【作者】 刘振；

【导师】 潘益农；

【作者基本信息】 南京大学 ， 气象学， 2012， 硕士

【摘要】 利用中尺度数值模式WRF,首先模拟研究了环太湖地区土地利用变化主要是城市化对局地气候的影响,然后进一步研究了土地利用变化对局地环流的影响,结果表明：环太湖区域土地利用变化主要表现为城市扩张。城市化使地表净短波辐射通量增大,潜热通量减小,地表温度升高,感热通量增大。对近地面水平风场的影响主要表现为对近地面风场的摩擦减弱。城市化地区上升运动增强,积云性降水增多；在老城区和城市化郊区下沉速度增大,积云性降水减少。层云降水的改变集中在累积层云降水的大值区且多呈带状分布,与城市扩张位置没有明显关系。总降水在城市化区域增多,在旧城区和郊区减少,积云性降水占总降水的比例增大。局地土地利用变化带来的非局地气候效应在空间分布上具有较好的一致性,即土地利用没有变化的区域的总降水变化与潜热通量、感热通量和地表温度变化的空间分布大致吻合。城市化使得旧城区和郊区气温在夜间略有增大,使城区最高气温出现时间向后推迟。对比分析城市和郊区能量通量的日变化情况,得出城市扩张使得潜热通量减小,感热通量和土壤热通量增大,地表温度和近地面气温升高。在低层大气,太湖湖面存在一个明显的气流辐散。城市扩张对低层垂直速度的水平分布的影响并不明显,对低层水平风场的影响主要表现为城市化区域周围存在向市区辐合的风矢量差,并且城市越大辐合越明显。环太湖地区湖陆风环流与城市热岛环流的相互作用表现为湖陆风环流在伸展到市区之前垂直速度都是增强的,进入市区之后受热岛环流的影响开始减弱,到达热岛环流上升气流的位置时,湖陆风环流又重新增强,并与城市热岛环流叠加在一起,产生一个较大的垂直速度。城市化对局地环流的影响主要是对城市热岛环流的影响,对湖陆风环流并没有明显的直接影响。更多还原

【Abstract】 Using the mesoscale model WRF, a series of numerical simulations were performed over the area around Taihu Lake of China. Numerical simulations were firstly carried out to study the local climate response to land use change. Then the local circulation response to land use change were simulated. The simulation results show that:Urbanization is the dominant type of land use change. Net short wave radiation fluxes, ground surface temperatures, and sensitive heat fluxes increase in the urbanized areas, while latent heat fluxes decrease. A decline of wind speed is found in the urbanized areas. Moreover, the lake breeze and urban heat island circulations enhance. Consequently, increased cumulus precipitation occurred in urbanized areas due to the additional vertical velocity, while convection and cumulus precipitation in old town and suburban were inhibited. Stratiform precipitation changes were concentrated in large stratiform rainfall areas. Total precipitation increased in urbanized area and decreased in old town and suburbs, with the proportion of convective precipitation rising. In areas with no land use change, the pattern of precipitation change coincided quite well with the pattern of surface energy flux change.Urbanization makes the old town and suburban temperatures increased slightly during the nighttime, and the highest temperature of old town postponed. The comparative analysis of the diurnal variation of the urban and suburban energy fluxes obtained that urban expansion makes the latent heat flux decreased while sensible heat flux and soil heat flux increases, so the surface temperature and near-surface temperatures rise. There is a clear divergence over Taihu lake in the lower atmosphere. The effect of the urban expansion on low-level vertical velocity distribution is not obvious. There is a convergence of wind vector change around the urbanized area and the larger the city is, the more obvious the convergence is. The vertical velocity of the lake breeze circulation is enhanced by time before entering the city, then suppressed by urban heat island circulation when in the city, and enhanced again and combined with the heat island circulation when reaching the updraft of the heat island circulation. The effect of Urbanization is mainly on urban heat island circulation, and there is no obvious direct impact on the lake breeze circulation.更多还原