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

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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Energy balance and evapotranspiration estimates for a mature coniferous forest

Canadian Journal of Forest Research ◽

10.1139/x78-067 ◽

1978 ◽

Vol 8 (4) ◽

pp. 456-462 ◽

Cited By ~ 12

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.

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

Hydrology and Earth System Sciences ◽

10.5194/hess-21-3401-2017 ◽

2017 ◽

Vol 21 (7) ◽

pp. 3401-3415 ◽

Cited By ~ 18

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.

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

10.5194/egusphere-egu21-6903 ◽

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

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.&#160;

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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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Evaluation of Two Land Surface Schemes Used in Terrains of Increasing Aridity in West Africa

Journal of Hydrometeorology ◽

10.1175/2007jhm797.1 ◽

2008 ◽

Vol 9 (2) ◽

pp. 173-193 ◽

Cited By ~ 11

Author(s):

D. Schüttemeyer ◽

A. F. Moene ◽

A. A. M. Holtslag ◽

H. A. R. de Bruin

Keyword(s):

Heat Flux ◽

West Africa ◽

Latent Heat ◽

Latent Heat Flux ◽

Land Surface ◽

Sensible Heat Flux ◽

Surface Fluxes ◽

Semiarid Region ◽

Canopy Conductance ◽

Net Radiation

Abstract In this study different parameterizations for land surface models currently employed in meteorological models at ECMWF [Tiled ECMWF Surface Scheme for Exchange Processes over Land (TESSEL)] and NCEP (Noah) are evaluated for a semiarid region in Ghana, West Africa. Both schemes utilize the Jarvis–Stewart approach to calculate canopy conductance as the critical variable for partitioning the available energy into sensible and latent heat flux. Additionally, an approach within Noah is tested to calculate canopy conductance based on plant physiology (A-gs method), where the photosynthetic assimilation is coupled to the leaf stomatal conductance. All parameterizations were run offline for a seasonal cycle in 2002/03 using observations as forcings at two test sites. The two locations are in the humid tropical southern region and in the drier northern region. For the purpose of forcing and evaluation, a new set of data has been utilized to include surface fluxes obtained by scintillometry. The measurements include the rapid wet-to-dry transition after the wet season at both sites. As a general trend, it has been found that during the wet period of a season net radiation is described well by all parameterizations. During the drying process the errors in modeled net radiation increased at both sites. The models perform poorly in simulating soil heat fluxes with larger errors for TESSEL for both sites. The evolution in time for sensible heat flux and latent heat flux was tackled in different ways by the utilized parameterizations and sites with enhanced model performance for the more southern site. Soil moisture in the upper soil layers is modeled with small errors for the different parameterizations. Key adjustments for reducing net radiation during the dry period of a season are discussed. In particular, the ratio of roughness length of momentum and heat was found to be an important parameter, but will require seasonal adjustments.

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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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Thermal Modification of Air Moving Over Melting Snow Surfaces

Annals of Glaciology ◽

10.3189/1985aog6-1-235-237 ◽

1985 ◽

Vol 6 ◽

pp. 235-237 ◽

Cited By ~ 2

Author(s):

Hiroshi Takahara ◽

Keiji Hlguchi

Keyword(s):

Heat Flux ◽

Air Temperature ◽

Sensible Heat Flux ◽

Thermal Modification ◽

Snow Surface ◽

Net Radiation ◽

Downwind Distance ◽

Melting Snow ◽

Covered Area ◽

Neutral Stratification

Observations were made on thermal modification due to cooling when air flows from a grass-covered area onto a melting snow surface. To clarify the relation between such modification of air and snowmelt, the downwind variation of temperature, humidity and wind speed, together with net radiation and spatial variation of snowmelt were observed at a small snow patch measuring 70 m long and 30 m wide. When air temperature was between 10 and 20°C, with nearly neutral stratification over the upwind grass-covered area, air temperature at 0.1 m level decreased by 4 to 9°C over the downwind distance of 48 m above the snow patch, and so the sensible heat flux decreased in the downwind direction. As a result of such cooling, snowmelt in the central part of the snow patch was found to be about 25% smaller than near its edge. This value can be explained by the decrease of the total heat flux toward the snow surface due to the air modification.

