Abstract: Based on observational data of ultraviolet radiation,daylight illumination and meteorological parameters during tobacco field growth period (FGP, May to August) from 2008 to 2010 in Yuxi, authors analyzed the relationship between UV radiation intensity and meteorological parameters by using regression method and selected the illumination and cloud cover amount to simulate the ultraviolet radiation intensity. The results showed that the average values of UV intensity during FGP at the same station had no significant difference between different years.Meanwhile,the average values of UV intensity were influenced by the meteorological factors.And the dominant influencing factor was proved to be the cloudage.The daylight illumination and cloudage were best correlated with UV intensity. Authors also investigated the ratio of UV intensity to the daylight illumination, and found that the ratio was not constant but quite stable, UV intensity decreased with the increase of cloudage. The regression model was convenient to calculate ultraviolet intensity only because it only need two input variables i.e.illumination and cloudage.

Key words: Tobacco, Field growth period, Ultraviolet radiation, Meteorological factor