Near-coastal circum-Antarctic iceberg size distributions determined from Synthetic Aperture Radar images
Near-coastal circum-Antarctic iceberg size distributions determined from Synthetic Aperture Radar images
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DOI：
10.1016/j.rse.2014.10.025
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发表时间：
2015-01-01
影响因子：
13.5
通讯作者：
Dierking, Wolfgang
中科院分区：
文献类型：
--
作者：
Wesche, Christine;Dierking, Wolfgang
雷达卫星1号南极测绘项目根据1997年9月和10月获得的3，000多幅高分辨率合成孔径雷达图像汇编了南极洲和邻近海洋区的镶嵌图。像素大小为100米的镶嵌图用于确定南极洲周围的冰山大小分布，将自动检测与所有大于5公里的冰山的视觉控制相结合（2），并纠正已识别的错误检测。对于小于5公里（2）的大小的冰山，错误的检测和大小检索的准确性进行了分析的三个测试站点。近7000个冰山的水平面积在0.3和4717.7公里（2）之间，在近海岸带的宽度在20和300公里之间。计算了南极洲周围20 °角宽的带状段的冰山空间分布，并与各断面的冰解锋面类型有关。结果表明，粒径分布的区域差异不容忽视。最大的冰量积累出现在巨大冰山的位置（>18.5公里），但也出现在冰架的前面，大量较小的冰山几乎不断地从冰架上崩解。虽然与海洋学研究所需的空间覆盖范围相比，RAMP覆盖的沿海海洋区太窄，但这项研究表明，合成孔径雷达图像对冰山研究是有用的，而且需要从海岸向海洋延伸500公里以上的距离重复获取数据，以监测冰山融化和解体以及相关的淡水流入海洋。(C)2014爱思唯尔公司All rights reserved.
The Radarsat-1 Antarctic Mapping Project (RAMP) compiled a mosaic of Antarctica and the adjacent ocean zone from more than 3000 high-resolution Synthetic Aperture Radar (SAR) images acquired in September and October 1997. The mosaic with a pixel size of 100 m was used to determine iceberg size distributions around Antarctica, combining an automated detection with a visual control of all icebergs larger than 5 km(2) and correction of recognized false detections. For icebergs below 5 km(2) in size, the numbers of false detections and accuracies of size retrievals were analyzed for three test sites. Nearly 7000 icebergs with horizontal areas between 0.3 and 4717.7 km(2) were identified in a near-coastal zone of varying width between 20 and 300 km. The spatial distributions of icebergs around Antarctica were calculated for zonal segments of 20 degrees angular width and related to the types of the calving fronts in the respective section. Results reveal that regional variations of the size distributions cannot be neglected. The highest ice mass accumulations were found at positions of giant icebergs (>18.5 km) but also in front of ice shelves from which larger numbers of smaller icebergs calve almost continuously. Although the coastal oceanic zone covered by RAMP is too narrow compared to the spatial coverage needed for oceanographic research, this study nevertheless demonstrates the usefulness of SAR images for iceberg research and the need for repeated data acquisitions extending ocean-wards over distances of 500 km and more from the coast to monitor iceberg melt and disintegration and the related freshwater input into the ocean. (C) 2014 Elsevier Inc. All rights reserved.