Abstract: Based on the monthly temperature of 0-20cm soil and air temperature of 16 stations in southeast Guizhou province from 1961 to 2010, the series of temperature difference from soil to air (referred to as Ts Ta) in four seasons were calculated respectively. The spatial distribution and changing tendency was analyzed by using of orthogonal function decomposition (EOF), empirical mode decomposition (EMD) and Mann-Kendall methods. The results showed that the value of Ts Ta was positive in every season, but there was big difference in spatial and temporal distributions among seasons, in which highest value occurred in winter and lowest value in spring. The distribution of the highest value center was different each quarter as affected by large scale climate anomalies. The first component (IMF1) was important component in oscillation mode of Ts Ta in each season. Ts Ta in spring and autumn showed obvious increase (P＜0.05) in last 50 years in southeast Guizhou, but not obviously in winter and summer. The mutation point of Ts Ta in spring and autumn occurred in 1970s, and that in winter and summer occurred in 1990s, which indicated that the change of Ts Ta had obvious stage and regional differences in every season.

Key words: Southeast Guizhou, Soil air temperature difference (Ts Ta), EOF analysis, EMD analysis