Net radiation, sensible and latent heat flux densities on slopes computed by the energy balance method

1990 ◽  
Vol 53 (1-2) ◽  
pp. 163-171 ◽  
Author(s):  
Leo Fritschen ◽  
Ping Qian
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Balance Method ◽  
Net Radiation ◽  
Energy Balance Method

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 The surface energy balance of a polygonal tundra site in northern Siberia – Part 1: Spring to fall

2011 ◽  
Vol 5 (1) ◽  
pp. 151-171 ◽  
Author(s):  
M. Langer ◽  
S. Westermann ◽  
S. Muster ◽  
K. Piel ◽  
J. Boike
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Snow Cover ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Surface Energy Balance ◽  
Heat Fluxes ◽  
Net Radiation ◽  
Ground Heat Flux

Abstract. In this article, we present a study on the surface energy balance of a polygonal tundra landscape in northeast Siberia. The study was performed during half-year periods from April to September in each of 2007 and 2008. The surface energy balance is obtained from independent measurements of the net radiation, the turbulent heat fluxes, and the ground heat flux at several sites. Short-wave radiation is the dominant factor controlling the magnitude of all the other components of the surface energy balance during the entire observation period. About 50% of the available net radiation is consumed by the latent heat flux, while the sensible and the ground heat flux are each around 20 to 30%. The ground heat flux is mainly consumed by active layer thawing. About 60% of the energy storage in the ground is attributed to the phase change of soil water. The remainder is used for soil warming down to a depth of 15 m. In particular, the controlling factors for the surface energy partitioning are snow cover, cloud cover, and the temperature gradient in the soil. The thin snow cover melts within a few days, during which the equivalent of about 20% of the snow-water evaporates or sublimates. Surface temperature differences of the heterogeneous landscape indicate spatial variabilities of sensible and latent heat fluxes, which are verified by measurements. However, spatial differences in the partitioning between sensible and latent heat flux are only measured during conditions of high radiative forcing, which only occur occasionally.

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 Large Aperture Scintillometer measurements above a large green roof to assess the evapotranspiration flux

2020 ◽  
Author(s):  
Leydy Alejandra Castellanos Diaz ◽  
Pierre Antoine Versini ◽  
Ioulia Tchiguirinskaia ◽  
Olivier Bonin ◽  
David Ramier
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Energy Balance ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Green Roof ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Net Radiation ◽  
Large Aperture

<p>The challenges induced by the continuous urbanization and the climate change effects, such as extreme events (e.g. flooding or heat waves) or the intense increase of the urban temperatures (Urban Heat Island), encourage the implementation of Blue and Green Solutions (BGS). These solutions are inspired by the nature, favouring natural process in the cities like water infiltration or evapotranspiration (ET), reducing air temperature during heatwaves events.</p><p>Characterize the thermal behavior governing a BGS is necessary to promote their implementation. Consequently, this research studies the energy fluxes –and particularly the evapotranspiration one- of a 1 ha wavy-shape green roof located in Champs-Sur-Marne (France), called Blue Green Wave (BGW). Therefore, a Large Aperture Scintillometer MKI, a CNR4 radiometer and 4 Type K thermocouples were installed on the BGW to measure the sensible heat flux of convection, the net radiation and the heat conduction into the soil substrate. The latent heat flux of ET was deduced from the energy balance.</p><p>Each LAS unit was placed on the highest locations of the roof with about 100 m of distance between them. Diaphragms for short-range applications were placed in front of the units. The measurements were conducted on sunny and randomly days during the 2019 summer over an average time period of 7 hours.</p><p>It appears that LAS sensible heat flux measurements on completely sunny days follow the net radiation flux trend. However, on cloudy days important flux fluctuations are noticed. Therefore, a sensitivity analysis was carried out to illustrate the significant correlation between the wind and the sensible heat flux during short time periods. In parallel, the heat conduction was analysed through a thermal gradient of temperature and a Fourier analysis demonstrating a poor conduction rate mainly on drier conditions of the BGW.</p><p>Finally, the deduced latent heat was compared with the measurements of a dynamic evaporation chamber, confirming a significant over estimation of the latent heat computed from the energy balance. This can be explained by the sum of uncertainties related to each energy flux component, in addition to the restraint conditions of LAS measurement operation on the BGW (application over the limits of MOST theory). A multifractal analysis to determinate the temporal and spatial scaling behaviour of latent heat flux is ongoing.</p>

scholarly journals The surface energy balance of a polygonal tundra site in northern Siberia – Part 2: Winter

