祁连山老虎沟流域冰川下垫面地表特征参数变化特征

Changes of the Characteristic Parameters on Glacial Surface of the Laohugou Basin in the Qilian Mountains

摘要: 冰川近地层地表特征参数是冰川表面能量-物质平衡模型的基础，影响冰川消融模拟的精度，因此开展近地层地表特征参数研究对于准确探讨冰川对气候变化的响应具有重要意义。本论文以祁连山西段典型大陆型冰川——老虎沟12号冰川为例，分析了老虎沟流域的气象变化特征位于冰川积累区海拔5040 m自动气象站资料,确定了消融区冰川表面地表动量和热量粗糙度，动量拖曳系数,热量输送系数，感热和潜热通量输送等地表特征参数及其变化规律，结果表明：(1) 动力学地表粗糙度6~9月月均值分别为2.4、2.1、0.7和0.6mm，热传输附加阻尼(kB−1)具有明显日循环，在正午时分出现最小；(2) 大气层结稳定状态时，动量拖曳系数和热量输送系数6-9月月均值分别为0.001, 0.0009, 0.001和0.001，大气层结不稳定时，两系数都为0.0022；(3) 感热通量绝大多数时间为正值，潜热通量绝大多数时间为负值，两者可相互抵消，观测期间两者的平均值分别为10.4和−12.3 W∙m⁻²。

Abstract: Characteristic parameters of glacier near ground surface based on the glacier surface energy and material balance model have an important influence on the simulation accuracy of glacier ablation. It is significant to study the characteristic parameters of the near surface for the investigation of glacier response to climate change. The changing meteorological characteristics around the Laohugou No. 12 glaciers, as a typical example of continental glacier, have been studied based on the data of automatic meteorological station located at the 5040 m altitude of glacier accumulation area in the west section of Qilian Mountains. And then, the corresponding characteristic parameters including the roughness of momentum and heat, momentum drag coefficient, heat transfer coefficient, and sensible and latent heat flux near glacier surface layer have been analyzed. First, the results showed that the average value of aerodynamic surface roughness attained 2.4, 2.1, 0.7 and 0.6 mm respectively among June to September. The value of heat transfer additional damping (kB−1) presented an obvious daily cycle with a minimum at midday. Second, under different atmospheric conditions, the results presented that the average of momentum drag coefficient and heat transfer coefficient attained 0.001, 0.0009, 0.001 and 0.001 respectively when the atmosphere stratification was stable, otherwise these two coefficients were all 0.002 in the same period. Finally, the flux analysis indicated that the sensible and latent heat flux were always positive and negative, and the average value with 10.4 and −12.3 W∙m⁻², respectively, which could offset each other during the studied period.