Energy balance and evapotranspiration estimates for a mature coniferous forest

1978 ◽  
Vol 8 (4) ◽  
pp. 456-462 ◽  
Author(s):  
J. H. McCaughey
Keyword(s):  
Heat Flux ◽  
Soil Moisture ◽  
Energy Balance ◽  
Potential Evapotranspiration ◽  
Coniferous Forest ◽  
Sensible Heat Flux ◽  
Net Radiation ◽  
Balance Study ◽  
Strongly Coupled ◽  
Volumetric Soil Moisture

Results of an energy balance study conducted in 1974 at Montmorency, Quebec, are reported. The energy balance components of a balsam fir (Abiesbalsamea L. Mill.) canopy, evaluated for 7 sample days, show marked differences in energy partitioning. The days are separated into two groups. The difference in the energy balance between the groups is related to the value of volumetric soil moisture in the top 0.1 m of soil. On days when the volumetric soil moisture is 36% or more, potential evapotranspiration conditions are operative, and evapotranspiration is the largest term in the energy balance. Also, it is strongly coupled to net radiation. Whenever the volumetric soil moisture is 32% or less, potential evapotranspiration conditions are not operative, and characteristically, the sensible heat flux to the air is the same or slightly larger than the evapotranspiration. Both fluxes are strongly coupled to the net radiation. For all hours the soil heat flux is negligible. For potential evapotranspiration, the equation developed by Priestley and Taylor is tested. Under potential evapotranspiration conditions the equation, with α = 1.26, estimates daily water loss to within 3%. The Bowen ratio solution to the energy balance is used as the standard for comparison. Whenever the volumetric soil moisture is 32% or less, α is variable and less than 1.26. The minimum value found is 0.67.

scholarly journals Analysing surface energy balance closure and partitioning over a semi-arid savanna FLUXNET site in Skukuza, Kruger National Park, South Africa

2017 ◽  
Vol 21 (7) ◽  
pp. 3401-3415 ◽  
Author(s):  
Nobuhle P. Majozi ◽  
Chris M. Mannaerts ◽  
Abel Ramoelo ◽  
Renaud Mathieu ◽  
Alecia Nickless ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Latent Heat ◽  
Surface Energy Balance ◽  
Sensible Heat Flux ◽  
Dry Season ◽  
Energy Balance Closure ◽  
Net Radiation ◽  
Wet Season

Abstract. Flux towers provide essential terrestrial climate, water, and radiation budget information needed for environmental monitoring and evaluation of climate change impacts on ecosystems and society in general. They are also intended for calibration and validation of satellite-based Earth observation and monitoring efforts, such as assessment of evapotranspiration from land and vegetation surfaces using surface energy balance approaches. In this paper, 15 years of Skukuza eddy covariance data, i.e. from 2000 to 2014, were analysed for surface energy balance closure (EBC) and partitioning. The surface energy balance closure was evaluated using the ordinary least squares regression (OLS) of turbulent energy fluxes (sensible (H) and latent heat (LE)) against available energy (net radiation (Rn) less soil heat (G)), and the energy balance ratio (EBR). Partitioning of the surface energy during the wet and dry seasons was also investigated, as well as how it is affected by atmospheric vapour pressure deficit (VPD), and net radiation. After filtering years with low-quality data (2004–2008), our results show an overall mean EBR of 0.93. Seasonal variations of EBR also showed the wet season with 1.17 and spring (1.02) being closest to unity, with the dry season (0.70) having the highest imbalance. Nocturnal surface energy closure was very low at 0.26, and this was linked to low friction velocity during night-time, with results showing an increase in closure with increase in friction velocity. The energy partition analysis showed that sensible heat flux is the dominant portion of net radiation, especially between March and October, followed by latent heat flux, and lastly the soil heat flux, and during the wet season where latent heat flux dominated sensible heat flux. An increase in net radiation was characterized by an increase in both LE and H, with LE showing a higher rate of increase than H in the wet season, and the reverse happening during the dry season. An increase in VPD is correlated with a decrease in LE and increase in H during the wet season, and an increase in both fluxes during the dry season.

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

2018 ◽  
Vol 33 (3) ◽  
pp. 537-546 ◽  
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.

