Bowen ratio/energy balance technique for estimating crop net CO2 assimilation, and comparison with a canopy chamber

1990 ◽  
Vol 42 (4) ◽  
pp. 203-213 ◽  
Author(s):  
A. A. Held ◽  
P. Steduto ◽  
F. Orgaz ◽  
A. Matista ◽  
T. C. Hsiao
Keyword(s):  
Energy Balance ◽  
Bowen Ratio ◽  
Co2 Assimilation ◽  
Net Co2 Assimilation ◽  
Balance Technique ◽  
Ratio Energy ◽  
Canopy Chamber

An evaluation of the water balance technique for the estimation of evapotranspiration for a mixed forest

1991 ◽  
Vol 21 (11) ◽  
pp. 1622-1631 ◽  
Author(s):  
T. N. Papakyriakou ◽  
J. H. McCaughey
Keyword(s):  
Energy Balance ◽  
Water Balance ◽  
Mixed Forest ◽  
Bowen Ratio ◽  
Integration Period ◽  
Evapotranspiration Rate ◽  
Minimum Number ◽  
Balance Technique ◽  
Time Required ◽  
Ratio Energy

In the summer of 1987 a detailed field experiment was conducted at the Petawawa National Forestry Institute at Chalk River, Ontario, to evaluate the performance of the water balance technique for the estimation of evapotranspiration. Bowen ratio – energy balance estimates of evapotranspiration, available over a portion of an intensive measurement period, provided an independent check on the water balance estimates. The daily totals of evapotranspiration were on average 1% less than the Bowen ratio – energy balance estimate. The length of time required to maintain the evapotranspiration estimates below a 10% level of uncertainty using the water balance technique is 13 days. The lowest average daily percent probable error is obtained for an integration period with (i) a minimum number of precipitation events, (ii) a large number of days, and (iii) a high evapotranspiration rate.

BOWEN RATIO-ENERGY BALANCE ESTIMATES OF EVAPOTRANSPIRATION AND CROP COEFFICIENT FOR TOMATO PLANTS

1996 ◽  
pp. 121-126
Author(s):  
A.M.R. Abdel-Mawgoud ◽  
S.O. El-Abd ◽  
A.F. Abou-Hadid ◽  
T.C. Hsiao
Keyword(s):  
Energy Balance ◽  
Crop Coefficient ◽  
Bowen Ratio ◽  
Tomato Plants ◽  
Ratio Energy

scholarly journals Bower ratio-energy balance associated errors in vineyards under dripping irrigation

2007 ◽  
Vol 22 (2) ◽  
pp. 233-240 ◽  
Author(s):  
José Monteiro Soares ◽  
Pedro Vieira De Azevedo ◽  
Bernado Barbosa Da Silva
Keyword(s):  
Energy Balance ◽  
Soil Surface ◽  
Field Measurements ◽  
Bowen Ratio ◽  
Global Solar Radiation ◽  
Soil Heat Flux ◽  
Vitis Vinifera L ◽  
Data Logger ◽  
And Storage ◽  
Ratio Energy

This study was conducted at the Bebedouro Experimental Station in Petrolina-PE, Brazil, to evaluate the errors associated to the application of the Bowen ratio-energy balance in a 3-years old vineyard (Vitis vinifera, L), grown in a trellis system, irrigated by dripping. The field measurements were taken during fruiting cycle (July to November, 2001), which was divided into eigth phenological stages. A micrometeorological tower was mounted in a grape-plants row in which sensors of net radiation, global solar radiation and wind speed were installed at about 1.0 m above the canopy. Also in the tower, two psicometers were installed at two levels (0.5 and 1.8 m) above the vineyard canopy. Two soil heat flux plates were buried at 0.02 m beneath the soil surface. All these sensors were connected to a Data logger 21 X of Campbell Scientific Inc., programmed for collecting data once every 5 seconds and storage averages for every 15 minutes. A comparative analysis were made among four Bowen ratio accepting/rejecting rules, according to the methodology proposed by Spano et al. (2000): betar1 - values of beta calculated by Bowen (1926) equation; betar2 - values of beta as proposed by Verma et al. (1978) equation; betar3 - exclusion of the beta values obtained as recommended by Unland et al. (1996) and betar4 - exclusion of the beta values calculated as proposed by Bowen (1926), out of the interval (-0.7 < beta < 0.7). Constacted that the Unland et al. (1996) and Soares (2003) accepting/rejection rules were better than that of Verma et al. (1978) for attenuating the advective effects on the calculations of the Bowen ratio. The comparison of betar1 with betar2 rules showed that the statistical errors reaching maximum values of 0.015. When comparing betar1 with betar3 e betar4, the beta errors reaching maximum values of 5.80 and 3.15, respectively.

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