张掖地区的光合有效辐射特征

光合有效辐射(PAR)是植物进行光合作用的重要能量来源。本文利用HEIFE期间在临泽(FOP)和张掖(BOP)取得的太阳分光辐射资料，分析研究了张掖地区的光合有效辐射。结果表明：张掖地区晴天PAR在太阳总辐射中所占的比例在0.419-0.426之间。季节变化不明显；多云天气条件下比值大于晴天，且有较明显的季节变化，夏季大。冬季小。文中还根据实际观测资料拟合得到了张掖地区PAR的经验公式，据此估算和讨论了张掖地区PAR的分布情况．

CHARACTERISTICS OF THE PHOTOSYNTHETICALLY ACTIVE RADIATION OVER ZHANGYE REGION

Photosynthetically Active Radiation( PAR) is an important energy source of photosynthesis for the green plants. In this paper, characteristics of the photosynthetically active radiation over Zhangye region are analysed and studied by using the data of solar spectral radiation during HEIFE FOP and BOP at Linze and Zhangye station, respectively. The results show: in clear case the ratio of PAR to global radiation is a range from 0.419 to 0.426 over Zhangye region and the seasonal variation is not obvious. In cloudy case, the ratio of PAR to global radiation is larger than that in the clear case, their seasonal variation is obvious, and the ratio is large in summer and small in winter. In addition, the empirical formula to calculate the PAR over Zhangye region is fitted base on the observed data and the distribution of PAR over Zhangye region is also discussed in this paper.