## 4 Results and Discussion
### Horizontal Displacement and Amplitude Extraction Analysis
Figure 7: **(a)** Power profile of the WGC obtained from working base point S1 and selection of monitoring points. The red triangle denotes the monitoring point. The relative height of the building in the left figure is relative to working base point S1. Point A in the right figure is at the top of the building, with a height of 447 m relative to working base point S2. Point B is 300 m high relative to working base point S2. **(b)** Ground view of the WGC from the location of the IBIS-S-2 system. displacement amplitude of the roof of the WGC in the north-south direction during the monitoring period is 18.84 mm. For the east-west direction, the maximum negative and positive horizontal displacements of the roof are 7.10 and 8.84 mm, respectively, and the maximum east-west direction displacement amplitude of the roof is 15.94 mm. The displacement monitoring accuracies in the north-south and east-west directions at the top of the building are 0.15 and 0.17 mm, respectively. Figure 9 shows the horizontal displacement time series in the north-south and east-west directions at the building height of 300 m during the monitoring period. The maximum negative and positive horizontal displacements in the north-south direction at the building height of 300 m are 6.99 and 7.74 mm, respectively, and the maximum horizontal displacement amplitude is 14.73 mm. For the east-west direction, the maximum negative and positive horizontal displacements are 4.94 and 7.30 mm respectively, and the maximum horizontal displacement amplitude reaches 12.24 mm. At the building height of 300 m, the monitoring accuracies of displacement in the north-south and east-west directions are 0.09 and 0.10 mm, respectively. The maximum horizontal displacement amplitudes at the building height of 300 m in the north-south and east-west directions are 4.11 and 3.70 mm less than that compared with the roof of the building, respectively. The comparative analysis of Figures 6 and 7 shows that the displacement change of the building is relatively large before 7 July 2017, whereas the subsequent displacement steadily changes. The original displacement curve obtained based on radar data immensely fluctuated and was accompanied by many burr points. After denoising the original displacement curve through wavelet analysis [41; 42], the burr phenomenon in the original displacement curve was basically eliminated, and the displacement curve became smooth, as shown in Figures 8 and 9 (black line). However, the displacement curve after denoising still exhibited a certain fluctuation, and the displacement curve at the building height of 447 m was more obvious than that at the building height of 300 m. This phenomenon may be attributed to the serious effect of noise caused by construction vibration, instrument system error, external environment, and other factors on the radar signal during the monitoring period. Although most of the noises were  
Figure 8: IBIS-S-derived horizontal displacement time series in east–west **(a)** and north–south **(b)** directions at 447 m height of the WGC. The red line denotes the displacement time series without denoising, and the black line represents the displacement time series after denoising. removed through wavelet analysis, a slight vibration still existed in the building itself when it swung because of the influences of construction vibration and other factors. Therefore, the displacement curve after wavelet denoising still had a small fluctuation, and this part of fluctuation may be caused by the slight vibration of the building itself when it swung. GB-RAR can realize high-accuracy continuous dynamic monitoring of super high-rise buildings, and the monitoring accuracy can reach submillimeter level. However, the monitoring accuracy gradually decreased with the increase in floors.