Abstract: Based on the observational data four times a day at four meteorological stations in Bengbu from 1970 to 2015,including relative humidity,visibility,weather record,etc,and using an objective method to identify haze events,the climatic time series of haze days in recent 64 years were reconstructed and its spatiotemporal characteristics and relationship with criteria meteorological parameters were analyzed.The results showed that haze days series reconstructed from the daily mean value method can reasonably represent the long-term characteristics of haze events,which is well consistent with the haze days series obtained from the weather records,showing a significant correlation between them.The haze days number varied largely at different meteorological stations in Bengbu from 1970 to 2015,with larger value in south and smaller value in north.The largest total haze days number occurs at Bengbu station.The number of haze days in Bengbu is large in autumn and winter and small in summer,and it exhibits obvious decadal variation in the past 46 years.The number of haze days increases generally.After 2000,its increasing rate reaches 4.8 d·a^-1.However,it decreases slightly in the period from the late 1980s to the early 1990s.The favorable meteorological conditions for the formation and development of haze events in Bengbu include the easterly wind in the near surface layer,high relative humidity,shallow mixing layer height,and the existence of temperature inversion.The relationship between haze days number and air temperature and pressure is not significant.

Key words: Haze days, Data reconstruction, Meteorological parameters, Climate tendency, Correlation analysis