中性温度层结时森林郁闭度与林冠上风速廓线的关系

The Relationship Between Canopy Density of Forest and Wind Speed Profile Under Neutral Stratification

该文利用风洞实验及野外实测资料，用逼近方法求出中性温度层结时不同郁闭度林分林冠以上风速廓线特征．结果表明，风速廓线参数（零平面位移ｄ、林冠表面粗糙度Ｚ０、动力速度Ｕ）随郁闭度Ｃ的变化而改变，ｄ随Ｃ的增大而增大，二者关系可由对数函数表示：ｄ＝（Ｈ／ａ）ｌｎ（Ｃ／Ｃ０）．Ｚ０和Ｕ的变化特征比较相似，在Ｃ＝０２附近有最大值，Ｃ再增大或减小。

Under neutral stratification the parameters of wind speed profile (zero plane displacement d,roughness length Z 0 and friction velocity U *) above forest with different canopy density C are calculated by approximating method. The results show that d increases with the increase of C,and the relation of them fits the logarithmic function d=(H/a)ln(C/C 0). The variation trends of Z 0 and U * versus C are similar, and have the maximum near C=0.2,when C depart from this point, Z 0 and U * decrease gradually.