A Pol-SAR Analysis for Alpine Glacier Classification and Snowline Altitude Retrieval

作者：Callegari, Mattia^*; Carturan, Luca; Marin, Carlo; Notarnicola, Claudia; Rastner, Philipp; Seppi, Roberto; Zucca, Francesco

来源：IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2016, 9(7): 3106-3121.

DOI：10.1109/JSTARS.2016.2587819

• Glacier
• polarimetric synthetic aperture radar (SAR)
• support vector machines (SVM)

In this study, we investigated the use of synthetic aperture radar (SAR) polarimetry (Pol-SAR) and a supervised classification technique, support vector machine (SVM), for the classification of bare soil, ice, and snow, over the Ortles-Cevedale massif, (Eastern Italian Alps). We analyzed the importance of topographic correction on the backscattering and polarimetric SAR signature and the advantage of quad-pol with respect to dual-pol data. When backscattering values only are employed, the incidence angle used as input feature of the SVM classifier assures the best classification accuracy, 9.9% higher than the accuracy obtained with cosine corrected gamma(0) backscattering. The introduction of polarimetric features and decomposition parameters (such as Cloude-Pottier or Touzi decomposition parameters) increases the classification accuracy by 5.2% with respect to the backscattering case. The simulation of RADARSAT-2 data as Sentinel-1 like for dual-pol data shows a decrease of accuracy equal to 7.8% with respect to the fully polarimetric case (93.5%). The first Sentinel-1 image acquired on our test area was also employed for classification. We then tested the capability of C-band SAR to detect accumulation and ablation zones of the glaciers under the winter dry snow by setting up a multi-incidence angle and fully polarimetric SVM classifier, exploiting ascending and descending RADARSAT-2 data. In this case, the accuracy increased by 14.7% combining different geometric acquisitions (88.9%) with respect to the single geometry case. Finally, from the resulting classification maps, we extracted the snowline altitude for a sample of three glaciers, using both optical and SAR data, comparing the different products.

• 出版日期2016-7
• 单位中国科学院遥感与数字地球研究所