利用设置于江西省南昌县的新型高精度自动蒸渗仪,于2007年9月1日至2008年8月31日的实测陆面实际蒸散发过程,检验了面蒸散发互补关系模型CRAE(Complementary Relationship Areal Evapotranspiration)、GG模型(Granger-Gray)、平流—干旱模型AA(Advection-Arid ity)3个逐日路面实际蒸散发模型在不同时间尺度上的计算精度,并对计算误差的影响因素进行了讨论。结果表明:该地区实测年蒸散发量为746.1 mm,采用各模型的推荐经验参数对该地区蒸散发的估算结果误差较大,普遍干旱条件下蒸散发的计算值比观测值偏小,而湿润条件下的计算值偏大。通过对各模型的经验参数进行调整,各模型对年蒸散发量的计算精度大为提高,但逐日蒸散发过程的计算精度改进效果有限,在7日的时间尺度上,计算结果显著优于逐日的计算结果,在此时间尺度下,AA模型仍存在一定的系统误差,CRAE模型的估算精度相对较差,GG模型的总体计算效果相对最好。根据与蒸渗仪观测结果的对比分析,根据区域特征进行参数调整后的模型,需要在7日及更长时间尺度上,蒸散发模型的估算结果较为可靠。上述研究对全面认识陆面实际蒸散发特征、理解各蒸散发模型在不同时间尺度上的模拟能力、正确认识气候变化条件下的水循环特征具有重要意义。
With the newly-designed high resolution lysimeter installed in Nanchang County of Jiangxi Prov- ince, the observed overland actual evapotranpiration (ETa ) from September 1, 2007 to August 31,2008 is used to validate three daily ETa model, i. e. CRAE (Complementary Relationship Areal Evapotranspiration), GG (Grang- er-Gray) and AA (Advection-Aridity) models on different time scales, and the model error is also discussed. The results show that the observed annual average ETa is 746.1 ram, while the error of calculated ETa by models with the original parameters is quite large. Calculated ETa of the three models is smaller than the observed value in dry condition and larger than the observation in moisture condition. The models with calibrated parameters show better predictability than the original ones, yet the improvement in daily calculation is limited. Calculation on a 7-day time scale is remarkably better than daily values: there is a systematic error for AA model, and RMSE of CRAE model is fairly large, yet GG model is relatively the best. According to the comparison with the observations of the lysimeter, locally calibrated models would show reliable results on 7-day or longer time scale. The above-mentioned research is of great importance in full understanding of ETa process, of predictability of models on different time scales and of the water cycle character under climate change condition.