基于ICESat数据的南极冰盖DEM插值方法比较及精度分析

南极数字高程模型(DEM)是从事南极地学和环境变化研究的基础. 内插是建立数字高程模型的重要技术点, 插值方法有多种, 根据不同的适用情况, 不同的插值方法各有优劣. 利用克里格、 距离反权、 三角网剖分、 最小曲率以及移动平均5种插值方法分别建立南极冰盖小范围区域的DEM, 通过抽取部分观测数据作为验证值对各插值方法进行了比较. 结果表明: 克里格插值方法的可靠性最好, 稳定性最高. 然后, 利用克里格插值方法, 基于ICESat测高卫星的GLA12数据建立了南极冰盖的DEM. 由于南极大陆实测数据有限, 缺乏对DEM的检核. 为了分析所建DEM的可靠性, 利用中国南极内陆冰盖考察所采集的GPS实测数据, 对所建立的DEM进行了验证分析. 结果显示, DEM在坡度较缓的南极内陆冰盖区域精度较高, 符合度在3 m以内; 距离卫星轨道越近的区域精度越高, 可达到1 m 以内. 在坡度较大, 高程变化较为显著的区域如沿海地区, 精度较低, 差距最大的点超过40 m.

Comparing the interpolation algorithms and analyzing the accuracy of a digital elevation model of the Antarctic ice sheet based on ICESat data

The Antarctic digital elevation model (DEM) is an important data set for the Antarctic geosciences and environmental change research. The interpolation algorithm is the core issue in the data processing of DEM. There are several interpolation algorithms. DEMs in two small regions in Antarctic ice sheet were created by using five different interpolation algorithms, including Kriging (KRI), Inverse Distance to a Power (IDP), Triangulation with Linear Interpolation (TLI), Minimum Curature (MC) and Moving Average (MA) algorithm. The DEMs were validated against the sample data which was reserved from the survey data for comparison. The results indicate that Kriging algorithm has the best reliability and the highest stability. A new DEM of the Antarctic Ice Sheet has been derived from ICESat Data using Kriging algorithm. The uncertainty of the DEM was assessed using GPS data collected by the Chinese National Antarctic Research Expedition to Inland. The results show that the precision of the DEM is closely correlated with the slop and coverage; the DEM is in good agreement with the GPS data over the small slope areas and the areas nearby the satellite orbit.