各类潜在蒸散发经验估算法具有区域性的特点,实际运用时需要进行修正。常用的修正方法是通过线性回归法对经验公式的计算结果进行修正,并没有将修正反映到经验公式中的系数上。本研究提出一种系数修正的方法,通过逐月误差比例校正来修正经验公式中的参数,称之为误差比例校正法。以FAO推荐的Penman-Monteith法为标准,比较经线性回归法、误差比例校正法2种方法修正前后6种经验估算法(Blaney-Criddle、Hargreaves、Hamon、Makkink、Priestley and Taylor、Rohwer)在闽江流域的计算精度,从而对误差比例校正法的修正效果及稳健性进行探讨。结果表明:逐月误差比例校正法整体上具有较好的修正效果,可以较大程度提高6种经验方法在该区域的计算精度;常用的线性回归法虽计算较误差比例校正法稍复杂,但其修正效果及稳健性略优于误差比例校正法。
Reference evapotranspiration （ETo） is often used to estimate actual evapotranspiration in water balance studies. In this study, the present and future spatial distributions and temporal trends of ETo in the Xiangjiang River Basin （XJRB） in China were analyzed. ETo during the period from 1961 to 2010 was calculated with historical meteorological data using the FAO Penman-Monteith （FAO P-M） method, while ETo during the period from 2011 to 2100 was downscaled from the Coupled Model Intercomparison Project Phase 5 （CMIP5） outputs under two emission scenarios, representative concentration pathway 4.5 and representative concentration pathway 8.5 （RCP45 and RCP85）, using the statistical downscaling model （SDSM）. The spatial distribution and temporal trend of ETo were interpreted with the inverse distance weighted （IDW） method and Mann-Kendall test method, respectively. Results show that： （1） the mean annual ETo of the XJRB is 1 006.3 mm during the period from 1961 to 2010, and the lowest and highest values are found in the northeast and northwest parts due to the high latitude and spatial distribution of climatic factors, respectively; （2） the SDSM performs well in simulating the present ETo and can be used to predict the future ETo in the XJRB; and （3） CMIP5 predicts upward trends in annual ETo under the RCP45 and RCP85 scenarios during the period from 2011 to 2100. Compared with the reference period （1961-1990）, ETo increases by 9.8%, 12.6%, and 15.6% under the RCP45 scenario and 10.2%, 19.1%, and 27.3% under the RCP85 scenario during the periods from 2011 to 2040, from 2041 to 2070, and from 2071 to 2100, respectively. The predicted increasing ETo under the RCP85 scenario is greater than that under the RCP45 scenario during the period from 2011 to 2100.
Xin-e TaoHua ChenChong-yu XuYu-kun HouMeng-xuan Jie
