基于VIC模型和Palmer干旱指数的区域干旱化评价研究

基于VIC(可变下渗容量)模型的流域网格划分及其对径流、蒸散发和土壤含水量变化的模拟，对Palmer干旱指数各水量平衡分量的计算进行了优化，并采用分级修正的方式，改进了Palmer干旱指数中气候特征系数K的确定方法。在此基础上，建立了基于VIC模型和Palmer干旱指数的区域气候干湿变化评价系统，并将该系统在黄土高原进行了应用。结果表明，近40 a黄土高原气候正向暖干化趋势发展，1990年以后暖干化趋势尤为明显。研究区干旱发生频率在空间上呈由西北向东南递减趋势，不同季节干旱发生频率空间分布存在一定差异。该评价系统物理机制清晰，地区适应性较强，在实时监测和评估气候干湿变化及其时空分布上存在较大应用潜力。

Study on regional drought assessment based on Variable Infiltration Capacity model and Palmer Drought Severity Index

In this study, we created a new climate change estimation system wherein we combined the Variable Infiltration Capacity model for hydrological processes simulation and PDSI for climate change estimation. The simulation results and the grid system of VIC were applied to substitute for the two-layer bucket-type model to do the hydrological accounting in PDSI. Moreover, the determining method of climatic characteristic, K, was optimized using a classified calibration procedure. These measures could greatly improve the physical mechanism of PDSI and expand its application range. This estimation system was applied to a grid system of 293 points with a resolution of 50 km×50 km on the Chinese Loess Plateau. The results show that the Loess Plateau exhibited an overall climatic warming-drying trend between 1970 and 2010, and this trend became increasingly significant, particularly over the past two decades. The drought frequency decreased from northwest to southeast on the Plateau, and there were some differences in the spatial distribution of drought frequency in different seasons. Due to this system having a clearly physical mechanism, and because of its relatively strong regional applicability, this new climate change estimation system is expected to be widely used in monitoring and estimating the spatial-temporal trends of climate change.