The attenuation of photosynthetically active radiation in the atmosphere over Northern China
光合有效辐射在大气中的衰减

Integrated observations were made of solar radiation and meteorological parameters at 4 stations in North China from September 2004 to October 2006,and the variation of photosynthetically active radiation (PAR) and global radiation (Q) were obtained.Both PAR/Q and PAR were evidently influenced by water vapor and scattering factors.An empirical model of hourly PAR under actual sky conditions was established based on the point of view of energy,and good calculated results were gained.The water vapor factor pl...