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

MAUSAM ◽  
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.

scholarly journals Analysing surface energy balance closure and partitioning over a semi-arid savanna FLUXNET site in Skukuza, Kruger National Park, South Africa

2017 ◽  
Author(s):  
Nobuhle P. Majozi ◽  
Chris M. Mannaerts ◽  
Abel Ramoelo ◽  
Renaud Mathieu ◽  
Alecia Nickless ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Latent Heat ◽  
Friction Velocity ◽  
Surface Energy Balance ◽  
Sensible Heat Flux ◽  
Energy Balance Closure ◽  
Net Radiation ◽  
Wet Season

Abstract. Flux towers provide essential terrestrial climate, water and radiation budget information needed for environmental monitoring and evaluation of climate change impacts on ecosystems and society in general. They are also intended for calibration and validation of satellite-based earth observation and monitoring efforts, such as assessment of evapotranspiration from land and vegetation surfaces using surface energy balance approaches. In this paper, 15 years of Skukuza eddy covariance data, i.e. from 2000 to 2014, were analysed for surface energy balance closure (EBC) and partitioning. The surface energy balance closure was evaluated using the ordinary least squares regression (OLS) of turbulent energy fluxes (sensible (H) and latent heat (LE)) against available energy (net radiation (Rn) less soil heat (G)), and the energy balance ratio (EBR). Partitioning of the surface energy during the wet and dry seasons was investigated, as well as how it is affected by atmospheric vapor pressure deficit (VPD), and net radiation. After filtering years with bad data (2004–2008), our results show an overall mean EBR of 0.93. Seasonal variations of EBR also showed summer (0.98) and spring (1.02) were closest to unity, with winter (0.70) having the least closure. Nocturnal surface energy closure was very low at 0.11, and this was linked to low friction velocity during night-time, with results showing an increase in closure with increase in friction velocity. The surface energy partitioning of this savanna ecosystem showed that sensible heat flux dominated the energy partitioning between March and October, followed by latent heat flux, and lastly the soil heat flux, and during the wet season where latent heat flux dominated the sensible heat flux. An increase in net radiation was characterized by an increase in both LE and H, with LE showing a higher rate of increase than H in the wet season, and the reverse happening during the dry season. An increase in VPD is characterized by a decrease in LE and increase in H during the wet season, and an increase of both fluxes during the dry season.

scholarly journals Comparison of energy balance on Gangotri and Chhota Shigri Glaciers

2014 ◽  
Vol XL-8 ◽  
pp. 537-542
Author(s):  
G. Rastogi ◽  
Ajai
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Net Radiation ◽  
Chhota Shigri Glacier ◽  
Himalayan Glaciers ◽  
Gangotri Glacier

Surface energy balance of a glacier governs the physical processes taking place at the surface-atmosphere interface and connects ice ablation/accumulation to climate variability. To understand the response of Himalayan glaciers to climatic variability, a study was taken to formulate energy balance equation on two of the Indian Himalayan glaciers, one each from Indus and Ganga basins, which have different climatic and physiographic conditions. Study was carried out over Gangotri glacier (Ganga basin) and Chhota Shigri(CS) glacier from Chandra sub-basin (Indus basin). Gangotri glacier is one of the largest glaciers in the central Himalaya located in Uttarkashi District, Uttarakhand, India. Chhota Shigri glacier of Chandra sub-basin lies in Lahaul and Spiti valley of Himachal Pradesh. Energy balance components have been computed using inputs derived from satellite data, AWS (Automatic Weather Station) data and field measurements. Different components of energy balance computed are net radiation (includes net shortwave and net longwave radiation), sensible heat flux and latent heat flux. In this study comparison has been made for each of the above energy balance components as well as total energy for the above glaciers for the months of November and December, 2011. It is observed that net radiation in Gangotri glacier is higher by approximately 43 % in comparison to Chhota Shigri glacier; Sensible heat flux is lesser by 77 %; Latent heat flux is higher by 66 % in the month of November 2011. Comparison in the month of December shows that net radiation in Gangotri glacier is higher by approximately 22 % from Chhota Shigri glacier; Sensible heat flux is lesser by 90 %; Latent heat flux is higher by 3 %.Total energy received at the glacier surface and contributes for melting is estimated to be around 32 % higher in Gangotri than Chhota Shigri glacier in November, 2011 and 1.25 % higher in December, 2011. The overall results contribute towards higher melting rate in November and December, 2011 in Gangotri than Chhota Shigri glacier.

