上海市郊林带附近晴天地表热量平衡特征的分析

Characteristic analysis of surface heat balance of the near-forest in fine winter and summer days in Shanghai suburb

林带附近的热量平衡各分量的变化体现了林带对周围近地大气环境的影响。本文根据上海市郊林带附近温、湿、风梯度及净辐射观测资料,分析了林带附近冬夏晴天热量平衡各分量的特征,结果表明:夏季林带附近的净辐射比非林带小,冬季则比非林带大;林带对风速有减弱作用,林带附近的湍流输送较弱,因而林带附近热量和水汽量输送较小;林带附近有植物蒸腾,蒸散耗热量较大,为热量平衡中主要支出项;土壤热通量变化与近地面地温变化有关;林带附近较大的蒸散耗热和较弱的湍流输送有利于有利林带附近土壤水分的储存,并使周围湿润,但高温或低温时,湿度增加会引起人体不适,在林带规划上要充分考虑以上特点。

The variety of surface heat balance items can reflect influence of the forest band on surface atmosphere environment around the forest band. Based on gradient observation data of temperature, humidity, wind and net radiation near forest band in Shanghai suburb, the characteristic of each item of heat balance in fine winter and summer days was analyzed. The results showed that the net radiation near forest band was smaller than the non- forest band in summer, but it was bigger than the non- forest band in winter, the turbutent heat flux near forest was insignificant since the wind speed could be weaken by forest, transportation quantity of heat and moisture near forest band tend to be less. As for plant transpiration near forest band, it was evapotranspiration heat flux that dominanted item in surface heat balane. In addition, soil heat flux change was related to ground temperature change near surface. The remarkable evapotranspiration heat flux and the feeble turbutent heat flux would benefit for the deposit of soil moisture and wetness. However, increasing the humidity makes people uncomfortable at high and low temperature. So all the characteristics above must be fully considered during city forest programming.