本文利用NCAR开发的CAM5.1(Community Atmosphere Model Version 5.1)模式,针对我国东部大规模城市下垫面发展对南海夏季风爆发的影响进行了数值模拟研究。结果表明我国东部大规模城市群发展可能使得南海夏季风提前1候爆发;机理分析表明:在南海夏季风爆发之前,中国东部城市群发展引起的陆面增温,使得南海及其附近地区南北温差提前逆转、中国东部区域海平面气压降低,导致中南半岛到南海地区西南气流加强,中南半岛到南海地区降水增加,而凝结潜热垂直变化强迫出的异常环流,促进了南亚高压的加强及提前北跳,相伴随的高层抽吸作用有助于季风对流的建立和西太平洋副高的减弱东撤,从而形成了有利于南海夏季风爆发的高低层环流条件,导致南海夏季风提前爆发。另外,观测结果表明1993年之后南海夏季风爆发的日期相对上一个年代明显提前约2候,城市化快速发展阶段与南海夏季风爆发的年代际变化存在时间段的吻合,表明城市下垫面发展可能是南海夏季风提前爆发的原因之一。 相似文献
In the numerical simulation of groundwater flow, uncertainties often affect the precision of the simulation results. Stochastic and statistical approaches such as the Monte Carlo method, the Neumann expansion method and the Taylor series expansion, are commonly employed to estimate uncertainty in the final output. Based on the first-order interval perturbation method, a combination of the interval and perturbation methods is proposed as a viable alternative and compared to the well-known equal interval continuous sampling method (EICSM). The approach was realized using the GFModel (an unsaturated-saturated groundwater flow simulation model) program. This study exemplifies scenarios of three distinct interval parameters, namely, the hydraulic conductivities of six equal parts of the aquifer, their boundary head conditions, and several hydrogeological parameters (e.g. specific storativity and extraction rate of wells). The results show that the relative errors of deviation of the groundwater head extremums (RDGE) in the late stage of simulation are controlled within approximately ±5% when the changing rate of the hydrogeological parameter is no more than 0.2. From the viewpoint of the groundwater head extremums, the relative errors can be controlled within ±1.5%. The relative errors of the groundwater head variation are within approximately ±5% when the changing rate is no more than 0.2. The proposed method of this study is applicable to unsteady-state confined water flow systems.
