【摘要】 利用GPS数据改正InSAR大气影响中,GPS站网的低空间密度是限制改正精度的一个主要因素.文中引入大气传输模型(ATM)来考虑大气状态在时间上的演化,并兼顾了风向的估计,把GPS-ZWD(GPS湿延迟)时间序列观测值转换为空间上分布比较稠密的GPS-ZWD网络,然后利用该稠密网络在空间上内插产生水汽延迟图,来更好地模拟InSAR影像获取时刻的水汽场,提高大气改正精度.实验结果表明,在研究地区有限的数据条件下(即只有6个GPS点的情况下),GPS+ATM算法在重现大气信号能力方面比单纯的使用影像获取时刻的GPS-ZWD数据要强,并且其对长波的大气误差去除更明显;用来做实验的三幅差分干涉图中,GPS+ATM算法对两幅以长波信号为主的干涉图中的大气影响分别降低了21.7%和22.6%,比仅使用SAR过境时刻GPS-ZWD数据时的结果分别改进了4.5%和8.7%.而对以短波信号为主的干涉图没有明显提高.更多还原

【Abstract】 It is usually believed that the sparse spatial resolution of GPS stations is a main limitation factor for improving correction accuracy when we use GPS-ZWD data to mitigate atmospheric effect in repeat-pass InSAR measurement.In this paper,a simple atmospheric transport model (ATM) is induced to consider a temporal evolution of atmospheric state,GPSZWD time series around SAR overpass time can be transformed into a spatially denser network of GPS-ZWD control points by using the ATM after wind velocity is estimated.The denser network of GPS-ZWD enable estimation of ZWD difference maps to match better atmospheric phase distortions observed in the InSAR data.The experimental data analysis from the three differential interferograms of Shanghai demonstrates GPS+ATM method can reproduce the atmospheric signal with stronger ability than the method only using the GPS-ZWD data recorded at the radar observation times,and the reduction for long-wavelength signal is much remarkable under the condition with limited data resources of research area (only six GPS station).After applying GPS +ATM algorithm,the global root mean square (RMS) atmospheric phase fluctuations of the two interferograms dominating by the long-wavelength signal,decrease by 21.7% and 22.6% respectively,with a improvement of 4.5% and 8.7% compared with the former method,but no improvement in another one dominating by the short-wavelength signal.更多还原