额济纳旗东北区戈壁面粗糙度分形特征与雷达遥感实证分析

Analysis of Radar Wave Back Scatter Coefficient for Fractal Feature of Roughness Surface of Gobi in North-eastern Ejina Qi,Inner Mongolia

反映地表粗糙状况特征量的地表粗糙度是非线性的 ,可以用分形去刻划。雷达遥感具有对地表粗糙度敏感的特性 ,故利用美国航天飞机 3号 ( SIR- C/ X- SAR)雷达遥感数据 ,选择干燥的内蒙古额济纳旗东北区作为雷达回波与地表粗糙度分形测量研究实验区。实测的计算结果表明 ,在 2～ 10 cm无标度区间 ,此处的戈壁面为具有分形特征的粗糙地形面 ,从雷达遥感的后向散射系数分析表明 ,该区对 C波段 (λ =5 .3 cm) HH极化回波贡献非常强烈 ,其原因是 2～ 10 cm区间尺度正好含盖航天飞机雷达波 C波段长度 ,而小于 L波段 (λ=2 3 .5 cm )长度 ,此结论实证了戈壁地貌表面在一定区间具有分形的特征 ,并可以为雷达遥感某一波段所强烈表现出来 ,这将为借助分数维对图像处理、地物分类以及表面侵蚀定量刻划提供重要的科学依据。

Surface roughness degree which represents characteristic quantity of grade of land surface roughness is nonlinear, and can be described by fractal dimension. Radar remote sensing has sensibility for condition of land surface roughness. Using SIR-C/X-SAR radar imagery, a experimental site for research the relationship between back-scatter wave and surface roughness coefficient (SRC) described by fractal dimension is chosen at northeast of Ejinaqis Gobi in Inner Mongolia. As computing, the result shows that the Gobi surface has feature of fractal in 2～10cm non-scale district. Analyzing from radar images displays that back wave of HH polarization ofCband length(λ=5.3cm) is very intensity in researching area. Its reason is that the scale district of 2～10 cm covers Cband length (λ=5.3cm) of SIR-C/X-SAR,and less than Lband length (λ=23.5cm).The result proves that Gobis surface has fractal feature in some scale district. The phenomenon is presented in radar remote sensing imagery. The research will contribute important scientific support to processing imaging and sorting ground objects and describing the states of erosion of land surface, etc.