用涡动相关技术观测长白山阔叶红松林蒸散特征

该文利用开路涡动相关系统测定了长白山阔叶红松林2003年蒸散量(潜热通量LE)，并分析了其日、季变化特征.结果表明，该观测系统的能量平衡闭合度为86.5%，处于国际同类观测闭合度范围(60%～90%)的中上水平，说明长白山涡动相关法观测数据可信度较高.潜热通量与净辐射(Rn)呈二次曲线关系，与气温(Ta)呈指数关系，模拟出的LE日总量与Rn、Ta经验关系式，可对LE缺值进行插补.森林蒸散量日变化特点是白天高于夜间，中午最高，夜间潜热通量和显热通量(H)有低估的现象；季节变化特点是7、8月份蒸散量最高，冬季较低，且蒸散量在净辐射中所占的比例为生长季明显高于非生长季.该森林蒸散年总量为1 126.99 MJ/m2，相当于450.8 mm降水量，占年总降水量(538.4 mm)的83.7%. 关键词:森林蒸散, 能量平衡, 涡动相关法, 阔叶红松林 

Measurement of evapotranspiration above broadleaved_Korean pine forests in the Changbaishan Mountains with eddy covariance technique

Based on the measurement of latent evapotranspiration (LE) and sensible heat flux by open-path eddy covariance (OPEC) system, the authors analyzed diurnal and seasonal variations of forest evapotranspiration in the broadleaved_Korean pine forests in Changbai Mountain in 2003. The results showed that the energy balance closure was 86.5%. This suggested that the latent heat flux and sensible heat flux measured by OPEC system at the forest site were reasonable according to the internationally reported energy closure range (60%-90%). The LE gaps were filled by multiple polynomial regressions on the net radiation (R_n) and air temperature (T_a). Forest evapotranspiration was higher in the daytime than that at night, with the highest value occurring at noon. The maximum of monthly forest evapotranspiration appeared in July and August, and the minimum appeared in winter months. The ratio of evapotranspiration to net radiation in the growing season was evidently higher than that in the non-growing season. The annual evapotranspiration amounted to 1 126.99 MJ/m2 (450.8 mm of rainfall), accounting for 83.7% of the annual rainfall (538.4 mm).