大气科学2013，Vol.37Issue(1)：113-123,11.DOI:10.3878/j.issn.1006-9895.2012.12004
黄土高原复杂地形受中尺度运动影响的稳定边界层湍流特征
Turbulence Influenced by Mesoscale Motions in the Stable Boundary Layer over Complex Terrain of the Loess Plateau
摘要
Abstract
Turbulent characteristics in the stable boundary layer are evaluated by using data collected by the eddy covariance approach at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL). The influence of mesoscale motions in the averaging time is the chief reason for the large scattering of turbulent fluxes obtained by using the eddy covariance technique. The time interval to define the turbulence ranges from several tens of seconds to several minutes. The multiresolution cospectra of the heat flux reveal a gap scale from 112.4 s to 449.9 s for strong stability when gradient Richardson number (Ri) is greater than 0.3. The motions at averaging time scales greater than the gap scale lead to large random heat flux errors and may even change the sign of heat flux cospectra. The gap scale for momentum flux occurs between 112.4 s and 224.9 s. In a weak wind regime in which the submeso velocity scale is greater than the mean flow, standard deviation of vertical velocity depends systematically on the submeso velocity scale and increases with increasing submeso velocity scale at an average rate of approximately 0.1. The standard deviation of vertical velocity correlates well with the generalized velocity scale, and approaches to zero with the generalized velocity scale vanishing. The standard deviations of w, u, and v normalized by friction velocity equal 1.35, 2.54, and 2.21 respectively. Analysis of turbulent kinetic energy reveals that persistent turbulence exists even under condition of Ri> 0.3. Stationarity time based on turbulent kinetic energy changes with stability ranged from 133.5 s to 856.2 s during December 7-11,2008.关键词
稳定边界层/涡动相关/中尺度运动/湍流谱Key words
Sable boundary layer/ Eddy covariance/ Mesoscale motion/ Friction velocity分类
天文与地球科学引用本文复制引用
梁捷宁,张镭,鲍婧,赵世强,黄建平,张武..黄土高原复杂地形受中尺度运动影响的稳定边界层湍流特征[J].大气科学,2013,37(1):113-123,11.基金项目
国家自然科学基金项目41075104,国家重大科学研究计划2012CB955302 （）
