【摘要】 利用2008年、2010年和2012年藏北高原那曲地区MODIS卫星数据和站点大气湍流观测数据,分别应用Massman反演模型和一种确定地表粗糙度的独立方法,计算并分析地表粗糙度的时空变化特征并对反演模型进行验证,分析Z0m存在着明显的季节性变化特征。2—8月伴随冰雪消融与植被生长,Z0m逐渐增大,站点Z0m最大可达4～5 cm。9月至次年2月由于高原季风的衰退期等原因,Z0m逐渐减小,站点Z0m减小至1～2 cm。异常年份的降雪是Z0m明显低于常年的主要原因。依据Z0m的由小到大可以将下垫面分为冰雪类、稀疏草地类、茂盛草地类、城镇类4类,其中茂盛草地类和稀疏草地类分别占区域62. 49%和33. 74%,为主要类别,其Z0m年变化分别在2～6 cm和1～4 cm之间。两种计算方法得出的结论相关性较好,由于平均滑动作用,反演资料较实测计算结果偏小。整体而言,利用卫星数据反演算法计算的Z0m是可行的,并可应用于改进陆面模式参数,提高模式模拟的准确性,能更好的揭示区域的热通量交换。更多还原

【Abstract】 Using the MODIS satellite data and three site turbulent data of the Nagqu region in northern QinghaiTibetan plateau in 2008,2010 and 2012,with the Massman inversion model and an independent method to determine aerodynamic surface roughness,calculate and analyze the dynamic change laws of aerodynamic roughness length and verify the inversion model. The results showthat the aerodynamic roughness length has a dynamic monthly change. From February to August,Z0 mincreases constantly with the ablation of snowand vegetation growth,and the maximum value of sites reaches 4 ～ 5 cm. From September to February,due to the post-monsoon over the plateau,Z0 mgradually decreased,and the values decreased to about 1 ～ 2 cm. Snowfall is the main reason why Z0 mduring this period is significantly lower than normal. The underlying surface can be divided into four categories according to the different values of Z0 m: ice and snow,sparse grassland,lush grassland,and urban.Among them,sparse grassland and lush grassland account for 62. 49% and 33. 74% of underlying surface of the region respectively,and they are the main categories,whose Z0 mfluctuate between 2 ～ 6 cm and 1 ～ 4 cm. The results obtained by the two calculation methods are positively related to each other. Due to the average sliding effect,the inversion results are smaller than the site calculation results. Overall,the way of calculating Z0 musing satellite data in an inversion method is feasible and can be applied to improve the land surface model parameters,the accuracy of the model simulation,and better reveal the heat flux exchange.更多还原