Yang Fu-Lin, Zhang Qiang, Wang Run-Yuan, Wang Sheng, Yue Ping, Wang He-Ling, Zhao Hong
Gansu Province Key Laboratory of Arid Climatic Change and Reducing Disaster/China Meteorological Administration Key Open Laboratory of Arid Climatic Change and Disaster Reduction, Institute of Arid Meteorology, China Meteorological Administration, Lanzhou 730020, China.
Ying Yong Sheng Tai Xue Bao. 2013 May;24(5):1209-14.
Evapotranspiration (ET) is an important component of ground surface energy balance and water balance, and closely related to water cycle. By using eddy covariance technique, this paper studied the ET characteristics of agroecosystems in the semi-arid area of Loess Plateau in growth season (from April to September), 2010, and analyzed the relationships between crop coefficient and environmental factors. During the observation period, the diurnal variation of latent heat flux (LE) in each month was similar to single-peak curve, and the peak value (151.4 W x m(-2)) occurred in August. The daytime energy partitioning manner showed a significant seasonal variation, with LE/R(n) < H/R(n) (R(n) was net radiation, and H was sensible heat flux) from April to June, and LE/R(n) > H/R(n) from July to September. The daily ET rate also showed a significant seasonal variation, with the maximum of 4.69 mm x d(-1). The wind speed (W(s)), relative humidity (RH), soil water content (theta), and atmospheric vapor pressure deficit (D) were the major factors affecting the crop coefficient K(c) which was exponentially decreased with increasing W(s), exponentially increased with increasing RH and theta, and linearly decreased with increasing D.
蒸散（ET）是地表能量平衡和水分平衡的重要组成部分，与水循环密切相关。本文利用涡度相关技术研究了2010年黄土高原半干旱区生长季（4月至9月）农业生态系统的蒸散特征，并分析了作物系数与环境因子之间的关系。观测期内，各月潜热通量（LE）的日变化均呈单峰曲线，峰值（151.4 W·m-2）出现在8月。白天能量分配方式呈现出明显的季节变化，4月至6月LE/R(n) < H/R(n)（R(n)为净辐射，H为感热通量），7月至9月LE/R(n) > H/R(n)。日蒸散速率也呈现出明显的季节变化，最大值为4.69 mm·d-1。风速（W(s)）、相对湿度（RH）、土壤含水量（θ）和大气水汽压差（D）是影响作物系数K(c)的主要因素，K(c)随W(s)增加呈指数下降，随RH和θ增加呈指数上升，随D增加呈线性下降。
