区域气候模式(RegCM2)与水文模式耦合的数值试验

建立不均匀的地表径流算法，修改RegCM2的径流方案，设计了一个适合与气候模式RegCM2耦合、能模拟水文站流量的汇流模式，模拟了1998年6、7、8月降水的空间分布，分析了该径流方案对降水、地表热量通量、地表径流、土壤湿度产生的影响。结果表明：（1）该方案在模拟1998年长江流域降水空间分布上有一定的合理性，在一定程度上改善了降水量的模拟，其影响大致是总降水量的10％；（2）地表径流方案改变了地面向大气输送的热量通量，这种作用随时间发生变化，这种变化与地表水分的再分配有关；（3）本方案计算的土壤渗透率较强，在暴雨初期，产生径流较少，而在暴雨后期土壤湿度增大，产生的地表径流较大，这一点更符合洪水形成的特点；（4）水文一气候耦合模式模拟了两个长江水文站的流量，模拟值基本反映了实测值的变化趋势，也表明耦合模式基本能反映1998年夏季长江流域大暴雨期间的地表水文过程。

Numerical Experiment of the Coupling of RegCM2 and a Hydrological Model

Replacing the RegCM2 runoff scheme with the heterogeneous surface runoff algorithm which is suitable to the loosen and compact soils,this paper designs a hydrological model being coupled with RegCM2,and simulates the discharges of the two important hydrological stations in the Yangtze basin,which are verified by the observation value.The monthly precipitation of June,July and August 1998 during the rain storms is simulated by the coupling model,and the impact of the runoff scheme on simulated precipitation,surface heat fluxes,runoff and soil moisture is analyzed.The results show that(1) the runoff scheme is reasonable for simulating the precipitation distribution during the rain storms in 1998,and improves to some extent precipitation simulation,about 10% of total precipitation;(2)the runoff scheme changes timely the heat fluxes from the surface to the atmosphere which are connected with the reassignment of the surface water;(3)this scheme enhances the soil infiltration,resulting in less runoff during the early period of rainstorm,and more runoff during the last period;(4)the consistency of simulated and observed discharges shows that the coupling model has capacity to represent the hydrological process in the Yangtze basin during the heavy rainstorms in 1998.