摘要
本文利用1986年夏季青藏高原试验(TIPMEX—86)期间获取的资料,计算分析了该年6月和7月拉萨和那曲近地层摩擦速度u_*、特征温度θ_*、Monin-Obukhov长度L及理查逊数R_i在不同大气层结及不同高度的分布特征。分析结果表明:不同大气层结下,湍流运动形式是不同的,湍流热力场的变化远远大于湍流动力场。就空间变化而言,θ_*随高度变化较大,而u_*的变化较小。对大气层结而言,在稳定条件下,u_*、θ_*随高度变化较大;在不稳定条件下,θ_*、u_*随高度变化较小。 在不稳定层结相近的状况下,高原开阔草地上的各种湍流参数,接近或大于北京城郊非均匀地形的数值,而在很稳定的层结下,则高原的参数值小于北京。
This paper is to describe the distribution features of turbulent parameters,friction velocityu_*, characteristics temperature θ_* and Monin — Obukhov length L,and Richardson numberR_i atthe various levels with different stratified conditions in the surface layer at Lhasa and Naqu sitesduring June and July 1986 by using the data from the Tibetan Plateau Meteorological Experi-ment 1986 (TIPMEX — 86). The results show that there are a variety of turbulent motion formsunder various conditions of the stratification,and the adjustment of thermal process is faster thanthat of dynamical process. It has also been found that under stable conditions, the change of u_* orθ_* with height respectively is larger than that under unstable conditions. The turbulent parametervalues for L<0 in the plateau are near to or larger than those in Beijing suburb. But for L>0,the former is smaller than the later.
