Abstract: Integrated measurement on the solar radiation (including photosynthetically active radiation (QPAR),visible radiation (QVIS),global radiation (Q),and etc.),meteorological parameters at Luancheng were made four times during July 19,2005 to September 31,2006. The variation characteristics of QPAR and QVIS were obtained. The results showed that the ratios of hourly sum of QPAR to Q,QVIS to Q,QPAR to QVIS were relatively stable,averaging at 1.94 mol MJ-1,0.39,4.95 mol MJ-1,respectively. These ratios displayed obvious diurnal,daily and seasonal variations,and were influenced by water vapor,aerosol,clouds and etc. The empirical formulas were built up for calculating hourly sums of QPAR and QVIS and their relationship under actual sky conditions. The calculated QPAR and QVIS were in accordance with the observed data,and their relative biases were 14.4% and 13.9%,respectively,when water vapor and scattering factor were considered. In the actual condition with only water vapor factor considered,their relative biases were 15.2% and 14.2%,respectively. Water vapor played a very important role for the estimation of hourly sums of QPAR and QVIS by using the ratio of QPAR/Q,QVIS/Q. Aerosol's role is less important,but it should also be considered.

Key words: Solar radiation, Solar radiation, Photosynthetically active radiation, Visible radiation, Cloud, Water vapor, Scattering factor