关键词: 太阳辐射, 光合有效辐射, 可见光辐射, 水汽, 散射因子

Abstract: Solar radiation (photosynthetically active radiation (PAR), visible radiation (VIS), global radiation (Q), etc.) and meteorological parameters were determined from September 12, 2004 to October 31, 2006 in Xianghe, Hebei province. The variations of PAR and VIS were analyzed. The results show that the ratios of hourly sums of PAR/Q, VIS/Q, PAR/VIS are relatively stable, and their averages are 2.164, 0.434 and 4.967 mol•MJ-1 from 2004 to 2006. These ratios are of obvious diurnal, daily and seasonal variations, and are influenced by water vapor, aerosol, clouds, etc. The empirical formulas calculating hourly sums of PAR and VIS under weather conditions and conversion formulas between PAR and VIS are established. The calculated PAR and VIS were in good agreement with the measured, and their relative biases are 9.9% and 10.8%, respectively, if water vapor and scattering factor are considered. According to the actual conditions, if water vapor factor is considered simply, the relative biases between the calculated and the observed are 11.1% and 11.8%, respectively. Water vapor factor is important for the transmission and the calculation of PAR and VIS. At the same time, the scattering factors are also important.