## 5 Discussion  
To evaluate the permafrost deformation in the northern QTP, we compared other studies that are shown in Table 6.  
[PERSON] et al. [66] used the PSI technique with Envisat datasets to reveal the ground deformation in Beiluhe. The result shows that the average deformation from 2003 to 2007 was \(-\)20\(-\)3 mm/year. [PERSON] [67] used multisource datasets (ALOS and Envisat) based on the IPTA and SABS techniques to illuminate the displacement of permafrost in Beiluhe. The result shows that the average displacement is \(-\)20\(-\)20 mm/year. [PERSON] et al. [28] found that the average deformation of permafrost in Beiluhe is \(-\)25\(-\)10 mm/year by using the SBAS method with ALOS data. From 2014 to 2020, [PERSON] et al. and [PERSON] et al. [68] used the MT-InSAR method to research the deformation of permafrost in the QTP. [PERSON] et al. [69] found that the average deformation in Yangbajin ranged from \(-\)30 to 10 mm/year from 2014 to 2015. [PERSON] et al. [54] used Sentinel-1 data based on NSBAS to reveal the deformation of the whole QTP. The result shows that the average deformation rate is \(-\)20\(-\)20 mm/year. [PERSON] et al. [8] used three different sensor datasets (ERS-1, Envisat and Sentinel-1) to reveal the freeze-thaw cycle of permafrost in Wudaoliang and Tuouohe from 1997 to 2008. The result shows that the average deformation rate ranges from \(-\)20 to 10 mm/year. From the above related research, our results are consistent with the previous results. In addition, to evaluate the accuracy of the SBAS-InSAR results in this paper, we used leveling data from other researchers in the QTR [70]. The locations of the three leveling points are shown in Figure 8. The elevations of the three leveling points were collected on 9 January 2018, and 11 February 2018. The deformation results of 3 January 2018 and 8 February 2018, were extracted from 150-475 (Path-Frame) Sentinel-1 InSAR results. In order to ensure the accuracy, we convert the leveling results to the displacement of the LOS direction based on the radar incident angle. The comparison between the InSAR experiment results and the leveling results of A, B and C is shown in Table 7. Table 7 shows that the absolute errors of the leveling data and InSAR measurements at points A, B and C were 3.1, 5.7 and 6.8 mm, respectively, which were relatively small. Through a comparison with previous studies and leveling data, this paper provides a theoretical basis and data support for the study of permafrost evolution. However, there are some limitations in our study. First, there are some errors in the InSAR processing, such as orbit errors, unwrapping phase errors, residual topographic errors, and ERA5 APS correction errors. These errors may lead to incorrect permafrost deformation. Second, from 2010 to 2015, due to the lack of data, we have no ability to monitor the deformation of permafrost in the QTP during this period. In the future, we will \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Study Area** & **InSAR Method** & **SAR Dataset** & **Observation Time** &
\begin{tabular}{c} **Average Ground** \\ **Deformation Rate** \\ \end{tabular} & **Authors** \\ \hline Beiluhe & PSI & Envisat & 2003–2007 & \(-\)20\(-\)3 mm/year & [PERSON] et al. (2010) \\ Beiluhe & IPTA and SBAS & ALOS and Envisat & 2004–2010 & \(-\)20\(-\)20 mm/year & [PERSON] et al. (2012) \\ Beiluhe & SBAS & ALOS & 2007–2010 & \(-\)25\(-\)10 mm/year & [PERSON] et al. (2013) \\ Naqu-Lhasa & SBAS & Envisat and & 2003–2012 & \(-\)20\(-\)20 mm/year & [PERSON] et al. (2018) \\ Yangbajin & MTInSAR & TerraSAR-X & 2014–2015 & \(-\)30\(-\)10 mm/year & [PERSON] et al. (2017) \\ Wudaoliang- & MT-InSAR & Sentinel-1, Envisat & 1997–2018 & \(-\)20\(-\)10 mm/year & [PERSON] et al. (2019) \\ Tuotuohe & & and ERS-1 & & \\ Wudaoliang & StaMPS-InSAR & Sentinel-1 and & 2017–2018 & \(-\)12–7 mm/year & [PERSON] et al. (2020) \\ Golmud-Lhasa & NSBAS & Sentinel-1 & 2017–2020 & \(-\)20–20 mm/year & [PERSON] et al. (2021) \\ \hline \hline \end{tabular}
\end{table}