“…For the missing solutions within the missions, linear or spline interpolations are performed to fill these gaps, without proper justification, or constraining the uncertainties in these solutions. For the gap between the two missions, different approaches have been used to fill the missing data and reconstruct the gap, and can be summarized as follows: For the ice sheets, the independent mass balance changes were incorporated with GRACE (‐FO) observations to infer the status of the ice loss between 2017 and 2018 (Velicogna et al., 2020); For the land hydrology, where the most of the reconstruction studies focused on, the total water storage (TWS), which represents the sum of all storage compartments (snow water equivalent, surface water, soil water, groundwater, and ice) was reconstructed using Global Positioning Systems (GPS) (Rietbroek et al., 2014), or informed using hydroclimate predictors within statistical learning framework for the first mission (Li et al., 2020; Li, Wang, et al., 2019; Mo et al., 2022; Sun et al., 2021, 2020; Wang et al., 2021; Yang et al., 2021). Assimilating GRACE into land surface modeling (e.g., CLSM‐F2.5) is another approach to fill the gap in GRACE (‐FO) over land (Li, Rodell, Kumar, et al., 2019).…”