基于北极多源卫星数据的海冰厚度时空变化对比与评估

Comparison and assessment of data on multi-source satellite remote sensing Arctic sea ice thickness

海冰厚度作为海冰的重要变量之一,相较于海冰密集度、海冰漂移速度、海冰范围等,数据时空完整性仍然不足。当前获取北极海冰厚度的主要手段为卫星遥感,除之前的CryoSat-2、SMOS等卫星,2018年11月又新增了ICESat-2卫星。目前,针对北极多源卫星海冰厚度的时空变化差异性对比以及数据精度评估的工作较少,因此,本研究通过选取最近的完整两年(2019—2020年)内的ICESat-2、CryoSat-2以及CS2SMOS(CryoSat-2和SMOS融合产品)海冰厚度数据进行对比分析,量化其时空差异。结果显示,整体上CryoSat-2卫星数据的平均海冰厚度最大,ICESat-2其次,CS2SMOS最小。三种卫星数据间的差异具有明显的时空变化特征,在海冰厚度高值区ICESat-2数据的厚度最大,CryoSat-2与CS2SMOS数据的厚度相近,而在海冰边缘区CryoSat-2数据的厚度最大,CS2SMOS最小。从区域来看,不同卫星数据反演的海冰厚度在东西伯利亚海和波弗特海区域差异较小,在巴伦支海区域差异较大。在此基础上,利用研究时段内的“冰桥行动”实地观测数据对多源卫星数据进行评估,结果表明,2019年4月CS2SMOS数据整体上与实地观测数据更接近,而ICESat-2数据与实地观测数据相差较大。

Sea ice thickness is one of the important variables of sea ice.Our knowledge of the temporal and spatial integrity of sea ice thickness is still insufficient and lags behind that of sea ice concentration,extent,and drift velocity.At present,Arctic sea ice thickness data are mostly obtained by satellite remote sensing using CryoSat-2 and SMOS,and since November 2018,ICESat-2.Few studies have evaluated the accuracy of the latest multi-source satellite Arctic sea ice thickness data or assessed the spatial and temporal differences of data from different sources.In this study,we quantified the spatial and temporal differences between the latest sea ice thickness data from ICESat-2,CryoSat-2,and CS2SMOS(merged product of CryoSat-2 and SMOS)during 2019–2020.Results show that the mean sea ice thickness is largest in CryoSat-2,second largest in ICESat-2,and smallest in CS2SMOS.There are also considerable temporal and spatial differences.For regions covered with thick sea ice,thickness is largest in ICESat-2,and the thickness in Cryosat-2 is similar to that in CS2SMOS.For marginal ice zones,thickness is largest in CryoSat-2 and smallest in CS2SMOS.The difference between the datasets is smaller over the East Siberian Sea and Beaufort Sea and larger over the Barents Sea.We compared the satellite data with field data collected during Operation Ice-Bridge(OIB)in April 2019 and found that the difference between CS2SMOS and OIB is smaller than that between ICESat-2 and OIB.