北京稳定天气条件下城市边界层环流特征数值研究

Numerical Study of Circulation Characteristics in Urban Boundary Layer in Stable Weather in Beijing

采用科罗拉多大学和MRC/ASTER共同开发的区域大气模拟系统(RAMS)对北京地区稳定天气条件下的个例进行数值模拟,通过对数值模拟结果与观测事实的比较以及敏感性试验,分析了北京城市边界层环流特征和环流影响因子在环流发展过程中的作用。结果表明:①在山谷风环流和热岛环流相互作用下形成了北京城市边界层流场特有的局地环流。②热岛中心在决定边界层环流的辐合区位置上起相对较大的作用,边界层环流的强度和发展高度由山谷风强度和热岛强度共同决定。

RAMS （Regional Atmospheric Modeling System, developed by University of CO ＆ MRC/ASTER） was used to study a typical stable case in the Beijing area. By comparing the numerical simulation and observation and carrying out sensitive experiments, the circulation characteristics of the urban boundary layer in Beijing and the impacts of various factors on circulation development were analyzed. The analysis shows that ① the formation and evolution of the local circulation in the urban boundary layer is influenced by the mountain breeze circulation and heat island circulation together. ② The heat island center has relatively significant impact on the location of the convergence zone, while the intensities of mountain breeze and heat island determine jointly the intensity and the evolving height of the boundarY-layer circulation.