黄土高原半干旱草地近地层湍流温湿特征及总体输送系数  

Characteristics of Turbulence Transfer in Surface Layer over Semi-Arid Grassland in Loess Plateau in Summer

作　　者：岳平[1,2] 张强[1] 赵文[1,3] 王胜[1] 史晋森[3] 王若安[1] 

机构地区：[1]中国气象局兰州干旱气象研究所/甘肃省干旱气候变化与减灾重点实验室/中国气象局干旱气候变化与减灾重点开放实验室,兰州730020 [2]张掖国家气候观象台,张掖734000 [3]兰州大学大气科学学院,兰州730000

出　　处：《高原气象》2015年第1期21-29,共9页Plateau Meteorology

基　　金：国家重点基础研究发展计划(2013CB430206;2012CB955304);国家自然科学基金项目(41075008;40830957;41175011);中国博士后特别资助基金(2013T60901);中国博士后基金(20110490854);中国气象局干旱气象科研基金(IAM201408);甘肃省气象局"十人计划"

摘　　要：利用兰州大学半干旱气候与环境观测站(简称SACOL站)2008年夏季晴天近地层湍流观测资料,分析了SACOL站近地层湍流温、湿统计特征,确定了大气动力学和热力学粗糙度长度,讨论了总体输送系数随大气稳定度的变化规律。结果表明,大气层结不稳定条件下,无量纲温度和比湿脉动方差与稳定度Z/L之间均满足-1/3次规律;大气层结稳定条件下,温湿脉动方差总体趋势是随大气稳定度增加而减小。水汽通量全天大于零,最大值为0.063 g·m-2·s-1,地表日平均蒸发量为1.9 mm。中性条件下,黄土高原半干旱草地动力学粗糙度长度为6.6×10-3m,热力学粗糙度为1.85×10-5m。大气层结不稳定条件下,CD平均值为4.4×10-3,CH平均值为3.9×10-3;中性条件下,CD和CH平均值分别为4.2×10-3和2.8×10-3;层结稳定条件下,CD平均值为3.1×10-3,CH平均值为2.1×10-3,表明总体输送系数随稳定度的增大而减小。The turbulent data observed at the Semi-Arid Climate and Environment Observatory of Lanzhou University( SACOL) in sunny days over semi-arid grassland in the Loess Plateau from June to August 2008 w ere used to investigate the relation betw een dimensionless turbulent wind variance and stability parameter( Z / L) and the turbulence transfer characteristics. The results show s that the wind components spectra computed by the Fast Fourier technique w ere satisfactory the Kolmogorov similarity hypothesis. The average actual evapotranspiration in sunny days is 1. 9 mm w hen the daily mean soil humidity at 5 cm is about 15%,the moisture flux is greater than zero and a maximum of 0. 063 g · m- 2·s- 1. Under the convective condition,the stability parameters( Z/L) dependence on the variance of dimensionless temperature and specific humidity can be fit to a power law with an index of- 1 /3. The dynamical and thermal-dynamical roughness length over Loess Plateau semi-arid grassland is 6. 6 × 10- 3m and 1. 85 × 10- 5m. The bulk transfer coefficient CDand CHare 4. 4 × 10- 3and 3. 9 ×10- 3under unstable stratification; CDand CHare 4. 2 × 10- 3and 2. 8 × 10- 3under the near neutral stratified condition; CDand CHare 3. 1 × 10- 3and 2. 1 × 10- 3under stable stratification.

关 键 词：黄土高原 湍流特征 粗糙度长度 总体输送系数 

分 类 号：P404[天文地球—大气科学及气象学]