数值模拟的优缺点优点

观测与模拟技术 回顾气象学发展的历史 古代气象学 现代气象学 气象学是建立在观测基础之上的一门科学 观测的重要性 了解大气 常规观测：地面观测、 高空观测 非常规观测：雷达、卫星观测 验证预测 观测与观测技术 大量有关边界层的结构极其演化、规律的知识来自观测 观测大致分为2类 a) IN SITU (in the position of) b) REMOTE SENSING 根据探测原理：主动式，被动式 a) IN SITU (in the position of) examples include: surface weather stations portable mesonet stations instrumented towers balloon soundings aircraft tetroons tethersondes b) REMOTE SENSING examples include: Doppler radars (like the WSR-88D) profilers RASS (radio acoustic sounding system) sodars lidars photogrammetry Surface Weather Stations? 观测项目 winds pressure temperature moisture LW and SW radiation precip amount and type cloud base aerosol concentrations trace gas concentrations and the list goes on .... Portable Mesonet Stations Instrumented Towers This will allow you to measure the vertical profiles of variables of interest. balloon soundings Aircraft Tetroons Tethersondes Tethersondes are nothing more than a sophisticated kite. Essentially, the balloon rises to some altitude.? Met sensors are placed at regular intervals on the tether. b) REMOTE SENSING examples include: Doppler radars (like the WSR-88D) profilers RASS (radio acoustic sounding system) sodars lidars photogrammetry Weather Doppler Radars (WSR-88Ds) 雷达拼图 Doppler radar工作原理 雷达图象(1) 雷达图象(2) profilers Wind Profilers are similar to Doppler radars Wind profilers continuously point upward. profilers观测的风垂直分布 RASS (The Radio Acoustic Sounding System) It is often collocated with profilers.? They collect vertical profiles of virtual potential temperature by measuring changes in sound wave propagation RASS探测的温度分布 Sodars?(Sonic detection and ranging) Lidar Lidar图象 Photogrammetry 卫星图片 模拟与模拟技术 大气边界层现象的不可重复性与复杂性 模拟大致分为2类 a) 物理模拟 b) 数值模拟 a) 物理模拟 实验室里进行(实验箱或风洞) 实物模型按比例缩小 有时用水代替空气 层结化处理 …… 物理模拟的优缺点 优点： 直观、形象； 对于复杂的小尺度现象很有使用价值 缺点： 流体层化(密度层化、稳定层化)比较困难； 很难达到真实大气的状态(如高雷诺数，科氏效应等)，因此不适用于较大尺度 b) 数值模拟 物理模拟所碰到的问题理论上在数值模拟中几乎都可以得到解决； 在大气科学研究