Bowen ratio determination of sensible and latent heat fluxes in a humid tropical environment at Ile- Ife, Nigeria

The Bowen ratio energy balance (BREB) method is the most widely used for estimating the fluxes of sensible heat and latent heat near the surface largely because of its conceptual simplicity and the robustness of instrumentation required. We have adopted the same technique here to study partitioning of measured available energy (difference of net radiation and soil heat flux) over bare soil at a humid tropical location in Ile-Ife, Nigeria (7° 33' N, 4° 34' E) between 7 and 10 March, 1999. Results obtained of the diurnal variations of the both fluxes in relation to the changing surface conditions (case studies) are quite satisfactory. For dry days, the sensible heat flux is comparatively of the same magnitude as the latent heat flux but it is less, about 10-60% for the wet surface conditions. It is clear from the present study that for the tropical forest zone, evaporation is the next important factor after radiation in the energy balance due to the humid conditions that usually prevail. Except for the few instances when very weak gradients exist, particularly of moisture, during transition periods (at sunrise or sunset), the technique has worked satisfactorily for day as well as night time periods regardless of prevailing weather conditions.

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Energy balance in a renewal sugarcane area with fallow period and soybean cultivation

Ciência e Natura ◽

10.5902/2179460x53222 ◽

2020 ◽

Vol 42 ◽

pp. e39

Author(s):

Rubmara Ketzer Oliveira ◽

Luciano Sobral Fraga Junior ◽

Larissa Brêtas Moura ◽

Debora Regina Roberti ◽

Felipe Gustavo Pilau

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Latent Heat ◽

Latent Heat Flux ◽

Sensible Heat Flux ◽

Heat Fluxes ◽

Rainfall Regime ◽

Sensible Heat ◽

Energy Fluxes ◽

Fallow Period

Brazil is the main sugarcane producer in the world, which is intended for various purposes, from food to power generation. Soybean cultivation in areas of sugarcane under renewal has been growing progressively in Brazil. Quantifying energy fluxes at different stages of this process is essential for better management. The work was carried out in Piracicaba city, with the objective of analyzing the behavior of energy fluxes and the closing of the energy balance in a sugarcane renewal area with a fallow period followed by soybean cultivation. The latent and sensitive heat fluxes were obtained with the “Eddy covariance” method. The closing of the energy balance in the fallow period with straw-covered uncovered and soybean-cultivated soil presented a correlation coefficient of 0.88, 0.78 and 0.71, respectively. In the period without cultivation, the sensible heat flux was predominant in relation to the latent heat flux, varying according to the rainfall regime. The presence of straw under the soil in the fallow period affected the latent heat flux. With soybean cultivation, the latent heat flux surpassed the sensible heat flux.

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DYNAMICS OF HEAT FLUXES BY BOWEN AND MATMNXFLX AND NOAH FLDAS PRODUCTS IN THE PANTANAL OF MATO GROSSO.

Raega - O Espaço Geográfico em Análise ◽

10.5380/raega.v46i3.66981 ◽

2019 ◽

Vol 46 (3) ◽

pp. 07

Author(s):

Leilane Gomes Duarte ◽

Kelly Souza Romera ◽

Marlus Sabino ◽

Leone Francisco Amorim Curado ◽

Rafael Da Silva Palácios ◽

...

Keyword(s):

Heat Flux ◽

Latent Heat ◽

Sensible Heat Flux ◽

Bowen Ratio ◽

Absolute Error ◽

Soil Heat Flux ◽

Heat Fluxes ◽

Sensible Heat ◽

Seasonal Behavior ◽

Mato Grosso

This paper aimed to analyze the dynamics of the energy budget components: latent heat flux (LE), sensible heat flux (H) and soil heat flux (G), in the Mato Grosso Pantanal. The estimates of LE, H, and G were obtained by the Bowen ratio methods, using data from the micrometeorological tower located in the Baía das Pedras Park of SESC-Pantanal Ecological Resort, for the years 2011 to 2013. The normality of the variables Rn, LE, H and G, were tested by Kolmogorov-Smirnov test at 5% significance, and the seasonal differences of the fluxes were verified by the KruskalWallis test, α = 0.05. LE and H data from the remote sensing products MATMNXFLX and FLDAS_NOAH of the MERRA model was also acquired, and their comparison with the tower data was performed by the statistics of Spearman correlation (r), Mean Absolute Error (MAE), Root Mean Squared Erro (RMSE), bias, and Willmott's Concordance Index (d). It was observed that most of the available energy is used for evapotranspiration (latent heat), followed by sensible heat and soil heat flux. In the rainy season there is an increase in the partition of LE and G and reduction of H. Only the estimates of LE of MATMNXFLX and FLDAS_NOAH products correlate with the data observed in the meteorological tower. It is concluded that the energy partitions have a seasonal behavior and that the MATMNXFLX and FLDAS_NOAH products, after being calibrated, can be used to estimate LE in the Mato Grosso Pantanal.

