关键词: 民勤, 绿洲, 荒漠化, 辐射特征, 热量平衡

Abstract:

Based on the long term data and information collected from transitional region between oasis and desert at the transitional belt between Badanjilin desert and Tenggeli desert, research on the radiation change characteristics and heat balance law were carried out. All factors of radiation balance in the plot have obvious diurnal and seasonal pattern. The maximum of overall radiation is 12023.3 kW·m^-2in August and the minimum is 5206.5 kW·m^-2 in November. The albedo rate on the vegetation covered surface (such as Tamarix ramosissima,Nitraria tangutorum) is lower than that on the uncovered shifting sand dune, especially at growth season; is sequence of maximum is shifting sand dune(37.5%)>Nitraria tangutorum sand dune(29.7%)>Tamarix ramosissima(27.9%). The net radiation on the shifting sand dune surface is 50%～70% of that on the uncovered shifting sand dune. The biggest proportion in the heat balance is the potential heat flux, followed by sensible heat flux and soil heat flux. With desertification becoming·more serious, while the albedo rate is to increase, net radiation is to decrease in ecosystem; Moreover, the proportion of soil heat flux in heat balance increases, but that of potential heat flux decreases.

Key words: Minqin, Oasis, Desertification, Radiation characteristics, Heat balance