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首页> 外文期刊>Irrigation Science >Accuracy of the Bowen ratio-energy balance method for measuring latent heat flux in a semiarid advective environment
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Accuracy of the Bowen ratio-energy balance method for measuring latent heat flux in a semiarid advective environment

机译：鲍文比能量平衡法在半干旱对流环境中测量潜热通量的准确性

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摘要

The Bowen Ratio-Energy Balance (BREB) is an accurate method often used to measure the latent heat flux (λE) due to its simplicity and portability. However, its performance in advective areas is less clear and its accuracy may depend on the equality of eddy transfer coefficients for heat and water vapor. In this work, hourly measured λE of a reference crop (Festuca arundinacea Schreb.) using a BREB system was compared with lysimeter-measured λE under moderate to severe advective conditions. The lysimeter resolution for hourly records was 22.6 W m?2. The analysis of the eddy transfer coefficients was made using simultaneous measurements of fluxes and vertical gradients of temperature and humidity. To avoid computational problems when β→ ?1, some hourly periods were discarded in the analysis. Rejected data amounted to 37% of the total, although the cumulative evapotranspiration (ET) during these hours did not exceed 13% of the total ET. The BREB method overestimated daily ET by an average of 5.5% and by 5.7% when only daylight hours were considered. Under stable atmospheric conditions the method was less accurate, with relative errors of 21% vs. 11% under unstable conditions. For daylight hours, accuracy was higher under unstable conditions (RMSE = 36.15 W m?2) than under stable conditions (RMSE = 50.20 W m?2), which had larger overestimations of ET (6.3 vs. 5.1%). The main source of error appears to come from insufficient fetch resulting in local advective conditions. Nevertheless, and from a purely practical perspective, under the advective conditions of these measurements the BREB technique provides accurate ET fluxes with limited errors.
机译：鲍文比能量平衡（BREB）是一种精确的方法，由于其简单性和便携性，经常用于测量潜热通量（λE）。但是，其在平流区的性能尚不清楚，其准确性可能取决于热量和水蒸气的涡流传递系数的相等性。在这项工作中，将使用BREB系统每小时测量的参考作物（Festuca arundinacea Schreb。）的λE与在中等至严重对流条件下用溶渗仪测得的λE进行了比较。每小时记录的溶血计分辨率为22.6 W m？2 。使用同时测量通量和温度和湿度的垂直梯度进行涡流传递系数的分析。为了避免β→α1时的计算问题，在分析中舍弃了一些小时周期。拒绝的数据占总数的37％，尽管在这些小时内的累积蒸散量（ET）不超过总ET的13％。如果仅考虑白天，则BREB方法平均将每日ET高估了5.5％，而将其高估了5.7％。在稳定的大气条件下，该方法的准确性较差，相对误差为21％，而在不稳定条件下为11％。对于白天，在不稳定条件下（RMSE = 36.15 W m？2 ）的准确度要高于在稳定条件下（RMSE = 50.20 W m？2 ）的准确度，后者具有较高的ET高估（6.3 vs 5.1％）。错误的主要来源似乎是由于获取不足导致局部对流条件。但是，从纯粹的实际角度来看，在这些测量的平流条件下，BREB技术可提供准确的ET通量，且误差有限。

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    《Irrigation Science》 |2007年第2期|127-140|共14页
  • 作者

    P. Gavilán; J. Berengena;

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    IFAPA área de Producción Ecológica y Recursos Naturales Centro de Investigación y Formación Agraria “Alameda del Obispo” Avd. Menéndez Pidal s 14004 Córdoba Spain;

    IFAPA área de Producción Ecológica y Recursos Naturales Centro de Investigación y Formación Agraria “Alameda del Obispo” Avd. Menéndez Pidal s 14004 Córdoba Spain;

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