摘要
在格陵兰冰盖北部溢出冰川以外的地区,竖井和注水冰裂隙较少分布,冰面融水被直接汇流至冰前区域形成冰前水系,最终汇入海洋,形成独特的冰面—冰前融水汇流过程,这对冰盖物质平衡以及海洋环境变化产生重要影响。卫星遥感能够直接观测冰面融水径流和冰前水系的时空分布,提供河流位置、形态、动态变化等关键信息,已成为研究格陵兰冰盖融水汇流过程的重要手段。本研究以格陵兰冰盖北部地区Denmark冰面—冰前流域(3240 km2)作为研究对象,采用Sentinel-2和Landsat 8卫星影像提取研究区2014年—2021年消融期(6—8月)冰面融水范围与流域出口冰前河宽,分析冰面融水与冰前河的季节与年际变化特征。进一步对比遥感观测的冰面—冰前流域融水与区域气候模型(MARv3.12与RACMO2.3p2)模拟的冰面融水径流量,揭示冰面—冰前融水汇流过程对冰面消融强度的响应。结果表明:(1)消融期内,冰面融水范围首先向高海拔地区推进(最高海拔达约1400 m),随后逐步消退至冰盖边缘至约500 m,流域出口冰前河宽呈现先增大至约2000 m后减小至约100 m的变化趋势;(2)遥感观测的冰面融水与流域出口冰前河宽呈现显著线性正相关关系(R=0.87,P<0.01),流域内形成了连续的冰面—冰前水文系统,能够有效汇流融水离开冰盖进入海洋;(3)MARv3.12与RACMO2.3p2模型能够较准确地模拟冰面融水径流量,冰面融水径流量与遥感观测的冰面融水(MAR:R=0.87;RACMO:R=0.84,P<0.01)以及流域出口冰前河宽(MAR:R=0.89;RACMO:R=0.88,P<0.01)均具有较强的相关性。(4)考虑融水汇流滞时的冰面融水径流量与流域出口冰前河宽的相关系数(MAR:R=0.94;RACMO:R=0.92,P<0.01)提升,显著高于瞬时冰面融水径流量对应的相关系数,Denmark流域冰面—冰前融水汇流过程的最优滞时约为2 d,这一滞时定量表征了Denmark流域冰面—冰前流域输送融水的效率。
Mass loss from the Greenland Ice Sheet(GrIS)has accelerated in recent decades,with profound effects on global sea-level rise.During each summer,the meltwater forms supraglacial rivers and then is transported to the proglacial zone,eventually flowing into the ocean and forming a continuous supraglacial-proglacial river system.This continuous supraglacial-proglacial drainage system directly results in the mass loss of the GrIS and has an important impact on the changes in the marine environment.Satellite images can directly observe the temporal and spatial distribution of supraglacial and proglacial rivers and have been widely used in the study of the GrIS.The satellite-derived observation can provide key information,such as the location,morphology,and dynamic changes of rivers.It has become an important way to analyze meltwater routing.In this study,361 scenes of Sentinel-2 and Landsat 8 satellite images are used to extract the supraglacial and proglacial rivers in the Denmark supraglacial-proglacial basin of the northeastern GrIS during the melt seasons(from July to August)and monitor their spatial distribution and dynamic changes.Furthermore,satellite-derived observation and meltwater runoff simulated by regional climate models(MARv3.12 and RACMO2.3p2)are compared and analyzed,and then the lag time of the supraglacialproglacial drainage system is estimated.The main contents and conclusions of this study include the following three aspects:(1)The proglacial river width is in the range of 100—2000 m and experiences a seasonal trend.The ice surface meltwater shows similar variation characteristics,advancing to the high-altitude areas of the ice surface(up to~1400 m)at the initial stage of ablation,and then gradually receding to the edge of the ice sheet(up to~500 m).(2)A significant positive correlation is found between satellite-derived proglacial river width and meltwater on the ice surface(R=0.87,P<0.01),forming a continuous supraglacial-proglacial drainage system that can effectively transport the meltwater e
作者
李雅
杨康
刘金昱
张闻松
王裕涵
LI Ya;YANG Kang;LIU Jinyu;ZHANG Wensong;WANG Yuhan(School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China;The 54th Research Institute of China Electronics Technology Group Corporation,Shijiazhuang 050081,China;Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology,Nanjing 210023,China;Collaborative Innovation Center of South China Sea Studies,Nanjing 210023,China)
出处
《遥感学报》
EI
CSCD
北大核心
2024年第6期1433-1452,共20页
NATIONAL REMOTE SENSING BULLETIN
基金
国家自然科学基金(编号:42271320)
中国科学院战略性先导科技专项(编号:XDA19070201)。
关键词
冰面消融
冰面河
冰前河
河流遥感
极地遥感
格陵兰冰盖
ice melting
supraglacial river
proglacial river
river remote sensing
polar remote sensing
Greenland ice sheet
