Growing season CO2 fluxes in a sagebrush-steppe ecosystem in Idaho: bowen ratio/energy balance measurements and modeling

Actual evapotranspiration was observed by using eddy covariance (EC) technique, calculated by micrometeorological method the Bowen ratio energy balance (BREB) and measured by micro-lysimeter (ML) in the Suli alpine meadow which located in the northeastern edge of Qinghai-Tibet Plateau noted for its high elevation and cold environment during the growing season in 2011. Results showed that the energy balance ratio for half-hour data was 0.74. Without consideration of uncertainty, the evapotranspiration values estimated by BREB, ML, and EC were 270.6 mm, 238.9 mm, and 236.1 mm, respectively. Significant correlation existed between the evapotranspiration results by the three methods. Uncertainties of the evapotranspiration estimation by BREB, ML, and EC were 19.6 mm, 15.6 mm, and 15.1 mm, respectively. Deduced by facts on the natural and vegetation conditions, the value of evapotranspiration should be equal to that of precipitation, that is, about 252 mm. From this point, the evapotranspiration values estimated by the three methods were within a reliable range. The EC method has larger advantage and wider scope for the estimation of evapotranspiration in alpine meadow area.

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

Acta Horticulturae ◽

10.17660/actahortic.1996.434.13 ◽

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

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

Revista Brasileira de Meteorologia ◽

10.1590/s0102-77862007000200008 ◽

2007 ◽

Vol 22 (2) ◽

pp. 233-240 ◽

Cited By ~ 2

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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