Abstract: Based on the daily four times' records of temperature and daily maximum and minimum temperature in Zhengzhou meteorological station from 2005 to 2007,the daily variation of air temperature was by the sine-exponential model,the Tk method and the piecewise linear model which proposed in this paper.The simulated results showed that the piecewise linear model performed better than the other two methods with a ME(Model Efficiency)by 0.99 and a less RMSE(Root Mean Square Error).Under different weather conditions,the simulated precision for the sine-exponential model and the Tk method was best in cloudy days,followed by clear days and overcast days.However,the simulated precision for the piecewise linear model was best in overcast days,followed by cloudy days and clear days.For all of three methods,the performance in daytime was always better than that at night.

Key words: Air temperature, Air temperature, Daily variation, Sine-exponential model, Piecewise linear model, Tk method