城市扩展强度及其地表热特性遥感定量分析

城市化将自然景观转变为不同土地利用的城市景观，改变了地表的物理特性。因此，有关城市扩张及其对环境的影响的准确信息具有广泛的应用价值。利用遥感技术监测土地利用变化成为城市环境研究的重要内容，然而利用遥感技术定量提取城市扩展及其强度的定量信息仍存在许多挑战。本文提出了定量确定城市扩展范围及其发展强度的新方法——地图密度指数。并以中部城市——长沙为例，利用Landsat TM/ETM+数据定量评价了城市扩张及其热环境特征的变化。首先，集成遥感光谱指数提取地表非渗透表面，然后利用移动窗口算法获得地图密度指数，再根据设定的阈值获得密度指数等级图，依此密度指数等级图识别城市扩展范围及其发展强度。再结合地表温度反演的数据，分析了城市格局及其变化与地表热特性变化的定量关系。结果表明，自1990年代以来，长沙市城市区域及其发展密度显著增加，城市发展的密度差异与地表温度相一致。 地图密度指数能较好刻画城市扩展范围及其发展强度，并与地表温度空间分布存在较好的对应关系。

A New Calibration Algorithm of Interferometric Parameters for Dual-antenna Airborne InSAR Systems

It is significant to calibrate interferometric parameters of dual-antenna airborne InSAR（Interferometric Synthetic Aperture Radar）systems for deriving accurate DEM (Digital Elevation Model) with large areas. A new outside calibration model considering phase offset, baseline length and baseline angle was proposed in order to calibrate interferometric parameters effectively, which was induced from the basic theory of DEM deriving from InSAR. And its solution scheme was designed. The outside calibration experiments were done with height control points measured by GPS to calibrate the dual-antenna airborne InSAR system researched independently by Institute of Electronics, Chinese Academy of Sciences. The accuracy of heights derived with calibrated interferometric parameters was calculated, as validated the proposed calibration model and its solution algorithm.