Abstract: The non-hydrostatic mesoscale model ARPS 5.0IHOP5 was used to simulate the background wind field in the atmospheric boundary layer over Beijing-Tianjin area. As a comparison, the wind-field diagnostic analysis with observed meteorological data was used to generate hourly wind field in the lower atmosphere in August 2004. The results show that two mesoscale circulations affect this area, they are sea-land breeze and mountain-valley breeze. The mountain-valley breeze may influence the whole plain area, and the influence of sea-land breeze can reach as far as 100km approximately into the inland. Under the influence of these two circulations, the dominant wind is southerly from afternoon to midnight, and then changes to northerly till forenoon. During the period of switching from southerly to northerly, a belt of convergence occurs in the front of the western mountains in the model domain.

Key words: mesoscale model ARPS, mountain-valley breeze, sea-land breeze, Beijing-Tianjin area

摘要： 用非静力平衡的中尺度模式ARPS 5.0IHOP5，模拟京津地区夏季边界层大气的背景 流场，同时用风场诊断模式和实际观测资料获取该地区2004年夏季1个月（8月）的逐时低 层大气流场，作为模拟结果的比对。通过对模拟流场的分析，得出以下结论：京津地区夏季 受昼夜循环的山谷风、海陆风影响明显，山谷风的最大影响范围可以覆盖区域内的平原地区 ，海陆风的影响可以伸展入陆地100km左右。在这两个环流的影响下，区域内主导风 向出现更替，下午至上半夜主导风向为偏南风，下半夜至上午为偏北风。凌晨风向更替过程中可以 在山前出现一条汇聚带。

关键词: ARPS中尺度模式, 山谷风, 海陆风, 京津地区