李斐,,
张胜凯,
郝卫峰,
耿通,
宣越
武汉大学中国南极测绘研究中心, 武汉 430079
基金项目: 国家重点研发计划（2017YFA0603102），国家自然科学基金项目（41531069，41730102，41706216），武汉大学自主科研项目交叉学科类（2042017kf0209）联合资助
详细信息
作者简介: 肖峰, 男, 1989年生, 博士后, 主要从事极地卫星大地测量学等方面的研究.E-mail:shaw89@whu.edu.cn
通讯作者: 李斐, 男, 1960年生, 教授, 博导, 主要从事行星内部构造、重力场及极地大地测量学等方面的教学与研究.E-mail:fli@whu.edu.cn
中图分类号: P228收稿日期:2019-07-29
修回日期:2020-03-02
上线日期:2020-08-05
DEM generation for the Lambert Glacier-Amery Ice Shelf system, East Antarctica, from CryoSat-2 waveform data
XIAO Feng,LI Fei,,
ZHANG ShengKai,
HAO WeiFeng,
GENG Tong,
XUAN Yue
Chinese Antarctic Center of Surveying and Mapping, Wuhan University, Wuhan 430079, China
More Information
Corresponding author: LI Fei,E-mail:fli@whu.edu.cn
MSC: P228--> Received Date: 29 July 2019
Revised Date: 02 March 2020
Available Online: 05 August 2020
摘要
摘要:Lambert冰川-Amery冰架系统是南极冰盖最大的冰流系统之一，对南极冰盖物质平衡研究有着重要的作用.数字高程模型（DEM）是进行南极冰盖研究的基础.本文基于CryoSat-2 L1b波形数据，研究建立了Lambert冰川流域高分辨率DEM.测高卫星返回波形在冰盖区域存在变形，需进行波形重跟踪处理.利用交叉点分析方法对重心偏移法（OCOG）、阈值法和β参数法等常用的波形重跟踪方法对不同类型的CryoSat-2波形的适用性进行了研究.最后，利用克里金插值方法建立了500 m分辨率的Lambert冰川流域DEM——LAS DEM（Lambert Glacier-Amery Ice Shelf system DEM）.利用ICESat卫星测高数据和GPS地面实测数据对LAS DEM进行精度验证，并与另外两种基于CryoSat-2数据的南极DEM进行了对比.结果表明：LAS DEM的整体精度约为0.295±2.7 m，优于另外两种CryoSat-2 DEM；在冰盖内陆地区，LAS DEM的高程误差在2 m之内；在Amery冰架上，LAS DEM的精度优于1 m.
关键词: CryoSat-2/
数字高程模型/
Lambert冰川流域/
波形重跟踪/
南极
Abstract:The Lambert Glacier-Amery Ice Shelf system is a major component of the Antarctic ice sheet. Satellite altimeters are currently the most suitable instrument available for ice sheet mapping at the desired accuracy and spatial and temporal resolution for geoscientific and environmental studies. Due to the newly developed SIRAL instrument, CryoSat-2 has a significant improvement compared to the conventional altimeters and enables continuous observations along the relatively steep and narrow margins of the ice sheets as well as on large glaciers and ice caps, where elevation change is most rapid. This paper presents a 500 m digital elevation model for the Lambert-Amery system using CryoSat-2 radar altimeter waveform data.
The range accuracy of the altimeter is degenerated over the ice sheet due to waveform contamination. Retracking methods including the OCOG (Offset Center of Gravity) method, the threshold method with 10%, 25% and 50% threshold level, the linear and exponential 5-β parametric methods are compared using crossover analysis over the Lambert-Amery system. For LRM (Low Resolution Mode) waveforms, the linear 5-β parametric method is applied. The threshold method with 25% threshold level and the OCOG method are carried out for SARIn waveforms over margins of the ice sheet and the Amery Ice Shelf, respectively. For the LRM data we follow an iterative approach to correct for the surface slope, and the slope correction is applied to each data point using the relocation method. Finally, we produce a new DEM for the Lambert-Amery system using ordinary Kriging interpolation.
The accuracy of the DEM is assessed by ICESat data and GPS data and compared with two Antarctic DEMs based on CryoSat-2. The results show that the new DEM has the highest accuracy with an uncertainty of 0.295±2.7 m. The vertical accuracy of the DEM is better than 2 m for the interior ice sheet and better than 1 m for the Amery Ice Shelf. The accuracy degenerates in the grounding area because of the sloped topography and fast ice flows.
Key words:CryoSat-2/
Digital elevation model/
Lambert Glacial-Amery Ice Shelf system/
Waveform retracking/
Antarctic
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