipitation

Fens and bogs represent a considerable part of the boreal forest area of Scandinavia, but have not received much attention. To understand their role in the water and energy balances an investigation was carried out during the spring and summer of 1994 as a part of the NOPEX program. Groundwater level, precipitation and energy budget parameters were measured at the Ryggmossen bog, 35 km Northwest of Uppsala. The evaporation (10 min averages) was determined by the Energy Balance Bowen Ratio method and a reference evaporation (10 min averages) was also calculated according to Penman (1948). The results of the evaporation and energy balance study showed that the actual evaporation was 60% of the reference evaporation and that the evaporation rate was dependent on the groundwater depth. The weather during the period was warm with extremely low precipitation. The evaporation therefore decreased during the summer in response to the increased depth to the groundwater table. A relation was found between the groundwater level recession rate and the evaporation rate. The albedo increased during the summer and any occasional decrease could be attributed to individual rain storms.

Envelhecimento ativo e promoção da empregabilidade entre os cidadãos seniores

2014 ◽  
Author(s):  
Ana Barroca ◽  
Gonçalo Meireles ◽  
Catarina Neto
Keyword(s):  
De Se ◽  
Recursos Humanos ◽  
Para Determinar

A crescente consciência da necessidade de expandir a participação dos cidadãos mais velhos no mercado de trabalho, considerando o contexto de alterações demográficas, não é, no entanto, suficiente para garantir o crescimento da mão de obra qualificada. Existe assim paralelamente uma necessidade de maximizar a utilização do trabalho tal. A Estratégia Europa 2020 enfatiza a necessidade de combinar o desenvolvimento de competências de trabalho ao longo da vida com melhor adequação entre a oferta e a procura, no mercado de trabalho. Um artigo recente do governo britânico defendia que: “Não há relação automática entre as competências e a produtividade. Criticamente importante é como as empresas realmente usam as competências da sua força de trabalho”. O relatório da Comissão Europeia “Novas competências para novos empregos” refere igualmente que pode haver a necessidade de envolver intermediários-chave, como entidades de educação e formação e prestadores de serviços de emprego, para determinar como melhorar a utilização das competências em contexto de trabalho, bem como melhorar as redes de cooperação entre empregadores para partilha de boas práticas na gestão das competências em contexto de trabalho. Investigações anteriores promovidas pela União Europeia sugerem que é mais fácil aumentar o emprego dos trabalhadores mais idosos, de ambos os sexos, se os empregadores e empregados estiverem convencidos das vantagens de estender as relações de trabalho atuais e não se couber ao Estado procurar novos empregos para os trabalhadores idosos fora do mercado de trabalho. A superação dos desafios económicos, dos desafios relacionados com o emprego e dos desafios sociais resultantes das alterações demográficas deverá constituir uma prioridade essencial atendendo ao aumento significativo da percentagem de idosos na população e à correspondente redução da força de trabalho. Os governos e as empresas têm de se adaptar à evolução da força de trabalho disponível e dar resposta à necessidade de disponibilizar produtos e serviços adequados e acessíveis e de adaptar as condições de trabalho e de vida ao envelhecimento da população. O aumento da taxa de emprego de todas as pessoas em idade ativa constitui um objetivo político essencial para os Estados-Membros, tal como referido nos grandes objetivos da Estratégia "Europa 2020" nos domínios do emprego e da redução da pobreza e da exclusão social. A sustentabilidade da taxa de emprego dos trabalhadores mais velhos depende da intervenção do Estado mas, essencialmente, do papel do setor empresarial privado e da iniciativa dos trabalhadores. Ao setor empresarial privado compete definir estratégias empresariais e estratégias de gestão de recursos humanos que não definam a idade como “handicap” à produtividade dos respetivos trabalhadores e, por consequência, ameaça à sua competitividade e criar condições para um melhor desempenho profissional dos seus trabalhadores dentro das respetivas fases do seu ciclo de vida. Aos trabalhadores compete gerir a sua vida profissional, investir na qualificação e desenvolvimento de competências necessárias aos diferentes momentos do seu percurso profissional.

PLURALIZAÇÃO ORDENATIVA E CONFLITOS CONSTITUCIONAIS: NOVOS PARADIGMAS DE ESTABILIZAÇÃO NORMATIVA NOS SISTEMAS TRANSNACIONAIS

2019 ◽  
Vol 22 (36) ◽  
Author(s):  
Rafael Freitas ◽  
Luis Cláudio Martins de Araújo
Keyword(s):  
De Se ◽  
Para Determinar

O presente artigo se estrutura, a partir da apresentação do problema ocasionado pela insuficiência dos modelos tradicionais para a solução dos conflitos constitucionais globais, diante da atual fragmentação do sistema global e crescente pluralização de ordens jurídicas, propondo a formulação de um modelo de análise, no qual se permita gerar uma contribuição para a justificação de um novo paradigma de estabilização transnacional do sistema constituciona global, sob a égide de parâmetros recursivos e circulares, dada a necessidade de se construir parâmetros e diretrizes de uma agenda cooperativa nas sociedades multifacetárias, a partir da integração relativamente estável dos sistemas constitucionais globais.  A metodologia do trabalho se orientará através de análise bibliográfica, por meio de referências teóricas fundamentais sobre o tema “transconstitucionalismo”, a fim de se estabelecer uma teoria que compreenda mecanismos e instrumentos capazes de aperfeiçoar o exercício de mecanismos de entrelaçamento constitucional, com a estabilização transnacional do sistema constitucional global nas sociedades multifacetárias. Da mesma forma, será necessário tomar como referencial, a necessidade de criação de uma rede de reciprocidade arquitetada a partir de um consenso sobreposto por meio de um procedimento democrático compatível com as diferentes concepções de justiça de uma sociedade complexa. Assim, irá se procurar contextualizar esse fenômeno, a partir da intensificação de um diálogo pluralista e participativo, para determinar a legitimação do sistema constitucional nas sociedades multifacetárias, dada a idealização de um modelo de direito constitucional global de colisões (verfassungskollisionsrecht) construído a partir da fragmentação sistêmica.

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