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)

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 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 Radiation and energy balance of lettuce culture inside a polyethylene greenhouse

1999 ◽  
Vol 34 (10) ◽  
pp. 1775-1786 ◽  
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<FONT FACE=Symbol>¯</FONT>) and reflected (K<FONT FACE=Symbol></FONT>) radiations showed that the average transmission of global radiation (K<FONT FACE=Symbol>¯</FONT>in / K<FONT FACE=Symbol>¯</FONT>ex) was almost constant, near to 79.59%, while the average ratio of reflected radiation (K<FONT FACE=Symbol></FONT>in / K<FONT FACE=Symbol></FONT>ex) was 69.21% with 8.47% standard-deviation. The normalized curves of short-wave net radiation, in relation to the global radiation (K*/ K<FONT FACE=Symbol>¯</FONT>), 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<FONT FACE=Symbol>¯</FONT>) 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.

scholarly journals Components of near-surface energy balance derived from satellite soundings – Part 1: Net available energy

2014 ◽  
Vol 11 (8) ◽  
pp. 11825-11861 ◽  
Author(s):  
K. Mallick ◽  
A. Jarvis ◽  
G. Wohlfahrt ◽  
G. Kiely ◽  
T. Hirano ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Surface Radiation ◽  
Net Radiation ◽  
Heat Accumulation ◽  
Simple Method ◽  
Ground Truth Data ◽  
Near Surface ◽  
Available Energy

Abstract. This paper introduces a relatively simple method for recovering global fields of near-surface net available energy (the sum of the sensible and latent heat flux or the difference between the net radiation and surface heat accumulation) using satellite visible and infra-red products derived from the AIRS (Atmospheric Infrared Sounder) and MODIS (MOderate Resolution Imaging Spectroradiometer) platforms. The method focuses on first specifying net surface radiation by considering its various shortwave and longwave components. This was then used in a surface energy balance equation in conjunction with satellite day–night surface temperature difference to derive 12 h discrete time estimates of surface, system heat capacity and heat accumulation, leading directly to retrieval for surface net available energy. Both net radiation and net available energy estimates were evaluated against ground truth data taken from 30 terrestrial tower sites affiliated to the FLUXNET network covering 7 different biome classes. This revealed a relatively good agreement between the satellite and tower data, with a pooled root mean square deviation of 98 and 72 W m−2 for net radiation and net available energy, respectively, although both quantities were underestimated by approximately 25 and 10%, respectively relative to the tower observations. Analysis of the individual shortwave and longwave components of the net radiation revealed the downwelling shortwave radiation to be the main source of this systematic underestimation.

scholarly journals Why has catchment evaporation increased in the past 40 years? A data-based study in Austria

2018 ◽  
Author(s):  
Doris Duethmann ◽  
Günter Blöschl
Keyword(s):  
Soil Moisture ◽  
Vegetation Index ◽  
Global Radiation ◽  
The Past ◽  
Available Energy ◽  
Vegetation Activity ◽  
Regional Evapotranspiration ◽  
Monteith Equation ◽  
Term Data

Abstract. Global warming has increased regional evapotranspiration in many parts of the world in the last decades, but the drivers of these increases are widely debated. Part of the difficulty lies in the scarcity of high-quality long term data on evapotranspiration. In this paper, we analyze changes in catchment evapotranspiration estimated from the water balances of 156 catchments in Austria over the period 1977–2014 and attribute them to changes in atmospheric demand and available energy, vegetation, and soil moisture as possible drivers. Trend analyses suggest that evapotranspiration has significantly increased in 60 % of the catchments (p ≤ 0.05) with an average increase of 29 ± 14 mm y−1 decade−1 (±standard deviation) or 4.9 ± 2.3 % decade−1. A pooled pan evaporation series based on 22 stations has, on average, increased by 29 ± 5 mm y−1 decade−1 or 6.0 ± 1.0 % decade−1. Reference evaporation over the 156 catchments estimated by the Penman-Monteith equation has increased by 18 ± 5 mm y−1 decade−1 or 2.8 ± 0.7 % decade−1. Of these, 2.1 % are due to increased global radiation and 0.5 % due to increased air temperature according to the Penman-Monteith equation. A satellite-based vegetation index (NDVI) has increased by 0.02 ± 0.01 decade−1 or 3.1 ± 1.1 % decade−1. Estimates of reference evaporation accounting for changes in stomata resistance due to changes in NDVI indicate that the increase in vegetation activity has led to a similar increase in reference evaporation as changes in the climate parameters. A regression between trends in evapotranspiration and precipitation, as a proxy of soil moisture, yields a sensitivity of 0.30 ± 0.04 mm y−2 increase in evapotranspiration to 1  y−2 increase in precipitation. A synthesis of the data analyses suggests that 38 ± 13 % of the observed increase in catchment evapotranspiration can be directly attributed to increased atmospheric demand and available energy, 30 ± 12 % to increased vegetation activity, and 32 ± 5 % to increased soil moisture due to increases in precipitation.

scholarly journals Components of near-surface energy balance derived from satellite soundings – Part 1: Net available energy

2010 ◽  
Vol 10 (6) ◽  
pp. 14387-14415
Author(s):  
A. Jarvis ◽  
K. Mallick ◽  
G. Wohlfahrt ◽  
C. Gough ◽  
T. Hirano ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Surface Radiation ◽  
Energy Estimates ◽  
Net Radiation ◽  
Heat Accumulation ◽  
Ground Truth Data ◽  
Near Surface ◽  
Available Energy