scholarly journals Estimating Soil Moisture in Small Watersheds, Using a Water Balance Approach

2002 ◽  
Vol 33 (5) ◽  
pp. 373-390 ◽  
Author(s):  
Chang-Soo Rim ◽  
L.W. Gay
Keyword(s):  
Heat Flux ◽  
Soil Moisture ◽  
Energy Balance ◽  
Water Balance ◽  
Sensible Heat Flux ◽  
Soil Heat Flux ◽  
Time Domain Reflectometry ◽  
Precipitation Pattern ◽  
Simple Correlation ◽  
Small Watersheds

Soil moisture content was estimated daily by a energy balance and water budget (EBWB) analysis of two small subwatersheds in the Walnut Gulch Experimental Watershed near Tombstone, Arizona. One watershed was 8.1 ha and covered with grass, and the other was 48.6 ha and covered with shrubs. The four-week experiment took place in July and August, during the summer rainy season that dominates the precipitation pattern of southern Arizona. Mean daily soil moisture (SM, mm) was estimated by a water balance at each watershed, using precipitation (P), runoff (RO) and evapotranspiration (ET). Daily ET estimates were derived from an energy balance on each watershed, using measured net radiation (Qn), soil heat flux (Qg) and sensible heat flux (Qh) to solve for latent energy (QLE, and hence ET) as a residual term. Next, independent estimates of watershed SM were obtained from Time Domain Reflectometry (TDR). The results of simple correlation analyses between the methods showed that the simple correlation coefficients for Lucky Hills and Kendall are 0.764 and 0.791 respectively. The agreement of the two sets of soil moisture measurements confirms that simple water and energy balance measurements can yield appropriate estimates of soil moisture in small watersheds.

scholarly journals Solar and net radiation, available energy and its influence on evapotranspiration from grass.

1961 ◽  
Vol 9 (2) ◽  
pp. 81-93
Author(s):  
D.W. Scholte Ubing
Keyword(s):  
Soil Moisture ◽  
Energy Balance ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Global Radiation ◽  
Water Vapour Pressure ◽  
Net Radiation ◽  
Atmospheric Conditions ◽  
Weather Factors ◽  
Available Energy

From studies on radiation and energy balance in the Netherlands it is concluded that reliable values for net radiation over 24-hr periods can be obtained by computation, if differences in the weather during day and night are taken into account. A comparison is given of measured net radiation above short grass with net radiation computed from air temperature, water vapour pressure in the air and sunshine duration. Variations in the nature of a cropped surface, as a consequence of variations in conditions of such a surface, may influence the radiation and energy balance. However, if soil moisture becomes less available for plant roots, soil moisture content has a much more important influence on the proportion of the available energy used in heating the soil, the air and in evapotranspiration than the type and nature of the soil cover. For daily and 24-hr periods with similar atmospheric conditions, a linear relationship between total global radiation and net radiation can be expected. The ratio between evapotranspiration from short grass under optimal water supply and the evaporation from a wet surface (or thin water layer) varied greatly for short periods of time under different conditions of radiation and temperature. These variations could be due to plant or weather factors influencing the stomatal apertures, although variations in stability of the lower air layers may have had some influence. Variations in intensity of potential and of maximum evapotranspiration rates and differences in the diurnal variations, as compared with the diurnal variation of net radiation, are shown. A decrease of actual evapotranspiration from crops as soil moisture becomes less available and, of course, the potential evapotranspiration rate, strongly depend on the net radiation gain. F. s.- R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Energy balance at the land-surface interface

MAUSAM ◽  
2021 ◽  
Vol 47 (2) ◽  
pp. 115-124
Author(s):  
SANGEETA SAXENA ◽  
J. S. PILLAI ◽  
B. S. MURTHY ◽  
K. G. VERNEKAR
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Energy Budget ◽  
Land Surface ◽  
Sensible Heat Flux ◽  
Bare Soil ◽  
Soil Heat Flux ◽  
Tropical Meteorology ◽  
Small Scale ◽  
Net Radiation

