Abstract: Based on the observational data from 13 surface meteorological stations in Tianjin from 2005 to 2016,the spatial distribution of haze-fog events in Tianjin was analyzed and its effect on the solar radiation was quantitatively studied using observational data of solar radiation at Xiqing station.The results showed that haze-fog events in Tianjin occur more frequently in north than in south,with a greater number of haze-fog day observed in Baodi and Jizhou and a smaller number of haze-fog day observed in the southern area of Binhai New District.The number of haze-fog day in Tianjin increases initially from 2005 and decreases later.Temperature inversion occurs frequently in autumn and winter,and the adverse diffusion conditions result in the frequent occurrence of haze-fog events.Therefore,the prevention and treatment of haze-fog events in autumn and winter are very important.The greatest influence rate of haze-fog events on solar radiation occurs in winter during the recent 12 years.With increasing duration of haze-fog events,the occurrence of haze-fog events in Tianjin decreases in a form of the power function.However,the decline of solar radiation due to haze-fog events in Tianjin becomes stronger.The solar radiation decreased by 57.14% compared with the background solar radiation in a 6-d persistent haze-fog event.The occurrence and persistence of haze-fog events have great effect on the production of facility agriculture and solar power generation in the northern region of China during winter,and some proper strategies should be taken in order to minimize disaster losses.

Key words: Haze-fog event, Solar radiation, Influence rate, Persistent day number