Abstract. This paper introduces a method for recovering global fields of near-surface net available energy (the sum of the sensible and latent heat flux or the difference between the net radiation and surface heat accumulation) using satellite visible and infra-red products derived from the AIRS (Atmospheric Infrared Sounder) and MODIS (MOderate Resolution Imaging Spectroradiometer) platforms. The method focuses on first specifying net surface radiation by considering its various shortwave and longwave components. This was then used in a surface energy balance equation in conjunction with satellite day-night surface temperature difference to derive 12 h discrete time estimates of surface system heat capacity and heat accumulation, leading directly to a retrieval for surface net available energy. Both net radiation and net available energy estimates were evaluated against ground truth data taken from 30 terrestrial tower sites affiliated to the FLUXNET network covering 7 different biome classes. This revealed a relatively good agreement between the satellite and tower data, with a pooled root mean square deviation of 98 and 72 W m−2 for net radiation and net available energy, respectively, with little bias particularly for the net available energy.

scholarly journals Hydrophytometeorological indexes of Virginia type tobacco

2008 ◽  
Vol 53 (2) ◽  
pp. 91-97 ◽  
Author(s):  
Miroljub Aksic ◽  
Nebojsa Deletic ◽  
Nebojsa Gudzic ◽  
Slavisa Gudzic ◽  
Slavisa Stojkovic
Keyword(s):  
Air Temperature ◽  
Water Consumption ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Global Radiation ◽  
Precipitation Amount ◽  
Soil Layer ◽  
Vegetation Period ◽  
Air Humidity ◽  
Type Water

The field trial of Virginia type tobacco (Hevesi-9) was set in irrigation conditions, in the vicinity of Brzi Brod village, Nisava River's valley, on the alluvium soil type. Water consumption for evapotranspiration, at the irrigated variant and the control one, was calculated for each month and the whole vegetation period, by making the balance between water consumption from the soil layer to 2m under the ground, total precipitation amount in the vegetation and water added by irrigation. Hydro-phyto-meteorological indexes of Virginia type tobacco were calculated in regard to air temperature, relative air humidity, air humidity deficiency, sunshine duration and global radiation. Among the six meteorological elements (the above mentioned five and wind speed) analyzed in the studied period, the highest level of correlation with tobacco ETP was shown by air temperature (r=0.88), so the use of hydro-phytotermic index could be recommended for calculation of potential evapotranspiration in irrigation practice.

scholarly journals Consumptive use pattern of mustard (Brassica Juncea L) under different soil and climatic environments

MAUSAM ◽  
2022 ◽  
Vol 46 (3) ◽  
pp. 245-252
Author(s):  
A. CHOWDHURY ◽  
H. P. DAS ◽  
S. D. GAIKWAD
Keyword(s):  
Soil Moisture ◽  
Energy Balance ◽  
Brassica Juncea ◽  
Global Radiation ◽  
North India ◽  
Soil Types ◽  
Consumptive Use ◽  
Plant Uses ◽  
Climatic Environment ◽  
Important Cash Crop

Mustard is an important cash crop in north India where it is widely grown under different climatic environment and soil types. In the present study, evapotranspiration and other agro-meteoralogical data for four agroclimatic locations, viz., Jorhat, Samakhunta, Raipur and Jodhpur have been utilized to understand consumptive use and related aspects of mustard. The evapotranspiration values recorded by  lysimeters, global radiation and actual soil moisture data of Jorhat and the computed soil moisture have been used.               The study suggests that the nlustard plant uses n10re water at all the stations except at humid location where consumptive use is least. The utilization is n1aximum betw~n 31-60 days after sowing in case ofJorhat l;er 111 and Samakhunta. The con1puted soil 1110isture estimates for 45 cm layer agree with the actual soil moisture. 15-1 The analysis also brings oUt that during the seventh week after sowing, the ratio of consumpiive use and rti. Ru Ilobal radiation attains a nlaxin1um value. This infonnation can be used for detennining irrigation needs and ular m computing energy balance components in the crop. ncymodsE..C.1..S.l.R...llC  

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.

scholarly journals Components of near-surface energy balance derived from satellite soundings – Part 1: Noontime net available energy

2015 ◽  
Vol 12 (2) ◽  
pp. 433-451 ◽  
Author(s):  
K. Mallick ◽  
A. Jarvis ◽  
G. Wohlfahrt ◽  
G. Kiely ◽  
T. Hirano ◽  
...  
Keyword(s):  
Energy Balance ◽  
Surface Energy ◽  
Surface Energy Balance ◽  
Surface Radiation ◽  
Net Radiation ◽  
Heat Accumulation ◽  
Simple Method ◽  
Ground Truth Data ◽  
Near Surface ◽  
Available Energy

Abstract. This paper introduces a relatively simple method for recovering global fields of monthly midday (13:30 LT) near-surface net available energy (the sum of the sensible and latent heat flux or the difference between the net radiation and surface heat accumulation) using satellite visible and infrared products derived from the AIRS (Atmospheric Infrared Sounder) and MODIS (MODerate Resolution Imaging Spectroradiometer) platforms. The method focuses on first specifying net surface radiation by considering its various shortwave and longwave components. This was then used in a surface energy balance equation in conjunction with satellite day–night surface temperature difference to derive 12 h discrete time estimates of surface system heat capacity and heat accumulation, leading directly to retrieval for surface net available energy. Both net radiation and net available energy estimates were evaluated against ground truth data taken from 30 terrestrial tower sites affiliated with the FLUXNET network covering 7 different biome classes. This revealed a relatively good agreement between the satellite and tower data, with a pooled root-mean-square deviation of 98 and 72 W m−2 for monthly 13:30 LT net radiation and net available energy, respectively, although both quantities were underestimated by approximately 25 and 10%, respectively, relative to the tower observation. Analysis of the individual shortwave and longwave components of the net radiation revealed the downwelling shortwave radiation to be main source of this systematic underestimation.

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