航天飞机雷达对阿拉善高原沙漠及次地表岩石的回波响应

Space Shuttle Radar Response from Sand Dunes and Subsurface Rocks of Alashan Plateau

装载在航天飞机哥伦比亚号上的成象雷达1号(SIR-A)于1981年11月进行了成象飞行,三年后的1984年10月航天飞机挑战者号又载变换参数的成象雷达2号(SIR-B)进行了试验。两部雷达均获取了我国内蒙阿拉善高原的图象。这是迄今仅有的中国国土的两批航天雷达图象。它为我们提供了有关沙丘及次地表岩石的新资料。 阿拉善高原是中国最干旱地区之一,包含了全国13个大沙漠中的3个沙漠,大大小小的沙丘极其发育,其中巴丹吉林沙漠拥有世界上最高的沙山,其间亦分布有准平原。

SIR-A and SIR-B images or three sand dunes and two bedrock regions in Alashan Plateau of north central China have been studied and compared to the digital processing Landsat imagery and field investigation data. The results of the study show that radar illuminating direction is a key factor, which results in the echo strength change for the same type and size of sand dunes. The sand dunes in which the slipfaces are oriented to radar beam have a bright-point response and the dunes in which the gentle slopes face the radar beam have a dark signature on the radar images. Two Precambrian metamorphic rock bodies buried beneath the thin layer of alluvial material or aeolian sand have been detected by using the spaceborne radar imagery. A preliminary scattering model was given to explain the imaging mechanism.