【摘要】 分析了南亚热带针阔混交林各外向辐射通量:上行短波辐射(RSu)、上行长波辐射(RLu)和上行总辐射(RTu)在不同时间尺度上的分布特征、相互关系以及影响因素.研究表明:中小时间尺度(≤1月)上,变异系数的大小顺序均为:RLu<RTu RSu;RSu在雨季和旱季的日均变化均呈规则的正态单峰曲线,而RLu呈波浪形,RTu则呈不规则的单峰曲线;RTu占全年进入生态系统总辐射能量的82.93%,而RLu占RTu的97.36%,分别说明了外向辐射在系统辐射平衡中,以及RLu在系统外向辐射中的重要影响;全年日均反射率η为8.30%,月均反射率(y)与降雨量(x)的回归方程为:y=-0.385lnx+9.3376,R2=0.6762,相关性达显著水平.在日尺度,影响η的主要因素可能是下垫面湿润程度的不同;对RLu与各层次温度进行的多种函数拟合表明,第2层(9 m)气温最能代表该系统的真实表面温度",而在应用Stefan-Boltzmann方程时必须根据实际情况进行校正,否则会产生较大的误差;在较大时间尺度(1月)上,净辐射(Rn)与RTu和RLu相关性较好,Rn与RSu的相关性未达显著水平.而在较小时间尺度(≤1 d)上,Rn与RSu相关性较好,且时间尺度越小,Rn与RSu的相关性越好,这充分说明了以往辐射平衡研究中往往忽略的尺度效应的影响.更多还原

【Abstract】 The characters of outside radiation fluxes of coniferous and broad-leaved mixed forest were studied, including the distribution of upwelling shortwave radiation(RSu),upwelling longwave radiation(RLu),upwelling total radiation(RTu),and the relationship between these components and the environmental factors.The major results were as follows: At middle and small temporal scales(≤1 month),the coefficient of variation(CV) of outside radiations fluxes were RLu < RTu RSu.In wet and dry season,the average diurnal processes of RSu presented normal peak type curves,the processes of RLu presented undee curve,however the RTu presented anomalous peak type curves.Among the total energy input to the ecosystem,RTu was the largest fraction(82.93%),which indicated that outside radiation fluxes were very important to the energy balance of ecosystem.In the total upside energy,RLu was the largest fraction(97.36%),proving that RLu was more important than RSu which was disagreed with the usually considering.The average daily reflect coefficient(η) was 8.3%.The regression equation between monthly η(y) and precipitation x was: y=-0.385lnx+9.3376,R2=0.6762.The main factor which influences daily η might be precipitation.The regression analysed between RLu and temperatures,including air temperatures of different height and canopy infrared temperature of the forest ecosystem,indicated that the second layer air temperature(9 m high) had the most closely related to the true surface temperature.The being using Stefan-Boltzmann equation must be revised.In a longer temporal-scale(≥1 month),for example,there existed very obvious correlation between monthly Rn and monthly RLu,monthly Rn and monthly RTu.However,the correlation between Rn and RSu,was not significant.In a shorter temporal-scale(≤1 d),this correlation is significant,it seems that the shorter the temporal-scale is,the better the correlation between Rn and RSu is,indicating that the influence of temporal-scale can’t be ignored in research of radiation balance.更多还原