辐射模型不同率定方法总辐射数据缺失插补比较

Comparison of Different Calibration Methods on ngstrm-Presscott Model for Missing Data Interpolation

在长期连续观测中,总辐射(Rs)的观测数据通常有不同程度的缺失。基于日照时数的ngstrm-Presscott(AP)模型是一种广泛应用且精度较高的总辐射估算经验模型。选取A-P模型3种不同参数率定方法 (M1:每年率定,M2:分月率定,M3:多年率定),基于6个辐射站的辐射资料,对年平均Rs、年平均ET0、参数取值和插补精度进行了比较。t检验结果表明,3种方法下A-P模型在昌都站数据插补无明显差异,Rs年际变化大是造成该站Rs模拟不准的主要原因。在宜昌和南宁站,M1方法进行数据插补精度高于其他方法,M1方法 Rs缺失天数分别为40 d和70 d时,两站计算的参考作物蒸发蒸腾量(ET0)与实测Rs计算的ET0相比,t检验无明显差异。M2与M3相比精度稍高,但在昆明、赣州、杭州和南宁站冬季精度更高且6—8月份精度更低。与1990年以前相比,各站点A-P模型参数a在1990年以后有明显上升,工业污染导致气溶胶增加是原因之一。A-P模型在极端年份率定精度不高,在极端炎热气候年份,应用该模型用于灌溉预报时会低估作物耗水量,可能会给决策带来风险。该研究结果可用于A-P模型的风险评估和提高总辐射时间序列数据缺失情况下的插补精度。

In the long-term continuous observation,observed data of global solar radiation（ Rs） usually has different degrees of missing. ngstrm-Presscott（ A-P） model,which was based on sunshine hours,is a widely used empirical model that has high precision. Three different parameters calibrated methods for A-P model were chosen,which were annually（ M1）,monthly（ M2） and yearly（ M3） calibrated by only one time. Radiation data from six radiation stations were used,which were Changdu,Yichang,Kunming,Ganzhou,Hangzhou and Nanning stations. Annual average Rs,annual average reference crop evapotranspiration（ ET0） and parameter selection were compared by the three methods,at last,three stations were selected for interpolation accuracy evaluation. The results were as follow： t-test results showed that no difference among the three methods in use of data interpolation in Changdu station,severe changes of Rsinter annual was the main reason for poor accuracy. The accuracy of M1 method for data interpolation was higher than those of other methods in Yichang and Nanning stations. When missing datawere 40 d and 70 d,there were no difference between M1 method calibrated and measured values of Rsin calculating ET0,but when the missing data was over 20 d,M2 and M3 methods showed significant difference between estimated and measured Rs,its influence on calculating ET0 was the same. Compared with the calibration method for many years,the monthly calibrated method had a little higher precision in estimating Rs,with higher precision in winter and lower precision from June to August in Ganzhou,Hangzhou,Kunming and Nanning stations. Compared with the results before 1990,the parameter a of A-P model was increased dramatically in all stations after 1990,industrial pollution led to an increased aerosol was one of main reasons. In extremely hot year,the accuracy of A-P model was lower than that in normal year,application of the model to irrigation forecast would underestimate crop water consumption,which may bring risk for decision-making. The results can be used in A-P model for risk assessment and improving the total radiation time series data of the interpolation precision of missing cases.