Based on the surface meteorological observation data of Nancheng station from 2003 to 2011

the relative humidity manual and automatic observation records are compared and analyzed

and the monthly relative humidity manual observation values of Nancheng station are close to the automatic observation results

97.25% of the monthly mean relative humidity of manual observation is higher than that of automatic observation. 75.49% of the time-to-time observed relative humidity was higher than that of the automatic observation

and the difference between the time-to-time observed relative humidity and the automatic observation was mainly between-5% and 10%. Based on the observation record of visibility

this paper analyzes the occurrence time of haze

light fog and fog according to the statistics of relative humidity by manual and automatic observation. The results show that the relative humidity system is lower after automatic observation of relative humidity

as a result

the observed records of haze at Nancheng station increased obviously

and the light fog decreased

but the effect on the observed records of fog was not significant.