油松冠层辐射特征的研究

Characteristics of Solar Radiation and Its Distribution above the Canopy of the Pinus tabulaeformis

为深入了解油松冠层的辐射平衡特征,采用辐射表定点观测方法,对油松冠层太阳辐射的时空动态进行了系统性测定。结果表明:①晴朗天气、多云条件下的油松冠层太阳总辐射和试验区晴天太阳总辐射等3种不同测量环境条件下总辐射的差值较大,最大值分别为799 W/m2,499 W/m2和861 W/m2。②油松冠层的净辐射具有与总辐射相似的日变化规律,且两者之间具有很好的线性关系,净辐射率的日变化趋势为中午高,早、晚低;晴天日间净辐射率较稳定,多云天气起伏较大。③太阳在油松冠层的不同位置辐射会出现明显的垂直分布趋势,随着高度的下降,太阳总辐射、净辐射随之减弱。

In order to further know the characteristics of the radiation balance of the Pinus tabulaeformis canopy, the changes in the temporal and spatial characteristics of radiation within the Pinus tabu- laeformis canopy was tested systematically using fixed-point observation method by radiometer. The results as follows. First, the total radiation is quite different in three kinds of testing environments, the solar total radiation of the Pinus tabulaeformis canopy in sunny days, in cloudy days and the solar total radiation in testing area in sunny days, the maximums were799W/m^2, 499W/m^2 and 861W/m^2 respectively. Second, the net radiation of the Pinus tabulaeformis canopy and the total radiation have the similar law of daily variations. Besides, they two have linear relationship. Daily variations of distributing ratio of net radiation showed a tendency of higher values in the day time and lower in the early morning and in the afternoon. Ratio of net radiation is relatively stable in the daytime in sunny clays and changeable in cloudy days. Third, the solar radiation showed the vertical distribution tendency in different positions in the Pinus tabulaeformis canopy. The solar total radiation and the net radiation decreased with the height lowering.