## 5 Conclusions  
In this study, we carry out four experiments to investigate mass variations caused by degree one terms, SLR-based C\({}_{20}\), and C\({}_{30}\) estimates corresponding, respectively, to GRACE RL05 and RL06  
data published by CSR, GFZ, and JPL over the GrIS and the AIS. We report that the trend of mass change caused by degree one terms corresponding to GRACE RL06 data in absolute value is 2.5 times larger than that for GRACE RL05 data. The annual amplitude of mass change caused by degree one terms corresponding to GRACE RL06 data is more than 30% larger than that over each ice sheet for GRACE RL05 data. Mass variations caused by SLR-based \(C_{20}\) estimates from TN07, TN11, and GFZ exhibit better agreement on the annual amplitude, with relatively smaller annual amplitude revealed by those corresponding to TN14. The linear trend of mass variations derived from \(C_{20}\) estimates in TN14 is more negative, with its absolute value being more than 50% larger than those from \(C_{20}\) estimates provided by TN07, TN11, and GFZ over each ice sheet. The mass change time series caused by SLR-based \(C_{30}\) estimates in TN14 exhibit an annual amplitude which is 23% smaller than those derived from GRACE RL05 and RL06 data. The mean value of linear trend of mass change time series caused by SLR-based \(C_{30}\) in TN14 in absolute value is almost two times larger than those from GRACE RL06 data during the time span from March 2012 to July 2016. The combination of degree one terms, SLR-based \(C_{20}\), and \(C_{30}\) estimates corresponding to TN14 modifies the trend of mass variations over the GrIS and the AIS by \(-2.4\) and \(8.0\) Gt/yr, respectively, during the period from August 2002 to July 2016, compared to that corresponding to TN11. Our study demonstrates that these low degree terms have significantly increased impacts on mass variations over polar ice sheets. Compared with GRACE RL05 data, improvements can be seen in these consistent linear trends of mass variations computed by the combination of these low degree terms corresponding to GRACE RL06 over the AIS during the period from August 2002 to July 2016. This study suggests that reliable low degree spherical harmonic coefficients are crucial for the scientific applications of GRACE/GRACE-FO gravimetry data. [PERSON] conceptualized the experiments. She also performed the analysis and wrote the manuscripts. [PERSON] helped with improving the design of the experiments, and contributed to the analysis of the results. [PERSON], [PERSON], and [PERSON] provided useful comments and helped polish the manuscript. All authors have read and agreed to the published version of the manuscript. This research is funded by the National Key R&D Program of China, grant number 2018 YFC1503503, and the National Natural Science Foundation of China, grant number 41804014, 41931074, and 41974040. It is also partially supported by National Key Research & Development Program of China (2017 YFA0603103) and Strategic Priority Research Program of the Chinese Academy of Sciences (XDA19070302). [PERSON] would like to thank the platform support from the National Precise Gravity Measurement Facility. [PERSON] and [PERSON] give thanks for the administrative help from the Center for Gravitational Experiments, Huazhong University of Science and Technology. All the authors thank the three anonymous reviewers for their constructive comments which led to the improvement of the manuscript. In this study, GRACE-determined C\({}_{30}\) data products are from NASA via CSR, GFZ, and JPL, which can be accessed at [[http://podac.jpl.nasa.gov/grace](http://podac.jpl.nasa.gov/grace)]([http://podac.jpl.nasa.gov/grace](http://podac.jpl.nasa.gov/grace)) and [[http://isdc.gz-potsdam.de/grace](http://isdc.gz-potsdam.de/grace)]([http://isdc.gz-potsdam.de/grace](http://isdc.gz-potsdam.de/grace)).