基于地形指数的格陵兰冰面水系建模与评价  

MODELING SUPRAGLACIAL RIVER NETWORKS ON THE GREENLAND ICE SHEET USING THE TOPOGRAPHIC INDEX

作　　者：毛玮 陆欣 陆瑶 杨康[1,2,3] Mao Wei;Lu Xin;Lu Yao;Yang Kang(School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China;Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology,Nanjing University,Nanjing 210023,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519080,China)

机构地区：[1]南京大学地理与海洋科学学院,江苏南京210023 [2]江苏省地理信息技术重点实验室,江苏南京210023 [3]南方海洋科学与工程广东省实验室(珠海),广东珠海519080

出　　处：《极地研究》2021年第3期351-362,共12页Chinese Journal of Polar Research

基　　金：国家重点研发计划(2018YFC1406101);国家自然科学基金(41871327);中央高校基本科研业务费项目(14380070)资助。

摘　　要：每年消融期,冰面融水通过冰面水系输送至冰盖边缘,造成格陵兰冰盖物质损失。冰面水系的动态变化决定了冰面融水输送的方式与效率,显著影响格陵兰冰盖物质平衡。作为决定冰面水系动态变化的关键因素之一,冰面地形对冰面水系动态变化的控制程度有待研究。本研究选取格陵兰冰盖西南部典型区域(~1800km^(2))作为研究区,以32m空间分辨率ArcticDEM作为实验数据,利用地形湿度指数(Topographic Wetness Index, TWI)和最邻近河网高差指数(Height Above the Nearest Drainage, HAND)两种地形指数模拟冰面水系分布,结合2016—2019年消融期29景10 m空间分辨率Sentinel-2和30 m空间分辨率Landsat-8影像提取冰面水系作为验证数据,通过模糊比较揭示了地形指数建模冰面水系的精度。研究结果表明:地形指数能够较好地建模冰面水系分布(总体精度>72%),冰面水系分布主要受地形因素控制,将地形指数引入冰面水文的研究,有助于加强对于冰面水文过程的理解。During the annual ablation period,a large amount of meltwater is transported to the margin of the Greenland ice sheet through supraglacial river networks,causing mass loss from the Greenland ice sheet.The dynamics of supraglacial river networks determine the flowpath and efficiency of meltwater routing,and significantly affect the mass balance of the Greenland ice sheet.As one of the key factors that determines the dynamics of supraglacial river networks,the control of the ice surface topography on the supraglacial river network’s dynamics remain unknown.In this study,we modeled the distribution of supraglacial river networks on a typical melting region of the southwest Greenland ice sheet(approximately 1800 km^(2))using the Topographic Wetness Index and the Height Above the Nearest Drainage method derived from the 32 m Arctic DEM.The modeling results were validated and compared with the frequency observations compiled from 29 scenes acquired from Sentinel-2 imagery at 10-m resolution and Landsat-8 imagery at 30-m resolution.The results show that the Topographic Wetness Index(TWI)and Height Above the Nearest Drainage(HAND)method can be used to model the spatial distribution of the Greenland ice sheet supraglacial river network with an overall accuracy greater than 72%;therefore,the spatial distribution of the supraglacial river network is mainly controlled by the ice surface topography.As shown here,applying topographic indices in the study of supraglacial hydrology can help to improve the understanding of supraglacial hydrological processes.

关 键 词：冰面水系 地形湿度指数 最邻近河网高差指数 Sentinel-2 Landsat-8 格陵兰冰盖 

分 类 号：P343.6[天文地球—水文科学] P467[天文地球—地球物理学]