森林近地层大气湍流特性观测分析

利用长白山森林生态系统定位研究站观测资料,及2003年8月和9月涡旋相关资料,分析和比较了该地区近地层包括风速、风向、大气稳定度在内的平均场特征,以及湍流强度、无量纲化风脉动方差相似性和地表通量变化特征。结果表明:(1)8月和9月稳定度都基本集中在0附近;(2)风速2 m·s-1的环境中,湍流发展最为旺盛,随着风速的增大湍流强度先迅速减小,当风速增大到3 m·s-1后,湍流强度偏离0值变大了一些,再继续增大到一定风速大小以后,湍流强度基本不随风速变化;(3)无量纲化三维风脉动方差符合Monin-Obukhov相似理论的"1/3"定律,其最佳通用相似函数在稳定和不稳定条件下都可以拟合得到;(4)地表通量均表现出明显的日变化特征,8月以潜热为主,感热较小;9月仍以潜热为主,但是相比8月明显偏小,感热变化不大。

Observational Analysis on Turbulent Characteristics of the Atmospheric Surface Layer Above Forest

The measurement and observation for this study were carried out by using a three-dimensional （u,v,w）sonic anemometer （IAP-SA 485 ）at the Forest Ecosystem Opened Research Station of Changbaishan Mountains.Some micrometeorological characteris-tics of wind speed,wind direction,atmospheric stability,and turbulent intensity,variance similarity,scalar fluxes in the near-sur-face layer were analyzed and compared on the basis of the observational data acquired by using the eddy correlation method in August and September 2003.The main results are as follows：（1）Atmospheric stability in August and September was basically concentrated in the vicinity of 0.（2）Turbulence was very active when wind speed was less than 2 m·s^-1 and decreased rapidly with wind speed in-creasing.When the wind speed reached 3 m·s^-1 ,the turbulence intensity deviated from 0 and got larger,and continued to increase untill a certain wind speed,then turbulence intensity didn’t change with wind speed basically.（3）The normalized variance of three-dimensional wind and z/L satisfied the similarity law under both unstable and stable stratification.Their universal functions also could be fitted according to the“law of 1/3 fractional power”.（4）The diurnal variations of surface fluxes were evident,and latent heat flux was leading in August and September.Latent heat flux in September was significantly less than that in August.Sensible heat flux var-ied little in August and September.