Statistical Analysis on Relationship Between Soil Surface Temperature and Air Temperature

Based on the data of daily mean temperature from 1955 to 1999 and data of daily mean soil surface temperature from 1981 to 1998 in the Haidian District of Beijing City, the soil surface temperature prediction model based air temperature was established, and yearly variations of the temperature difference between air and soil surface temperature were studied, by using agro-climatological and agro-meteorological statistical principals and methods.The soil surface temperature was higher than the air temperature in the summer half year and it was lower than that in the winter half year.The average temperature difference between air and soil surface was 2.0℃ during growing season of crops (from March to October); The yearly average temperature difference between air and soil surface was 0.9℃, and the maximum and minimum were 4.9℃ (in the second ten days of June) and -2.7℃ (in the third ten days of December) respectively.The occurrence dates of the maximum and minimum temperature difference were consistent with the maximum and minimum radiation.The relatively error of the daily mean soil surface temperature estimated for 1999 was lower than 2.9%.