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Radiation and energy balance of lettuce culture inside a polyethylene greenhouse

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x1999001000003 ◽

1999 ◽

Vol 34 (10) ◽

pp. 1775-1786 ◽

Cited By ~ 1

Author(s):

Valéria de Almeida Frisina ◽

João Francisco Escobedo

Keyword(s):

Heat Flux ◽

Energy Balance ◽

Global Radiation ◽

Soil Surface ◽

Soil Heat Flux ◽

Short Wave ◽

Wave Radiation ◽

Radiation Balance ◽

Net Radiation ◽

Crop Cycle

The objective of this paper was to describe the radiation and energy balance, during the lettuce (Lactuca sativa, L. cv. Verônica) crop cycle inside a polyethylene greenhouse. The radiation and energy balance was made inside a tunnel greenhouse with polyethylene cover (100 mum) and in an external area, both areas with 35 m². Global, reflected and net radiation, soil heat flux and air temperature (dry and humid) were measured during the crop cycle. A Datalogger, which operated at 1 Hz frequency, storing 5 minutes averages was utilized. The global (K¯) and reflected (K) radiations showed that the average transmission of global radiation (K¯in / K¯ex) was almost constant, near to 79.59%, while the average ratio of reflected radiation (Kin / Kex) was 69.21% with 8.47% standard-deviation. The normalized curves of short-wave net radiation, in relation to the global radiation (K*/ K¯), found for both environments, were almost constant at the beginning of cycle; this relation decreased in the final stage of culture. The normalized relation (Rn/ K¯) was bigger in the external area, about 12%, when the green culture covered the soil surface. The long-wave radiation balance average (L*) was bigger outside, about 50%. The energy balance, estimated in terms of vertical fluxes, showed that, for the external area, in average, 83.07% of total net radiation was converted in latent heat evaporation (LE), and 18% in soil heat flux (G), and 9.96% in sensible heat (H), while inside of the greenhouse, 58.71% of total net radiation was converted in LE, 42.68% in H, and 28.79% in G.

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Thermal Modification of Air Moving Over Melting Snow Surfaces

Annals of Glaciology ◽

10.1017/s0260305500010442 ◽

1985 ◽

Vol 6 ◽

pp. 235-237 ◽

Cited By ~ 12

Author(s):

Hiroshi Takahara ◽

Keiji Hlguchi

Keyword(s):

Heat Flux ◽

Air Temperature ◽

Sensible Heat Flux ◽

Thermal Modification ◽

Snow Surface ◽

Net Radiation ◽

Downwind Distance ◽

Melting Snow ◽

Covered Area ◽

Neutral Stratification

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Effects of Incorporating Measured Leaf Optical Properties in Land Surface Models

Frontiers in Earth Science ◽

10.3389/feart.2021.663917 ◽

2021 ◽

Vol 9 ◽

Author(s):

Wenzong Dong ◽

Hua Yuan ◽

Ruqing Zhang ◽

Hongmei Li ◽

Lina Huang ◽

...

Keyword(s):

Heat Flux ◽

Land Surface ◽

Sensible Heat Flux ◽

Surface Radiation ◽

Sensible Heat ◽

Net Radiation ◽

Land Surface Models ◽

Forest Zone ◽

Leaf Optical Properties ◽

Surface Models

Leaf optical properties (LOPs, i.e., leaf reflectance and transmittance), as a fundamental property of vegetation, are a key parameter in the canopy radiative transfer process. LOPs have a direct impact on the surface solar radiation partition and further affect surface flux exchanges. Recent works have provided reliable LOP data and mentioned that notable differences exist between the prescribed LOP values in current land surface models and measured LOP values, especially in the near-infrared (NIR) band. To evaluate the effects of different LOP values in land surface modeling, we ran two land surface models (the Community Land Model and the Common Land Model) with their default prescribed and measured values to examine the differences in simulated surface radiation partitions and fluxes. Our analyses show that differences in LOP values can lead to a large discrepancy in albedo, radiation partition, sensible heat flux and net radiation simulations. By using the measured LOP values, in the boreal forest zone, Southeast China, and the eastern United States, both models have a significantly increased surface albedo in the NIR band, with the difference exceeding 10% during JJA. Thus, the measured LOP values can improve the negative albedo bias in the boreal forest zone during summertime. Moreover, both models simulate less net radiation with a maximum reduction of 11 W/m2 when incorporating the measured LOP values. Therefore, the total sensible heat flux can be reduced by as much as 11 W/m2. The results of this study emphasize that different LOP values can have a considerable effect on the surface radiation budget and sensible heat flux simulations which need attention in land surface model development. However, in current offline simulations, the measured LOP values cause slight changes in land surface temperatures and gross primary productivity (GPP).

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