黄河源头玛多县高寒草甸地表辐射平衡及土壤热状况变化规律研究

摘要

【Objective】 The characteristics of surface radiation budget and soil heat condition of the alpine grassland in the Yellow River source region was analyzed to provide scientific basis for the environmental development and macroscopic decision of ecological fragile region in the Yellow River source region.【Method】 The surface global radiation,net radiation,reflected radiation,effective radiation,albedo and soil heat condition on alpine grassland in Maduo were analyzed using the data observed at Maduo station from November 2009 to October 2010.【Result】 The results showed that each radiation component varied significantly.Global radiation,net radiation and effective radiation were the strongest in summer and the weakest in winter except reflected radiation.The value of albedo in spring,summer,autumn and winter barely changed and havd a U-shape curve.The daily variation was relative to solar altitudinal angle.Soil temperature gradient was negative from October to and positive from to September.Maximum of soil temperature gradient occured in January while minimum occurred in July.The correlative coefficient between soil temperature and net radiation was-0.815 with confidences of 0.01.The soil heat flux fluctuated faster in the shallow soil layer and slower in the deep soil layer.【Conclusion】 The surface global radiation,net radiation,reflected radiation,effective radiation,albedo and soil heat condition on alpine grassland in Yellow River source region changed as the height of the sun angle changed.Minimum values appeared in the daytime and maximum values appeared in the night.The soil heat flux in spring and summer was positive,which indicated that during this time soil was heat sink.In contrast,the heat transfer was from soil to the atmosphere in winter.%【目的】分析黄河源头玛多县典型高寒草甸地表辐射及土壤热状况的变化特征,为黄河源头极其脆弱的高寒草甸发展方向和宏观决策提供依据。【方法】根据黄河源头玛多县典型高寒草甸观测点2009-11-01-2010-10-31每天5min的观测资料,分析玛多高寒草甸辐射及土壤热状况的变化特征。【结果】玛多地区各辐射分量均存在明显的变化特征,除反射辐射外,总辐射、有效辐射和净辐射均在夏季达到最高值,各辐射分量的日变化呈现典型的单峰结构。春夏秋冬地表反射率变化幅度较小,总体均呈＂U＂型变化,其日变化与太阳高度角关系密切。土壤温度梯度在1月份最大,7月份最小;10-4月土壤温度梯度为负值,4-9月为正值。土壤温度梯度与地表净辐射的相关系数为-0.815,通过了0.01的置信度检验。土壤热通量在表层（10cm）振荡比较明显,说明表层热通量易受外界影响,而在30cm及以下土层土壤热通量变化幅度较小。【结论】黄河源头高寒草甸总辐射、净辐射、反射辐射和有效辐射均随太阳高度角的变化而变化,最小值出现在夜间而最大值出现在白天。土壤热通量在春季和夏季均为正值,土壤热量从浅层土壤向深层乃至更深层传输,这段时间内土壤是热量的＂汇＂,冬季则相反。