Budyko-Fu模型下气候季节性指标中水热变化时相差的选取研究

Selection of time-phases of water and heat in climateseasonality indexes under Budyko-Fu model

流域水热耦合过程研究中,Budyko理论近年来得到了广泛的应用,其中又以傅抱璞公式(Budyko-Fu)比较著名。本研究在Budyko-Fu模型下,对其控制性参数ω与3种气候季节性指标的关系分别进行了分析。3种气候季节性指标包括 SI1 —考虑年内月降水量距平特征, SI2 —考虑用正弦曲线模拟降水量与潜在蒸散季节变化时各自的振幅差别特征,以及 SAI —在 SI2 的基础上进一步考虑降水量与潜在蒸散季节变化的相位差别。文章探讨了 SAI 指标计算中降水量与潜在蒸散季节相位取值年际变化与否的影响,由此形成 SAI1和SAI2 两个指标;随后比较了不同气候季节性指标在径流变化模拟中的应用效果。结果表明,在流域尺度水热耦合年际过程分析中,若气候季节性指标采用 SAI2,即同一流域水热变化时相差由多年平均状况确定,且年际间保持不变,则效果较好;由此季节性指标结合NDVI数据给出的参数ω半经验公式的决定系数( R 2)达到了0.746。在此基础上应用Budyko-Fu公式,流域年径流量的模拟精度显著提高。

Budyko models have been widely used in studying the catchment water-heat coupling process in recent years,among which Budyko-Fu model received greater attentions.Taking Jinghe River on the Loess Plateau as an example,the relationship between the controlling parameter,ω,in Budyko-Fu model and three climate seasonality indexes were analyzed in this study.The three climate seasonality indexes included SI1 -considering the monthly precipitation departure in a year, SI2 -considering the amplitude difference between seasonal variations of precipitation and potential evapotranspiration by sinusoidal simulation,and SAI -considering the time-phase differences between seasonal variations of precipitation and potential evapotranspiration on the basis of SI2 .Then,the impact of time-phases change of both precipitation and potential evapotranspiration on the calculation of SAI was discussed,so there were two indexes, SAI1 and SAI2 .Further,the effects of different climate seasonality indexes on streamflow simulation were compared.The results showed that in the analysis of catchment water-heat coupling process,the SAI2 performed well,in which the time-phases of water-heat seasonality were determined by the mean annual precipitation and potential evapotranspiration and remained unchanged from year to year.The coefficient of determination ( R 2) in the semi-empirical equation of ω given by SAI2 and NDVI was 0.746.The simulation accuracy of annual streamflow using this equation was also improved.