Abstract: The 56 weather stations in Liaoning province were sifting repeatedly according to some rules such as the distance between weather stations and so on. The characteristics of urban heat island (UHI) in four cities (Dalian, Dandong, Jinzhou and Tieling) where the number of weather stations was different with and without sifting weather stations were analyzed using a temperature difference method. The results indicate that for the annual UHI character, the UHI intensity is different in four cities from 1980 to 2011 with and without sifting weather stations, while both trends are similar. Among four cities, the UHI intensity is the highest in Tieling weather sifting weather stations or not, and their average values are 1.53 ℃ and 1.85 ℃; their ranges are 1.17—1.80 ℃ and 1.55—2.15 ℃; their amplitudes of fluctuation are 0.63 ℃ and 0.60 ℃, respectively. The years that the UHI intensity grade changes with and without sifting weather stations account for 25% in Tieling, and it is the highest among four cities. In general, the effect of sifting weather stations on the annual UHI intensity is weak. For the monthly UHI character, the variation is significant in Dalian with and without sifting weather stations from 1980 to 2011, while it is not significant in other three cities, especially in Jinzhou. The variation of monthly UHI intensity grade is obvious in each month, and the maximum appears in October and November in Dandong. The years that the UHI intensity grade changes with and without sifting weather stations account for 90.6%. In general, the effect of sifting stations on the monthly UHI intensity is obvious.

Key words: Weather station, Sifting weather station, Urban heat island intensity, Urban heat island intensity grade