A small scale field experiment was conducted at the Indian Institute of Tropical Meteorology (IITM). Pashan Pune and the energy budget at the land surface interface was studied for clear and cloudy days over bare soil. Using instrumented towers, a net radiometer and soil temperature probe all the components of the energy budget. i.e. the sensible heat flux, latent heat flux, soil heat flux and net radiation were measured directly and the energy balance was computed. It is observed that when considered over the whole day, the energy budget is fairly balanced. As a part of energy budget, the Bowen's ratio is also discussed.

scholarly journals Validation of the Deardorff model for estimating energy balance components for a sugarcane crop

2008 ◽  
Vol 65 (4) ◽  
pp. 325-334 ◽  
Author(s):  
Glauco de Souza Rolim ◽  
João Francisco Escobedo ◽  
Amauri Pereira Oliveira
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Latent Heat ◽  
Sensible Heat Flux ◽  
Reference Level ◽  
Sensible Heat ◽  
Net Radiation ◽  
Area Index ◽  
Sugarcane Crop ◽  
Aerodynamic Method

The quantification of the available energy in the environment is important because it determines photosynthesis, evapotranspiration and, therefore, the final yield of crops. Instruments for measuring the energy balance are costly and indirect estimation alternatives are desirable. This study assessed the Deardorff's model performance during a cycle of a sugarcane crop in Piracicaba, State of São Paulo, Brazil, in comparison to the aerodynamic method. This mechanistic model simulates the energy fluxes (sensible, latent heat and net radiation) at three levels (atmosphere, canopy and soil) using only air temperature, relative humidity and wind speed measured at a reference level above the canopy, crop leaf area index, and some pre-calibrated parameters (canopy albedo, soil emissivity, atmospheric transmissivity and hydrological characteristics of the soil). The analysis was made for different time scales, insolation conditions and seasons (spring, summer and autumn). Analyzing all data of 15 minute intervals, the model presented good performance for net radiation simulation in different insolations and seasons. The latent heat flux in the atmosphere and the sensible heat flux in the atmosphere did not present differences in comparison to data from the aerodynamic method during the autumn. The sensible heat flux in the soil was poorly simulated by the model due to the poor performance of the soil water balance method. The Deardorff's model improved in general the flux simulations in comparison to the aerodynamic method when more insolation was available in the environment.

scholarly journals (356) Adaptation of Makkink Model to Obtain Potential Evapotranspiration under Sonoran Desert Conditions

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1018A-1018
Author(s):  
Fabián Robles-Contreras ◽  
Raul Leonel Grijalva-Contreras ◽  
Manuel de Jesus Valenzuela-Ruiz ◽  
Rubén Macias-Duarte
Keyword(s):  
Heat Flux ◽  
Sonoran Desert ◽  
Potential Evapotranspiration ◽  
Global Radiation ◽  
Sensible Heat Flux ◽  
Weather Station ◽  
Net Radiation ◽  
Fixed Rate ◽  
A Value ◽  
Northwestern Mexico

Water is a very limited resource in the Sonoran Desert region of Caborca, Sonora, Mexico. For an efficient use of irrigation water, a method of calculating water requirements of the crops is needed. Potential evapotranspiration (Eto) value obtained with the Penman-Monteith model from a regional weather station was not dependable, since some parameters, such as sensible heat flux in the soil, are estimated from a fixed rate with net radiation (Rn), also an estimated value. The weather station did not have a sensor for heat flux in its network. Studies in northwestern Mexico have indicated that it is feasible to adapt the use of the Makkink model, because a single measurement of solar radiation and temperature would be required. We compared the daily Makkink Eto against the Class A pan method (control) Eto during 75 days and found a value of 0.81 mm/day less with the Makkink model. To fit the Makkink model to regional conditions, we ran the Makkink model varying the value of C constant (from 0.5 to 0.95), and found that a value of C = 0.87 substituted for C = 0.65 (original value) has an daily average difference of 0.09 mm/day less with respect to the control. This could be because there are few clouds in the region, and a greater proportion of global radiation arrives at the surface from the earth or the crops in form of net radiation.

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