2011 ◽  
Vol 5 (2) ◽  
pp. 509-524 ◽  
Author(s):  
M. Langer ◽  
S. Westermann ◽  
S. Muster ◽  
K. Piel ◽  
J. Boike
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Surface Energy ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Surface Energy Balance ◽  
Sensible Heat ◽  
Net Radiation ◽  
Northern Siberia ◽  
Ground Heat Flux

Abstract. In this study, we present the winter time surface energy balance at a polygonal tundra site in northern Siberia based on independent measurements of the net radiation, the sensible heat flux and the ground heat flux from two winter seasons. The latent heat flux is inferred from measurements of the atmospheric turbulence characteristics and a model approach. The long-wave radiation is found to be the dominant factor in the surface energy balance. The radiative losses are balanced to about 60 % by the ground heat flux and almost 40 % by the sensible heat fluxes, whereas the contribution of the latent heat flux is small. The main controlling factors of the surface energy budget are the snow cover, the cloudiness and the soil temperature gradient. Large spatial differences in the surface energy balance are observed between tundra soils and a small pond. The ground heat flux released at a freezing pond is by a factor of two higher compared to the freezing soil, whereas large differences in net radiation between the pond and soil are only observed at the end of the winter period. Differences in the surface energy balance between the two winter seasons are found to be related to differences in snow depth and cloud cover which strongly affect the temperature evolution and the freeze-up at the investigated pond.

scholarly journals Micrometeorological methods to estimate sugarcane evapotranspiration in coastal northeastern region of Brazil

2019 ◽  
pp. 1422-1428
Author(s):  
Adolpho Emanuel Quintela da Rocha ◽  
José Leonaldo de Souza ◽  
Guilherme Bastos Lyra ◽  
Ricardo Araújo Ferreira Junior ◽  
Gustavo Bastos Lyra ◽  
...  
Keyword(s):  
Heat Flux ◽  
Energy Balance ◽  
Eddy Covariance ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Bowen Ratio ◽  
Water Vapour Pressure ◽  
Sensible Heat ◽  
Energy Balance Method ◽  
Ratio Energy

The aim of the present work was to evaluate the performance of Bowen ratio-energy balance method, as well as the energy balance closure by Eddy covariance technique for a sugarcane crop in Brazilian northeastern region. Micrometeorological measurements were carried out between June 7th and November 17th, 2013. Latent and sensible heat fluxes were determined through Eddy covariance technique (EC) and by the Bowen ratio-energy balance method (BREB), considering two approaches. The first, estimated the air temperature and water vapour pressure gradient in two levels above the canopy. The second method measured the air temperature and water vapour pressure at the first level and the surface temperature from radiometric measurements. Latent heat flux was also estimated as energy balance residue from determinations of the sensible heat flux by Eddy covariance. The degree of energy balance closure was dependent on the time of the day considered. Bowen ratio - energy balance estimated from the first approach, showed the best agreement with the eddy covariance measurements to estimate latent heat flux, while in the second case, when the Bowen ratio was estimated using the surface temperature, the linear relationship was the most discrepant. Therefore, the Bowen ratio conventional method is more suitable for estimating latent heat flux in sugarcane.

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.

Characteristics of Long-term Surface Heat Source and Its Climate Influence Factors in Central Tibetan Plateau

2021 ◽  
Author(s):  
Zeyong Hu ◽  
Xiaoqiang Yan
Keyword(s):  
Heat Flux ◽  
Heat Source ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Sensible Heat Flux ◽  
Surface Heat ◽  
Sensible Heat ◽  
Net Radiation ◽  
Maximum Value

<p>Based on multi-level AWS data during 2001 to 2015 and eddy covariance data during 2011 to 2014 at Nagqu Station of Plateau Climate and Environment, the turbulent fluxes were calculated by a surface energy balance combination (CM) and eddy covariance ( EC) method. A long-term heat fluxes and surface heat source were obtained with comparison and correction of EC and CM fluxes. The surface energy closure ratio is close to 1 in spring, summer and autumn. But it reaches to 1.34 in winter due to low net radiation observation value on snow surface. The sensible heat flux shows a ascend trend while latent heat flux shows a descend trend during 2002 to 2015. The surface heat source shows a descend trend. The analysis of the surface heat source indicates that it has a significant relationship with net radiation flux, surface temperature, soil moisture and wind speed. Particularly, the surface heat source has a significant response to net radiation flux throughout the year. There are obvious influences of surface temperature and soil moisture on the surface heat source in spring, autumn and winter. And the influence of wind speeds on surface heat source is strong only in spring. The annual variation of sensible heat flux and latent heat flux are obvious. Sensible heat flux reaches the maximum value of the year in April and the minimum value in July. however, latent heat flux shows the maximum value in July and the minimum value in January. </p>

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