基于PlanetScope影像的格陵兰冰面融水监测  

Surface meltwater on the Greenland ice sheet mapped from PlanetScope small satellite imagery

作　　者：朱雨欣 张闻松 杨康[1,2,3] Zhu Yuxin;Zhang Wensong;Yang Kang(School of Geography and Ocean Science,Nanjing University,Nanjing 210023,China;Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology,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》2023年第4期508-516,共9页Chinese Journal of Polar Research

基　　金：国家自然科学基金(41871327);中国科学院战略性先导科技专项(XDA19070201)资助。

摘　　要：格陵兰冰盖的消融及其对海平面上升的贡献成为国际上研究的热点。每年消融期,格陵兰冰盖表面消融,融水会导致冰面形成冰面湖、冰面河、注水冰裂隙等形态。格陵兰冰面融水规模庞大、结构复杂、变化迅速,区域气候模型难以准确模拟冰面融水分布,中等分辨率卫星影像难以反映冰面融水的时空变化。以PlanetScope为代表的CubeSat小卫星空间分辨率高达3 m,理想情况下重访周期可达1 d,这为精细化动态监测格陵兰冰面融水提供了可能。本研究利用PlanetScope高空间分辨率小卫星遥感影像提取格陵兰冰盖西南部典型流域冰面融水遥感信息,构建了针对PlanetScope遥感影像的冰面融水深度反演公式,对比了MAR v3.11区域气候模型模拟的融水径流量与遥感反演的融水体积。结果表明:在2019年7—8月,流域内冰面融水开放水体比率先上升后下降,在7月12日达到峰值8.7%;流域内冰面融水深度介于0.2~1.5 m之间,冰面湖最深(0.9 m±0.2 m),冰面河干流次之(0.6 m±0.1 m),冰面河支流最浅(0.5 m±0.1 m);遥感观测的开放水体比率、冰面融水体积与区域气候模型MAR模拟的融水日径流量具有正相关关系,故融水径流对于冰面湖与冰面河具有直接供给作用;流域冰面融水存储比例(遥感观测的冰面融水体积与模型模拟的融水累积径流量之比)先升高后降低,冰面融水储存比例小于1%,储存能力十分有限,冰面流域能够高效输送融水进入冰盖内部。Surface melt of the Greenland ice sheet and its impact on rising sea levels have become hot topics in international research.Each summer,surface meltwater forms on the Greenland ice sheet,forming supraglacial lakes,supraglacial rivers,and water-filled crevasses.There is a large area of surface meltwater,which exhibits complex structure,and changes rapidly over time.Regional climate models do not accurately simulate the distribution of surface meltwater,and medium resolution satellite images may not reflect spatial and temporal changes in surface meltwater.CubeSats,such as PlanetScope,allow dynamic monitoring of surface meltwater by providing near-daily satellite observation at 3 m spatial resolution.In this study,we extracted surface meltwater in a typical internally drained catchment in the southwest Greenland ice sheet using PlanetScope images.We then constructed a formula to estimate meltwater depth from the PlanetScope images and compared meltwater volume estimated by satellite images and meltwater runoff simulated by the MAR v3.11 model.The results showed that the open water fraction(OWF)of surface meltwater in the catchment first rose then decreased during July and August 2019,peaking on 12 July(8.7%).The surface meltwater depth in the catchment ranged from 0.2 to 1.5 m,and the supraglacial lakes were the deepest(0.9 m±0.2 m),followed by the mainstem of supraglacial rivers(0.6 m±0.1 m),and the tributaries of supraglacial rivers(0.5 m±0.1 m).The OWF,meltwater volume and daily runoff simulated by MAR were positively correlated,indicating that meltwater runoff directly supplies supraglacial lakes and rivers.The surface meltwater storage capacity is limited(<1%),and the catchment is efficiently transporting meltwater into the ice sheet.

关 键 词：冰面融水 PlanetScope 遥感观测 区域气候模型 格陵兰冰盖 

分 类 号：P237[天文地球—摄影测量与遥感] P343.6[天文地球—测绘科学与技术]