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ESTUDO DO CALOR SENSÍVEL E LATENTE OBTIDOS POR INTERMÉDIO DA RAZÃO DE BOWEN EM UMA CULTURA DE SOJA IRRIGADA.

Irriga ◽

10.15809/irriga.2007v12n3p281-296 ◽

2007 ◽

Vol 12 (3) ◽

pp. 281-296 ◽

Cited By ~ 1

Author(s):

Edemo João Fernandes

Keyword(s):

Heat Flux ◽

Latent Heat ◽

Sensible Heat Flux ◽

Bowen Ratio ◽

Vertical Displacement ◽

Heat Fluxes ◽

Sensible Heat ◽

Soybean Crop ◽

The Mean ◽

Soil Water Conditions

ESTUDO DO CALOR SENSÍVEL E LATENTE OBTIDOS POR INTERMÉDIO DA RAZÃO DE BOWEN EM UMA CULTURA DE SOJA IRRIGADA. Edemo João FernandesDepartamento de Engenharia Rural, Universidade Estadual Paulista, Campus de Jaboticabal, SP,[email protected] 1 RESUMO O experimento teve por objetivo estudar as variações dos fluxos de calor sensível e latente sobre uma cultura de soja irrigada, obtidos com a utilização da razão de Bowen. Foi construída uma estação micrometeorológica, com deslocamento vertical dos sensores para manter o mesmo nível de medidas acima da cobertura vegetal. A estação foi instalada na parte central da parcela, distante130 mda margem principal da direção dos ventos predominantes. Os fluxos foram calculados em função dos gradientes verticais de temperaturas determinadas a 0,15 e1,15 mde altura acima da cultura de soja. Em condições de bom suprimento de água e com a cultura cobrindo totalmente o solo o fluxo de calor latente é o maior consumidor da energia disponível na vegetação. O fluxo de calor sensível foi maior no início do desenvolvimento da cultura, quando o índice de área foliar foi menor. A cobertura vegetal é preponderante no consumo da energia disponível na vegetação em forma de calor latente. UNITERMOS: fluxos de calor, radiação líquida, temperatura do ar. FERNANDES, E. J. F. STUDY OF SENSIBLE AND LATENT HEAT OBTAINED BY BOWEN RATIO FROM IRRIGATED SOYBEAN CROP 2 ABSTRACT The goal of this experiment was to study the latent and sensible heat variation determined by Bowen ratio from an irrigated soybean crop. A micrometeorological station with vertical displacement was constructed to maintain the same level of all measures over the canopy. The station was installed in the center of the crop, and it was over130 maway from the main edge of the predominant wind direction. Fluxes were calculated by vertical temperature gradient determined at 0.15 and1.15 mover the canopy. The latent heat flux was the mean energy consumer when the canopy covered the soil totally, and there were good soil water conditions. The sensible heat flux was greater when the soil was not totally covered by the canopy. The canopy was essential on the amount of latent heat dissipated by the crop. KEYWORDS: heat fluxes, net radiation, air temperature.

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Ability of a soil–vegetation–atmosphere transfer model and a two-source energy balance model to predict evapotranspiration for several crops and climate conditions

Hydrology and Earth System Sciences ◽

10.5194/hess-23-5033-2019 ◽

2019 ◽

Vol 23 (12) ◽

pp. 5033-5058

Author(s):

Guillaume Bigeard ◽

Benoit Coudert ◽

Jonas Chirouze ◽

Salah Er-Raki ◽

Gilles Boulet ◽

...

