scholarly journals Balanço de radiação, energia e fechamento do balanço em uma floresta prístina na Amazônia oriental.

2020 ◽  
Vol 13 (6) ◽  
pp. 2603
Author(s):  
Wander Luiz Silva Ataide ◽  
Francisco Assis Oliveira ◽  
Carlos Alberto Dias Pinto
Keyword(s):  
Energy Balance ◽  
Eddy Covariance ◽  
Energy Flow ◽  
Balance Sheet ◽  
Radiation Energy ◽  
Primary Forest ◽  
National Forest ◽  
A Value ◽  
Eddy Covariance System ◽  
Pristine Forest

A Floresta Nacional de Caxiuanã, localizada no Estado do Pará, ocupa uma área de 324.060 ha, próxima da baía de Caxiuanã, entre os rios Xingu e Amazonas e compreende aproximadamente 70% do município de Portel e 30% do município de Melgaço. O fluxo de energia foi obtido pelo sistema “Eddy Covariance” localizado a 54 metros de altura. Nota-se uma redução de 10,93% comparando os anos de 2015 (2108,1 mm) e 2016 (2367,8 mm), tendo em vista que a redução da precipitação em determinados sítios é uma consequência das mudanças no balanço de energia e água. O albedo médio do dossel na Flona Caxiuanã foi de 8,5% para ambos os anos avaliados. O fechamento do balanço de energia durante o ano de 2015 e 2016 foi da ordem de 74,83% e 69%, valor este abaixo do que é considerado satisfatório (entre 80 e 90%) como encontrado na literatura. A inclusão do termo (S) na equação melhora substancialmente o fechamento do balanço, principalmente para áreas de florestas primárias devido a quantidade de biomassa. Visando a melhora do fechamento, o fluxo de calor latente foi descartado e então estimado como o resíduo da equação Rn – H – G – S, obtendo um fechamento da ordem de 92,05 e 97,26% para 2015 e 2016.Palavras chave: Eddy covariância, balanço de energia, Caxiuanã, fluxo.                                  Balance of radiation, energy and balance closure in a pristine forest in the eastern Amazon A B S T R A C TThe Caxiuanã National Forest, located in the State of Pará, occupies an area of 324,060 ha, close to Caxiuanã Bay, between the Xingu and Amazonas rivers and comprises approximately 70% of the municipality of Portel and 30% of the municipality of Melgaço. The energy flow was obtained by the “Eddy Covariance” system located 54 meters high. A reduction of 10.93% can be seen comparing the years 2015 (2108.1 mm) and 2016 (2367.8 mm), considering that the reduction of precipitation in certain sites is a consequence of changes in the energy balance and water. The average canopy albedo in Flona Caxiuanã was 8.5% for both years evaluated. The closing of the energy balance during the years 2015 and 2016 was of the order of 74.83% and 69%, a value below what is considered satisfactory (between 80 and 90%) as found in the literature. The inclusion of the term (S) in the equation substantially improves the balance sheet closing, mainly for primary forest areas due to the amount of biomass. In order to improve the closure, the latent heat flow was discarded and then estimated as the residue of the Rn - H - G - S equation, obtaining a closure of the order of 92.05 and 97.26% for 2015 and 2016.Key words: Eddy covariance, energy balance, Caxiuanã, flow.

scholarly journals Energy balance measurements over a banana orchard in the Semiarid region in the Northeast of Brazil

2009 ◽  
Vol 44 (11) ◽  
pp. 1365-1373 ◽  
Author(s):  
Carlos Antonio Costa dos Santos ◽  
Bernardo Barbosa da Silva ◽  
Tantravahi Venkata Ramana Rao ◽  
Christopher Michael Usher Neale
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Eddy Covariance ◽  
Heat Fluxes ◽  
Irrigation District ◽  
Semiarid Region ◽  
Energy Balance Closure ◽  
Wet Season ◽  
Growing Seasons ◽  
Eddy Covariance System

The objective of this work was to evaluate the reliability of eddy covariance measurements, analyzing the energy balance components, evapotranspiration and energy balance closure in dry and wet growing seasons, in a banana orchard. The experiment was carried out at a farm located within the irrigation district of Quixeré, in the Lower Jaguaribe basin, in Ceará state, Brazil. An eddy covariance system was used to measure the turbulent flux. An automatic weather station was installed in a grass field to obtain the reference evapotranspiration (ET0) from the combined FAO-Penman-Monteith method. Wind speed and vapor pressure deficit are the most important variables on the evaporative process in both growing seasons. In the dry season, the heat fluxes have a similar order of magnitude, and during the wet season the latent heat flux is the largest. The eddy covariance system had acceptable reliability in measuring heat flux, with actual evapotranspiration results comparing well with those obtained by using the water balance method. The energy balance closure had good results for the study area, with mean values of 0.93 and 0.86 for the dry and wet growing seasons respectively.

