Objectives When the conventional time-series interferometric synthetic aperture radar (InSAR) technology is applied to the surface deformation monitoring of mining areas, it is difficult to fully reflect the surface deformation characteristics of the goaf due to the uneven distribution and small number of monitor‍ing points. In addition, distributed scatterers are seriously affected by the temporal and spatial incoher‍ence. Thus the corresponding phase optimizing operation is a key step in fusing distributed scatterers(DS) points into time-series InSAR analysis. The current constraints of phase space continuity in the phase optimization of distribut‍ed targets are insufficient.

Methods A phase optimization method based on the region growing algorithm is proposed. The detailed surface deformation information in complex environment could be obtained by optimizing phase in both time and spatial domain. The optimized phase of distributed scatter is evaluated qualitatively and quantitatively in Pan'an Lake area.

Results The proposed method and Sentinel-1 data are used to investigate the surface deformation of abandoned mining areas around Xuzhou from May 2018 to May 2020. Besides, the accuracy and reliability of this method are proved by continuously operating refer‍ence stations results and bedrock-exposed area.

Conclusions The result indicates that the meth‍od gives a good performance on reducing phase noise by two-dimensional phase optimization of distrib‍uted scatterers, which would be good for obtaining the surface deformation information in the abandoned mining areas.