干旱气候条件下多种潜在蒸发量估算方法对比研究

Comparison of Different Methods for Estimating Potential Evaporation in an Arid Environment

潜在蒸发量表征局地大气蒸发能力,是研究陆面过程和水文循环的关键参量。基于中国科学院临泽内陆河流域研究站2015 2016年实测气象数据,对比分析了综合法、辐射法和温度法共10种潜在蒸发量计算公式在河西走廊中段干旱气候条件下的差异,并将计算结果与台站内E601型和Φ20型蒸发皿记录的蒸发量数据进行了统计分析。结果表明:(1)影响E601型和Φ20型蒸发量的气象因素主要为饱和水气压差、净辐射和温度;(2)两种蒸发皿折算系数(ETp-E601/ETp-Φ20)的算术平均法和一元线性回归法计算值分别为0.65和0.62;(3)总体上综合法最适用,其次是辐射法,基于温度的各方法适用性最差;(4)综合法中FAO-56法最优,与E601型蒸发皿值拟合值为1.02(R2=0.70);其次是基于辐射的Doorenbos-Pruitt法,与Φ20型蒸发皿值拟合值为0.78(R2=0.85)。以上研究结果为估算我国西北干旱区及类似环境下潜在蒸发量提供了方法上的借鉴。

The potential evaporation indicates the atmospheric evaporative demand under some specific conditions and is one of the key parameters involved in land surface process and hydrological cycle. Combined with the meteorological data and pan evaporation from 2015 to 2016 in the Linze Inland River Basin Research Station,Chinese Academy of Sciences,We selected a total of 10 methods derived from the well-know n radiation-based,temperature-based,and combination methods to estimate the potential evaporation in the middle regions of the Hexi Corridor,northw est China. We compared and analyzed the differences of methods in an arid environment and the results were compared with the data from E601 and Φ20 evaporation pan. The principal results indicated that：（1） We analyzed the relationship between evaporation and meteorological factors and found that the main meteorological factors affecting the evaporation were vapor pressure deficit,net radiation and temperature.（ 2） We used two methods to calculate conversion coefficients of pan. The arithmetic mean method of the conversion coefficients of pan were 0. 65 and the linear regression method of the conversion coefficients of pan were 0. 62.（3）The differences of the calculated values are mainly due to the value of different aerodynamic terms and radiation terms. Every method is based on a specific regional and climatic background and the parameters are also calculated based on experience. The methods need to be corrected when used in other regions. In general,the combination methods are most applicable in this region,follow ed by the radiation-based methods,and the temperaturebased methods have the worst applicability.（4） In the combination methods,the results of the FAO-56 method was the best and the fitting value of E601 evaporation pan was 1. 02（ R^2 was 0. 70）,follow ed by the radiationbased,the results of the Doornbos-Pruitt method fit well with the Φ20 evaporation pan and the fitting value was0. 78（ R^2 was 0. 85）. These provide a reference for estimating evaporation simply and accurately with the help of evaporation pan. In addition,the Blaney-Criddle method and the Hargreaves-Samani method were also fit for calculating potential evaporation in this region. The above results provide support for the accurate estimation of evaporation in regions where the climatic data were insufficient. And they also provide a methodological reference for calculating potential evaporation in the arid or similar conditions to our study site.