北京地区夏季边界层结构日变化的高分辨模拟对比  

Diurnal Cycles of the Boundary Layer Structure Simulated by WRF in Beijing

作　　者：陈炯 王建捷[2] 

机构地区：[1]国家气象中心,北京100081 [2]北京市气象局,北京100089

出　　处：《应用气象学报》2006年第4期403-411,共9页Journal of Applied Meteorological Science

基　　金：科技部国家科技攻关计划"奥运气象保障技术研究"(2002BA904B05);国家气象中心自由项目(ZK2005-09);北京市自然科学基金重点项目(8051002);国家科技攻关计划"北京奥运国际天气预报示范计划关键技术研究"(2003BA904B09)共同资助

摘　　要：使用WRF中尺度数值模式,分别选用两种不同的边界层参数化方案(MYJ,YSU)和3种陆面参数化方案(SLAB,Noah,RUC),对2004年7月1日08:00—7月4日20:00(北京时)北京地区夏季边界层结构进行1 km的高分辨模拟。对比分析了近地面层风场、温度场以及边界层的日变化特征,结果发现:WRF模式基本模拟出了北京夏季边界层的日变化特征;在边界层方案中,MYJ方案描述的边界层结构较YSU方案合理;Noah陆面模式较好地反映了城市的热岛效应;无降水时,风速及边界层高度对于陆面过程不敏感,而降水发生后,陆面过程对于边界层结构的影响增大;各方案模拟的城区风速明显偏大,这是因为没有充分考虑城市建筑物的阻力作用。The planetary boundary layer （PBL） is directly affected by the presence of the earth＇s surface, responding to such forcing as frictional drag, solar heating and evapotranspiration. The PBL over land generally undergoes significant diurnal cycles. The daytime PBL develops when the upward net surface heat flux increases after sunrise. The mass and wind fields in this mixed layer adjust quickly to produce a state of equilibrium until the PBL reaches its maximum depth in the late afternoon. After sunset, the rapid radiative heat losses occur at the ground so that a second temperature inversion starts to grow near the bottom surface. Although many studies focus on the sensitivity of the structure of the PBL simulation to the PBL parameterization, little attention has been paid to the land surface processes＇ contribution to the development of the PBL, especially the wind field in surface layer. Two planetary boundary layer parameterizations and 3 land surface model （LSM） in WRF model are used to simulate the PBL structures in Beijing area during July 1-4, 2004. The diurnal cycles of surface winds and temperatures and PBL height are analyzed, which shows the temperature and wind fields in the surface layer are sensitive to both the PBL parameterization and the land surface process. The simulations show MYJ scheme gives the more reasonable results than YSU. Noah land surface model considers the soil moisture variation in addition to soil temperature, as the result, the sensitivity of the temperature and wind in surface layer to the PBL scheme becomes strong as the rain appears when use Noah LSM. Noah LSM can produce the heat island phenomenon because it couples a single layer urban canopy model. As a new LSM implement in WRF, RUC cannot describe the variation of the PBL very well. All results of the PBL schemes and land surface models simulated wind speeds in surface layer are much stronger than observations in urban area due to insufficient consideration of the urban building effects. Not only the urban area

关 键 词：WRF模式 边界层参数化 陆面过程 城市边界层 

分 类 号：P433[天文地球—大气科学及气象学]