Abstract:

This article had discussed the process and characteristics of energy delivering in the interface of surface and atmospheres in farmland ecosystem through analyzing the soil thermal regime, which would provide the reference to the study of land surface process and atmospheric boundary. Based on the meteorological observation data on 2008, we studied the monthly variable characteristics from surface albedo, soil temperature gradient, and soil heat flux, the relations between soil heat flux and the net radiation. The results showed that: (1) The changes of both temperature gradient and its amplitude were not obvious with the days strengthened. The monthly changes of every layer but 10-20 cm was declined to the minimum value in May and the first ten days of June, and increased to the maximum value in November and the last ten days of next February. (2) With respected to changes on soil heat flux, monthly variation was opposite to the changes of soil temperature gradient. (3) In the months of scales, the climax point of the albedo was shown in January, and changed smaller from March to September among the other period. It declined to the lowest point 0.14 in September. It significantly increased from October to December until maximum 0.66 shown in January. (4) It was not simple linear relationship between net radiation and soil heat flux .The radiation intensity of 1 day was consistent with difference heat flux, and the delaying of soil heat flux was not obvious. When radiation increase, the fitted curve between net radiation and heat flux, R12=0.766 less than R22=0.799 when radiation continuous reduction. The correlation of farmland ecosystem between net radiation and soil heat flux is much higher than that of forest land and is lower than that of grassland and sparse shrubs.