Abstract Radar backscattering coefficients from synthetic aperture radars and scatterometers are commonly used to characterize the land surface properties and monitor their temporal evolution. Radar altimetry is mostly used, over land, to provide time series of water stage of lakes, rivers and wetlands and the topography of the ice sheets. Very few studies used the radar altimetry backscattering coefficients for geophysical applications except to determine changes in Arctic lakes state surface, surface soil moisture in semi-arid environments or flood extent at high latitude. As radar altimetry missions acquired data in four frequency bands (mostly C and Ku but also S and Ka), this study proposes the first thorough analysis of the backscattering signatures of land surfaces using observations from ERS-2, Jason-1, ENVISAT, Jason-2 and SARAL radar altimetry missions The spatial and temporal variations of several altimetric information (backscattering coefficient, waveform peakiness, leading edge width and trailing edge slope) are examined at global scale, for each frequency band separately, as well as for their differences. Their relationship with related variations in the surface characteristics (i.e., soil type, soil moisture, presence of water and snow) are evidenced. Finally, spatial patterns and temporal variations computed over selected regions, representative of the major bioclimatic areas, are related to their surface properties and changes.

中文翻译：

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来自陆地上低分辨率雷达测高仪的 ka、ku、c 和 s 波段的反向散射特征

摘要 合成孔径雷达和散射仪的雷达后向散射系数通常用于表征地表特性并监测它们的时间演变。雷达测高主要用于陆地上的湖泊、河流和湿地水位以及冰盖地形的时间序列。除了确定北极湖泊状态表面、半干旱环境中的表层土壤湿度或高纬度洪水范围的变化外，很少有研究将雷达测高后向散射系数用于地球物理应用。由于雷达测高任务在四个频段（主要是 C 和 Ku，但也有 S 和 Ka）获取数据，因此本研究提出了使用 ERS-2、Jason-1、ENVISAT、Jason-2 和 SARAL 雷达测高任务在全球范围内分别针对每个频段检查了几个高度信息（后向散射系数、波形峰值、前沿宽度和后沿斜率）的空间和时间变化，以及它们的差异. 它们与地表特征（即土壤类型、土壤湿度、水和雪的存在）的相关变化之间的关系得到了证明。最后，在代表主要生物气候区的选定区域上计算的空间模式和时间变化与其表面特性和变化有关。分别为每个频段，以及它们的差异。它们与地表特征（即土壤类型、土壤湿度、水和雪的存在）的相关变化之间的关系得到了证明。最后，在代表主要生物气候区的选定区域上计算的空间模式和时间变化与其表面特性和变化有关。分别为每个频段，以及它们的差异。它们与地表特征（即土壤类型、土壤湿度、水和雪的存在）的相关变化之间的关系得到了证明。最后，在代表主要生物气候区的选定区域上计算的空间模式和时间变化与其表面特性和变化有关。