干旱区生态环境知识资源中心

In this study, land surface energy balance in the oasis-desert ecotone of the northern piedmont of the East Tianshan Mountains, Xinjiang, China was calculated using meteorological data from a Bowen ratio system, in conjunction with modified Bowen ratio method. The daily variation in land surface energy balance was then investigated, along with energy partitioning under different weather conditions. The four weather conditions including sunny day, overcast day, rainy day and average condition. Finally, based on the analysis of relationship between land surface energy and land surface temperature, prediction models for land surface temperature were constructed and validated. The results show that the splendens grassland soil has a cache energy function. Latent heat (LE) plays a dominant role in the energy budget of the oasis-desert zone for all weather conditions, which is inconsistent with some previous studies on other arid areas. The average value of LE/Rn (59%) of this zone is between those of the desert and of the oasis due to the transitional thermal-hydrologic property of the land surfaces and the local circulation. The variations of energy partitioning during the daytime are the same among the different weather conditions, while these curves fluctuate continuously at night, especially before sunrise and after sunset. Except for H, the correlations between each energy component and the surface temperature for different conditions are ordered as follows: clear days > average values > overcast days > rainy days. The same rule is also found in the response intensities (regression coefficients) of the land surface temperature to energy change. The established and validated models for land surface temperature suggest that the soil surface layer temperature is mainly influenced by dry heat energy factors (Rn, G, and II) because of not in the summer monsoon zone and coarser soil particle, rather than the hygrothermal energy factor (LE).