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Latent Heat ◽

Sensible Heat Flux ◽

Heat Fluxes ◽

Balance Model ◽

Transfer Model ◽

Climate Conditions ◽

Crop Types ◽

Svat Model

Abstract. The heterogeneity of Agroecosystems, in terms of hydric conditions, crop types and states, and meteorological forcing, is difficult to characterize precisely at the field scale over an agricultural landscape. This study aims to perform a sensitivity study with respect to the uncertain model inputs of two classical approaches used to map the evapotranspiration of agroecosystems: (1) a surface energy balance (SEB) model, the Two-Source Energy Balance (TSEB) model, forced with thermal infrared (TIR) data as a proxy for the crop hydric conditions, and (2) a soil–vegetation–atmosphere transfer (SVAT) model, the SEtHyS model, where hydric conditions are computed from a soil water budget. To this end, the models' skill was compared using a large and unique in situ database covering different crops and climate conditions, which was acquired over three experimental sites in southern France and Morocco. On average, the models provide 30 min estimations of latent heat flux (LE) with a RMSE of around 55 W m−2 for TSEB and 47 W m−2 for SEtHyS, and estimations of sensible heat flux (H) with a RMSE of around 29 W m−2 for TSEB and 38 W m−2 for SEtHyS. A sensitivity analysis based on realistic errors aimed to estimate the potential decrease in performance induced by the spatialization process. For the SVAT model, the multi-objective calibration iterative procedure (MCIP) is used to determine and test different sets of parameters. TSEB is run with only one set of parameters and provides acceptable performance for all crop stages apart from the early growing season (LAI < 0.2 m2 m−2) and when hydric stress occurs. An in-depth study on the Priestley–Taylor key parameter highlights its marked diurnal cycle and the need to adjust its value to improve flux partitioning between the sensible and latent heat fluxes (1.5 and 1.25 for France and Morocco, respectively). Optimal values of 1.8–2 were highlighted under cloudy conditions, which is of particular interest due to the emergence of low-altitude drone acquisition. Under developed vegetation (LAI > 0.8 m2 m−2) and unstressed conditions, using sets of parameters that only differentiate crop types is a valuable trade-off for SEtHyS. This study provides some scientific elements regarding the joint use of both approaches and TIR imagery, via the development of new data assimilation and calibration strategies.

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Comparison of turbulent structures and energy fluxes over exposed and debris-covered glacier ice

Journal of Glaciology ◽

10.1017/jog.2020.23 ◽

2020 ◽

Vol 66 (258) ◽

pp. 543-555 ◽

Cited By ~ 2

Author(s):

Lindsey Nicholson ◽

Ivana Stiperski

Keyword(s):

Heat Flux ◽

Latent Heat ◽

Similarity Theory ◽

Sensible Heat Flux ◽

Heat Fluxes ◽

Temperature Fields ◽

Sensible Heat ◽

Energy Fluxes ◽

Glacier Surface ◽

Debris Cover

AbstractWe present the first direct comparison of turbulence conditions measured simultaneously over exposed ice and a 0.08 m thick supraglacial debris cover on Suldenferner, a small glacier in the Italian Alps. Surface roughness, sensible heat fluxes (~20–50 W m−2), latent heat fluxes (~2–10 W m−2), topology and scale of turbulence are similar over both glacier surface types during katabatic and synoptically disturbed conditions. Exceptions are sunny days when buoyant convection becomes significant over debris-covered ice (sensible heat flux ~ −100 W m−2; latent heat flux ~ −30 W m−2) and prevailing katabatic conditions are rapidly broken down even over this thin debris cover. The similarity in turbulent properties implies that both surface types can be treated the same in terms of boundary layer similarity theory. The differences in turbulence between the two surface types on this glacier are dominated by the radiative and thermal contrasts, thus during sunny days debris cover alters both the local surface turbulent energy fluxes and the glacier component of valley circulation. These variations under different flow conditions should be accounted for when distributing temperature fields for modeling applications over partially debris-covered glaciers.

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Diurnal Energy Balance in a Mango Orchard in the Northeast of Pará, Brazil

Revista Brasileira de Meteorologia ◽

10.1590/0102-7786333012 ◽

2018 ◽

Vol 33 (3) ◽

pp. 537-546 ◽

Cited By ~ 1

Author(s):

