CLM4.5在西北农牧交错带盐池站的模拟性能评估

Evaluation of Simulation Performance of CLM4.5 at the Yanchi Station in the Agricultural-Pastoral Ecotone of Northwest China

农牧交错带具有草地、裸地、农田大面积相互镶嵌的独特下垫面,其地表水热过程变化复杂,亟需深入研究。利用宁夏盐池站2017年实际观测资料,对陆面过程模式CLM4.5的模拟性能进行检验。结果表明,在复杂下垫面下,CLM4.5仍能较好地模拟出草地的地面反射辐射、地面长波辐射和净辐射以及0~10 cm土壤含水量和温度的变化特征,但模拟值与观测值还存在一定偏差。CLM4.5能模拟出辐射通量的日变化特征,除5月外,地面反射辐射模拟值与观测值之间的偏差较小。地面长波辐射模拟值白天偏高,净辐射观测值与模拟值的相关系数为0.99,均方根误差为22.50 W·m^-2。土壤含水量观测值与模拟值的相关系数达0.83,但模拟值偏低,且模式对降雨后土壤含水量变化过程的模拟性能有待提高。土壤温度模拟值的日变化特征较为明显,观测值与模拟值的相关系数为0.98,均方根误差为2.82℃。

The agricultural-pastoral ecotone is a mosaic of grassland, barren land and cropland, and there is complex energy and water exchange and interactions over land surface. The applicability of CLM4.5 was evaluated using the observed data of Yanchi station in the agricultural-pastoral ecotone of Northwest China in 2017. The results indicated that CLM4.5 simulated the reflection radiation, upward longwave radiation, net radiation, soil moisture and temperature at the 0-10 cm depth well over the grassland in the complex land surface mosaic, while there were deviations between the simulated values and observed values. The CLM4.5 could reproduce diurnal variation of surface radiation fluxes. The deviations between the observed and simulated values of the reflective radiation were small except those in May. The simulated values of the upward longwave radiation were higher than the observed values during the daytime. The correlation coefficient between the simulated and observed values of net radiation was 0.99, and root-mean-square-error(RMSE) was 22.50 W·m^-2. The correlation coefficient between the simulated and observed values of soil moisture water content was 0.83. However, CLM4.5 underestimated the soil moisture and had an unsatisfactory performance of the simulated soil moisture after precipitation events. CLM4.5 simulated diurnal variations of the soil temperature well. The correlation coefficient between the simulated soil temperature and observed values was 0.98, and RMSE was 2.82 ℃.