Lysimeter assessment of the Simplified Two-Source Energy Balance model and eddy covariance system to estimate vineyard evapotranspiration

2019 ◽  
Vol 274 ◽  
pp. 172-183 ◽  
Author(s):  
Juan M. Sánchez ◽  
Ramón López-Urrea ◽  
Francisco Valentín ◽  
Vicente Caselles ◽  
Joan M. Galve
Keyword(s):  
Energy Balance ◽  
Eddy Covariance ◽  
Energy Balance Model ◽  
Balance Model ◽  
Eddy Covariance System

scholarly journals Estimating evaporation with thermal UAV data and two-source energy balance models

2016 ◽  
Vol 20 (2) ◽  
pp. 697-713 ◽  
Author(s):  
H. Hoffmann ◽  
H. Nieto ◽  
R. Jensen ◽  
R. Guzinski ◽  
P. Zarco-Tejada ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
High Resolution ◽  
Eddy Covariance ◽  
Land Surface ◽  
Weather Conditions ◽  
Heat Fluxes ◽  
Thermal Camera ◽  
Model Input ◽  
Eddy Covariance Measurements

Abstract. Estimating evaporation is important when managing water resources and cultivating crops. Evaporation can be estimated using land surface heat flux models and remotely sensed land surface temperatures (LST), which have recently become obtainable in very high resolution using lightweight thermal cameras and Unmanned Aerial Vehicles (UAVs). In this study a thermal camera was mounted on a UAV and applied into the field of heat fluxes and hydrology by concatenating thermal images into mosaics of LST and using these as input for the two-source energy balance (TSEB) modelling scheme. Thermal images are obtained with a fixed-wing UAV overflying a barley field in western Denmark during the growing season of 2014 and a spatial resolution of 0.20 m is obtained in final LST mosaics. Two models are used: the original TSEB model (TSEB-PT) and a dual-temperature-difference (DTD) model. In contrast to the TSEB-PT model, the DTD model accounts for the bias that is likely present in remotely sensed LST. TSEB-PT and DTD have already been well tested, however only during sunny weather conditions and with satellite images serving as thermal input. The aim of this study is to assess whether a lightweight thermal camera mounted on a UAV is able to provide data of sufficient quality to constitute as model input and thus attain accurate and high spatial and temporal resolution surface energy heat fluxes, with special focus on latent heat flux (evaporation). Furthermore, this study evaluates the performance of the TSEB scheme during cloudy and overcast weather conditions, which is feasible due to the low data retrieval altitude (due to low UAV flying altitude) compared to satellite thermal data that are only available during clear-sky conditions. TSEB-PT and DTD fluxes are compared and validated against eddy covariance measurements and the comparison shows that both TSEB-PT and DTD simulations are in good agreement with eddy covariance measurements, with DTD obtaining the best results. The DTD model provides results comparable to studies estimating evaporation with similar experimental setups, but with LST retrieved from satellites instead of a UAV. Further, systematic irrigation patterns on the barley field provide confidence in the veracity of the spatially distributed evaporation revealed by model output maps. Lastly, this study outlines and discusses the thermal UAV image processing that results in mosaics suited for model input. This study shows that the UAV platform and the lightweight thermal camera provide high spatial and temporal resolution data valid for model input and for other potential applications requiring high-resolution and consistent LST.

scholarly journals Emissions of carbon dioxide and methane from fields fertilized with digestate from an agricultural biogas plant

2018 ◽  
Vol 32 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Robert Czubaszek ◽  
Agnieszka Wysocka-Czubaszek
Keyword(s):  
Carbon Dioxide ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Eddy Covariance ◽  
Soil Structure ◽  
Mineral Fertilizers ◽  
Gas Emissions ◽  
Gas Fluxes ◽  
Biogas Plants ◽  
Eddy Covariance System

AbstractDigestate from biogas plants can play important role in agriculture by providing nutrients, improving soil structure and reducing the use of mineral fertilizers. Still, less is known about greenhouse gas emissions from soil during and after digestate application. The aim of the study was to estimate the emissions of carbon dioxide (CO2) and methane (CH4) from a field which was fertilized with digestate. The gas fluxes were measured with the eddy covariance system. Each day, the eddy covariance system was installed in various places of the field, depending on the dominant wind direction, so that each time the results were obtained from an area where the digestate was distributed. The results showed the relatively low impact of the studied gases emissions on total greenhouse gas emissions from agriculture. Maximum values of the CO2and CH4fluxes, 79.62 and 3.049 µmol s−1m−2, respectively, were observed during digestate spreading on the surface of the field. On the same day, the digestate was mixed with the topsoil layer using a disc harrow. This resulted in increased CO2emissions the following day. Intense mineralization of digestate, observed after fertilization may not give the expected effects in terms of protection and enrichment of soil organic matter.

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