Paulo Jorge de Oliveira Ponte de Souza ◽

Juliana Chagas Rodrigues ◽

Adriano Marlisom Leão de Sousa ◽

Everaldo Barreiros de Souza

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Latent Heat ◽

Latent Heat Flux ◽

Soil Cover ◽

Sensible Heat Flux ◽

Sensible Heat ◽

Net Radiation ◽

Growing Seasons ◽

Available Energy

Abstract This study aimed to evaluate the diurnal energy balance during the reproductive stage of two growing seasons of a mango orchard in the northeast of Pará, Brazil. Therefore, a micrometeorological tower was installed and instrumented, in the center of the experimental area, to monitor meteorological variables, besides the phenological evaluation of the mango orchard, which was carried out during growing seasons of 2010-2011 (October 2010 to January 2011) and of 2011-2012 (September 2011 to January 2012). The energy balance was obtained by the bowen ration technique, and the available energy partitioned into heat flux to the ground, sensible heat and latent heat. The amount of rainfall was crucial to the partition of the net radiation in the energy balance components. It provided the variation in the consumption of available energy between 69% and 78% as latent heat flux, and between 23% and 32% as sensible heat flux. The heat flux to the ground was small, representing less than 1% of the net radiation, showing that the mango orchard exhibits good soil cover preventing large variations in soil heating.

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Observed Impact of Atmospheric Aerosols on the Surface Energy Budget

Earth Interactions ◽

10.1175/2013ei000523.1 ◽

2013 ◽

Vol 17 (14) ◽

pp. 1-22 ◽

Cited By ~ 27

Author(s):

Allison L. Steiner ◽

Dori Mermelstein ◽

Susan J. Cheng ◽

Tracy E. Twine ◽

Andrew Oliphant

Keyword(s):

Heat Flux ◽

Surface Energy ◽

Latent Heat ◽

Atmospheric Aerosols ◽

Sensible Heat Flux ◽

Surface Fluxes ◽

Heat Fluxes ◽

Surface Energy Budget ◽

Environmental Drivers ◽

Sensible Heat

Abstract Atmospheric aerosols scatter and potentially absorb incoming solar radiation, thereby reducing the total amount of radiation reaching the surface and increasing the fraction that is diffuse. The partitioning of incoming energy at the surface into sensible heat flux and latent heat flux is postulated to change with increasing aerosol concentrations, as an increase in diffuse light can reach greater portions of vegetated canopies. This can increase photosynthesis and transpiration rates in the lower canopy and potentially decrease the ratio of sensible to latent heat for the entire canopy. Here, half-hourly and hourly surface fluxes from six Flux Network (FLUXNET) sites in the coterminous United States are evaluated over the past decade (2000–08) in conjunction with satellite-derived aerosol optical depth (AOD) to determine if atmospheric aerosols systematically influence sensible and latent heat fluxes. Satellite-derived AOD is used to classify days as high or low AOD and establish the relationship between aerosol concentrations and the surface energy fluxes. High AOD reduces midday net radiation by 6%–65% coupled with a 9%–30% decrease in sensible and latent heat fluxes, although not all sites exhibit statistically significant changes. The partitioning between sensible and latent heat varies between ecosystems, with two sites showing a greater decrease in latent heat than sensible heat (Duke Forest and Walker Branch), two sites showing equivalent reductions (Harvard Forest and Bondville), and one site showing a greater decrease in sensible heat than latent heat (Morgan–Monroe). These results suggest that aerosols trigger an ecosystem-dependent response to surface flux partitioning, yet the environmental drivers for this response require further exploration.

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Uncertainty analysis of computational methods for deriving sensible heat flux values from scintillometer measurements

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-2-1383-2009 ◽

2009 ◽

Vol 2 (3) ◽

pp. 1383-1417 ◽

Cited By ~ 1

Author(s):

P. A. Solignac ◽

A. Brut ◽

J.-L. Selves ◽

J.-P. Béteille ◽

J.-P. Gastellu-Etchegorry ◽

...

Keyword(s):

Heat Flux ◽

Classical Method ◽

Sensible Heat Flux ◽

Bowen Ratio ◽

Heat Fluxes ◽

Eddy Correlation ◽

Time Averaging ◽

Sensible Heat ◽

Ratio Measurement ◽

The Impact

Abstract. The use of scintillometers to determine sensible heat fluxes is now common in studies of land-atmosphere interactions. The main interest in these instruments is due to their ability to quantify energy distributions at the landscape scale, as they can calculate sensible heat flux values over long distances, in contrast to Eddy Correlation systems. However, scintillometer data do not provide a direct measure of sensible heat flux, but require additional data, such as the Bowen ratio (β), to provide flux values. The Bowen ratio can either be measured using Eddy Correlation systems or derived from the energy balance closure. In this work, specific requirements for estimating energy fluxes using a scintillometer were analyzed, as well as the accuracy of two flux calculation methods. We first focused on the classical method (used in standard software). We analysed the impact of the Bowen ratio according to both time averaging and ratio values; for instance, an averaged Bowen ratio (β) of less than 1 proved to be a significant source of measurement uncertainty. An alternative method, called the "β-closure method", for which the Bowen ratio measurement is not necessary, was also tested. In this case, it was observed that even for low β values, flux uncertainties were reduced and scintillometer data were well correlated with the Eddy Correlation results.

