提出一种结合子孔径相关测度的时序高相干点探测方法，首先对时序 SAR 影像进行谱分解获得子孔径视图，通过时序子孔径相关测度进行强散射点筛选，然后分别根据振幅离差和干涉相位空间相关性，对目标点进行相位稳定性分析，探测出既满足强散射且在时间序列上散射稳定的高相干点。利用改进的点探测方法和短基线INSAR技术，对北京2003-2009年间40景ASAR影像进行相位建模，获取地面沉降时空分布特征，分析典型地物时序沉降过程，研究北京地面沉降与地下水开采关系。结果表明：相比已有方法，本文结合子孔径相关测度的高相干点探测结果更准确可靠；利用本文点探测方法反演的历史累积沉降信息，与水准结果一致，平均速率之差在3.69 mm/a以内，中误差为1.36 mm/a；研究区地面沉降最大速率达92.25 mm/a，空间不均匀分布明显，地面沉降量与地下水开采量呈分段的非线性相关。

Identification of stable pointwise target is an important procedure in multi temporal multi-temporal INSAR analysis and application in monitoring regional surface deformation. The accurate identification result helps to improve the land subsidence inversion precision. Various methods for pointwise target detection have been proposed during the past two decades from different respective. The methods can be divided into some main categories according to the criteria for coherence point selection, such as amplitude dispersion index D_A, signalto-Clutter ratio and phase stability. The D_A method performs a time series analysis on amplitude instead of phase, and reflects the stability of series amplitude. The advantage of coherence point selection by phase stability can identify some special objects with a stable phase, which further increases the density of the stable pointwise target points, but ignores the highly scattering reflection characteristics of the coherent point. The existing methods take insufficient account of the overall features of stable pointwise targets. For ensuring stable scattering mechanism and temporal stability of pointwise target, an improved method with subaperture correlation was proposed in this paper. First, the subaperture correlation properties IHP of SAR images were obtained by spectral decomposition. Then the stability of targets is evaluated based on series two-aperture spectral coherence, by which the coherence points with high scattering could be identified and detect as PSC1. The D_A threshold is utilized as the second criterion, which means any pixel in PSC1 with amplitude dispersion less than 0.4 can be determined as PSC2Then phase stability analysis was carried out to screen out the true stable points from PSC2 with the Characteristics of high scattering mechanism and temporal stability. The experiments of stable pointwise target detection were performed using 33 high resolution SAR images collected by the TerraSAR X-band radar sensor covering Beijing. The detection results demonstrated that the improved method can detect more accurate and reliable pointwise targets than those identified by traditional methodsTo further confirm the effectiveness of the proposed method, the small subset INSAR technique based on the proposed coherence point detection method was adopted to retrieve the ground deformation by 40 scenes dataset acquired from 2003 to 2009 in Beijing. The vertical surface displacement rates during this period was validated by the leveling observations, with RMSE=1.36 mm/a, indicating two types of subsidence matched very well. The maximum subsidence rate of Beijing in investigated area has reached -92.25 mm/a, with an obvious uneven spatial distribution. Subaperture correlation is sensitivity to the high scattering body and can ensure stable scattering mechanism and temporal stability of pointwise target. Both coherence point detection results and the primary surface deformation proved the effectiveness of the proposed method. The deformation result during 2003-2009 has undergone severe land subsidence with high spatial aggregation characteristic, and the regional subsidence and the groundwater exploitation reveal good corresponding relationship, the more exploitation, the higher deformation rate.