Pi-SAR-L2 Observation of the Landslide Caused by Typhoon Wipha on Izu Oshima Island
Pi-SAR-L2 Observation of the Landslide Caused by Typhoon Wipha on Izu Oshima Island
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Pi-SAR-L2 伊豆大岛台风威帕引发山体滑坡观测
DOI：
10.3390/rs8040282
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
M. Shimada
中科院分区：
文献类型：
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作者：
Manabu Watanabe;R. Thapa;M. Shimada
分析了2013年10月16日台风威帕引起的伊豆大岛滑坡区四个不同观测方向上观测到的Pi-SAR-L2全极化数据，以阐明检测滑坡区最合适的L波段全极化参数和观测方向。日本的机载Pi-SAR-L2和PiSAR-L数据用于本分析。计算了几个L波段全极化参数，包括后向散射系数（σ°）、两个极化状态之间的相干性、四分量分解参数（双反射/体积/表面/螺旋散射）和特征值分解参数（熵/α/各向异性），以确定最适合检测滑坡区域的参数。α能较好地反映灾前森林到灾后裸地的土地覆被变化，HH与VV具有较好的一致性。从滑坡底部到顶部的观测数据很好地检测到了滑坡，而从相反两侧的观测则没有那么有用，这表明较小的局部入射角更好地区分滑坡和森林地区。滑坡的土壤侵入到城市地区，但是，没有充分的极化参数表现出任何显着差异的滑坡影响的城市地区在灾害发生后，未受影响的地区在灾害发生前。
Pi-SAR-L2 full polarimetic data observed in four different observational directions over a landslide area on Izu Oshima Island, induced by Typhoon Wipha on 16 October 2013, were analyzed to clarify the most appropriate L-band full polarimetric parameters and observational direction to detect a landslide area. Japanese airborne Pi-SAR-L2 and PiSAR-L data were used in this analysis. Several L-band full polarimetric parameters, including backscattering coefficient (σ°), coherence between two polarimetric states, four-component decomposition parameters (double-bounce/volume/surface/helix scattering), and eigenvalue decomposition parameters (entropy/α/anisotropy), were calculated to determine the most appropriate parameters for detecting landslide areas. The change in land cover from forest before the disaster to bare soil after the disaster was detected well by α, and coherence between HH and VV. Observational data from the bottom to the top of the landslide detected the landslide well, whereas observations from the opposite sides were not as useful, indicating that a smaller local incident angle is better to distinguish landslide and forested areas. Soil from the landslide intruded into the urban areas; however, none of the full polarimetric parameters showed any significant differences between the landslide-affected urban areas after the disaster and unaffected areas before the disaster.