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Study of energy balance components at different growth stages of green gram grown in new alluvial zone of West Bengal

MAUSAM ◽

10.54302/mausam.v71i2.29 ◽

2021 ◽

Vol 71 (2) ◽

pp. 315-320

Author(s):

MONDAL SOUMEN ◽

BANERJEE SAON ◽

CHAKRABORTY SHAON ◽

SAHA SALIL ◽

MUKHERJEE ASIS

Keyword(s):

Heat Flux ◽

Energy Balance ◽

West Bengal ◽

Sensible Heat Flux ◽

Bowen Ratio ◽

Green Gram ◽

Growth Stages ◽

Sensible Heat ◽

Net Radiation ◽

Ground Heat Flux

An experiment was conducted in the experimental farm of Bidhan Chandra KrishiViswavidyalaya, Nadia, West Bengal to study the radiation pattern and its balance over green gram (Vignaradiata var. Samrat). The BREB method was used to determine the sensible heat flux and latent energy. The net radiation was measured through net radiometer and the ground heat flux was measured using Fourier's law. Both the diurnal and seasonal variation of net radiation were studied. Similarly, the energy balance components were studied regularly for different crop growth stages as well as on diurnal basis. It is observed that the net radiation varies from 6.32 Wm-2 to 606.43 Wm-2. The latent heat flux constitutes more than 50% of the net radiation for all growth stages as depicted by energy balance partitioning. The sensible heat flux is partitioned into 10% to 20% of total net radiation throughout the growth stages of green gram, which is the lowest in magnitude among all three energy fluxes. The relationship between Bowen ratio and Vapour pressure deficit (VPD), Bowen ratio and Canopy air temperature difference (CATD) was studied. It was found that Bowen ratio is negatively correlated with VPD but positively correlated with CATD. This study enables to monitor ET pattern through latent heat flux and microclimatic characteristics through sensible and ground heat flux.

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Fetch Effect on Flux-Variance Estimations of Sensible and Latent Heat Fluxes of Camellia Sinensis

Atmosphere ◽

10.3390/atmos10060299 ◽

2019 ◽

Vol 10 (6) ◽

pp. 299

Author(s):

Noman Ali Buttar ◽

Hu Yongguang ◽

Josef Tanny ◽

M Waqar Akram ◽

Abdul Shabbir

Keyword(s):

Heat Flux ◽

Eddy Covariance ◽

Latent Heat ◽

Sensible Heat Flux ◽

Soil Heat Flux ◽

Surface Fluxes ◽

Heat Fluxes ◽

Effect Of Temperature ◽

Sensible Heat ◽

Fine Wire

Precise estimation of surface-atmosphere exchange is a major challenge in micrometeorology. Previous literature presented the eddy covariance (EC) as the most reliable method for the measurements of such fluxes. Nevertheless, the EC technique is quite expensive and complex, hence other simpler methods are sought. One of these methods is Flux-Variance (FV). The FV method estimates sensible heat flux (H) using high frequency (~10Hz) air temperature measurements by a fine wire thermocouple. Additional measurements of net radiation (Rn) and soil heat flux (G) allow the derivation of latent heat flux (LE) as the residual of the energy balance equation. In this study, the Flux Variance method was investigated, and the results were compared against eddy covariance measurements. The specific goal of the present study was to assess the performance of the FV method for the estimation of surface fluxes along a variable fetch. Experiment was carried out in a tea garden; an EC system measured latent and sensible heat fluxes and five fine-wire thermocouples were installed towards the wind dominant direction at different distances (fetch) of TC1 = 170 m, TC2 = 165 m, TC3 = 160 m, TC4 = 155 m and TC5 = 150 m from the field edge. Footprint analysis was employed to examine the effect of temperature measurement position on the ratio between 90% footprint and measurement height. Results showed a good agreement between FV and EC measurements of sensible heat flux, with all regression coefficients (R2) larger than 0.6; the sensor at 170 m (TC1), nearest to the EC system, had highest R2 = 0.86 and lowest root mean square error (RMSE = 25 Wm−2). The estimation of LE at TC1 was also in best agreement with eddy covariance, with the highest R2 = 0.90. The FV similarity constant varied along the fetch within the range 2.2–2.4.

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