Figure 1 GF-3 interferogram around Shanghai, China (20161114-20170310): (i) Time span:
116 days; Spatial baseline (orbital separation): 598 m; (ii) the long-wavelength parallel
fringes are caused by the uncertainties in satellite orbital positions; (iii) About two fringes are
observed in the area indicated by a red rectangle, implying c. 5.6 cm of subsidence (likely
caused by groundwater extraction) during the 116-day period.