Analysis results of spatial distribution of the identified oscillation centers. a: positions of the oscillation centers (red dots). The background image is from the IRIS SJI 2832 Å data, which shows the solar atmosphere at the photospheric height. The white ellipse and dashed line indicate a defined umbral region for identifying the umbral flashes and the convergent interface, respectively. b: HMI magnetic field strength map. The black contour indicates the umbral-penumbral boundary obtained from the IRIS SJI 2832 Å image. c: distribution of the oscillation centers from the convergent interface. Each column represents a different observation date.