Abstract:

The research based on the solar radiation observation data of the Shouxian National Climate Observatory (32°30.83' N, 116°46.47' E) of the whole 2008 year. The research analyzed the features of the annual, seasonal and daily variation of PAR, and the ratio of the Solar short-wave radiation (Rs). The annual amount of PAR of the area was 1970.8 MJ/m2. The average daily volume of spring, summer, autumn and winter respectively: 6.83 MJ/m2, 6.58 MJ/m2, 4.28 MJ/m2, 3.80 MJ/m2. The monthly average PAR/Rs value between 0.37 and 0.43, the maximum value was 0.43 in summer, the minimum value was 0.37 in winter, and annual average value was 0.40. Found the changes in PAR in sunny and cloudy days was significantly different, PAR/Rs values cloudy day bigger than the sunny day, PAR/Rs value was 0.42 in the typical cloudy day over the year, whereas PAR/Rs value was 0.39 in the typical sunny day. Clouds, water vapor, solar radiation and atmospheric turbidity had effects on PAR / Rs.