摘要
利用中国科学院大气物理研究所大气边界层物理与大气化学国家重点实验室的北京325m气象塔1993年～2003年夏季(7月～9月)的观测资料,统计分析了各年的风速与温度廓线分布特征。统计分析结果表明,随着城市化的发展,相对风速有逐年减小的趋势,并且越靠近地面,相对风速的减小越明显,这反映了城市建筑对近地面层空气流动的摩擦作用。对风速廓线进行线性拟合得到风速随高度的垂直递增率,发现无论是100m以下的近地面层还是较高层,风速的垂直递增率都随城市化发展存在逐年增大的趋势,表明粗糙下垫面的影响已经向高层扩展。根据温度廓线计算了各年的温度垂直递减率,发现其有增大的趋势,这表明城市化发展对边界层热力结构同样有显著影响。本文还依据统计整理得到的近中性层结下的风速廓线资料,利用莫宁-奥布霍夫相似理论计算了下垫面的空气动力学参数,结果表明,地表粗糙度、零平面位移随着城市化发展皆有明显增加的趋势。同时,分析了各空气动力学参数与平均风速及无量纲风速的关系。其中,摩擦速度和平均风速二者基本成正相关,且摩擦速度随平均风速的增大而增大的趋势越发明显。本文研究结果对研究城市化发展对区域大气边界层结构、气候和环境影响有参考意义,可为城市大气边界层模式和区域气候模式提供参数化依据。
The situation of wind speed and temperature is analyzed by utilizing the observational meteorology data from the Beijing 325-m meteorology tower of the Institute of Atmospheric Physic of Chinese Academy of Sciences. The analysis indicates that the relative wind speed is in decrease, and at lower levels the decrease is even more ap- parent The vertical increasing rate of wind speed, calculated by making a linear fitting of the wind speed profile, shows an increase trend at both the lower levels under 100 m and the levels above. The vertical decreasing rate of temperature, which is generated from the temperature profile, is in increase over those years, indicating the urbani- zation influence on the thermodynamic structure of boundary layer. By utilizing the wind speed profile in a nearly neutral stratification, the aerodynamic parameters of the boundary layer are calculated based on the Monin-Obukhov similarity theory, showing an apparent increasing trend of the roughness length and zero-plane displacement. The a- nalysis also shows that the relationship between friction wind speed and average wind speed is linear, and the in- creasing trend of friction wind speed with the average wind speed increases becomes more and more apparent. The results of this paper can be referenced by the researches of urbanization and urban environment, and can also provide potential parameterization for the boundary layer model as well as the regional climate model.
出处
《大气科学》
CSCD
北大核心
2009年第4期859-867,共9页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40875004
中国科学院大气物理研究所大气边界层物理与大气化学国家重点实验室开放课题LAPC-KF-2009-04
北京大学校长基金项目
关键词
城市化进程
边界层结构
下垫面性质
廓线
空气动力学参数
urbanization, structure of boundary layer, characteristics of the underlying layer, profile, aerodynamic parameter
