摘要:
该文分析了南亚热带针阔混交林各辐射分量:下行短波辐射(RSd)、上行短波辐射(RSu)、下行长波辐射(RLd)和上行长波辐射(RLu)在不同时间尺度上的分布特征和相互关系.结果表明:在日尺度上,各辐射分量日总量的大小顺序为:RLu(36.34 MJ/(m2.d))＞RLd(32.43 MJ/(m2.d))≫RSd(12.46 MJ/(m2.d))＞RSu(0.98 MJ/(m2.d)),长波辐射的变异系数(CV)远小于短波辐射,而波长相同时上行辐射的CV小于下行辐射.除RLd外,其余3种辐射的月均通量呈单峰形变化.RSd与RSu在不同季节的日变化均呈规则的单峰曲线,而RLd和RLu的日均变化则大致呈波浪形.全年系统辐射支出中RLu为80.7%,RSu仅占2.2%,RLu在辐射平衡中的作用远超过以往强调最多的RSu.日尺度上,2003年反射率η的平均值为8.3%.在不同时间尺度上影响η的主要因素是不同的.与旱季相比,雨季两种长波辐射的相关性高,数值也更接近.在较大时间尺度(1个月)上,净辐射(Rn)与RLu相关性最好,而在较小的时间尺度(≤1 d)上,Rn与RSd相关性最好,故在考察辐射通量间相互关系时,应充分注意尺度效应的影响.
Abstract:
The distribution characteristics and relationship of radiation flux,including downwelling shortwave radiation(RSd),upwelling shortwave radiation (RSu),downwelling longwave radiation(RLd) and upwelling longwave radiation(RLu) of coniferous and broadleaved mixed forests in low subtropical China,were analyzed.The major results were as followings: the average daily radiation flux was RLu(36.34 MJ/(m2·d))＞RLd(32.43 MJ/(m2·d))≫RSd(12.46 MJ/(m2·d)) ＞ RSu(0.98 MJ/(m2·d)).The variation coefficient(CV) of long wave radiation flux was obviously less than that of shortwave radiation flux.When the waves of radiation were the same,the CV of upwelling was less than that of the downwelling.All of the monthly gross radiation flux fluctuated in single apex in a year,except RLd.The average diurnal processes of RSd and RSu presented peak type curves,however the processes of RLd and RLu presented wave curves.In the output of radiation flux in 2003,RLu was the largest(80.7%) and the percentage of RSu was only 2.2%.These indicated that RLu was more important than RSu,which was considered as the most important part of output radiation.The average daily short radiation reflected that coefficient(η) was 8.3%.The dominant factors of η in different temporal scales were varied.In longer temporal-scales as monthly, there existed good correlation between Rn and RLu,while there existed good correlation between Rn and RSd in short temporal-scales(≤1 d).It seemed that the shorter the temporal-scale was,the better the correlation was.It indicates that it is very important to emphasize the temporal-scale when researching the relationship of the radiation flux.
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