## 5 Conclusions

Table 3: Overview of the detectability of geophysical signals by GRACE and MOCAST+. For MOCAST+, the comparison is relative to GRACE. d/o = degree and order; \(\lambda/2=\) half-wavelength of highest resolvable d/o. with respect to the possibility of identifying geophysical phenomena is summarized via the following improvements:  
* The monitoring of seasonal components of reservoirs, lakes, and glaciers with areas > 8000 km\({}^{2}\) and seasonal mass variations of 10 Gt: the estimate of the seasonal component allows for the retrieval of long-period trends with minor uncertainty;
* The sensitivity to deglaciation processes: in the case of Patagonian glaciers, the minimum rate observable with MOCAST+ amounts to 5 Gt/yr, an improvement compared to the GRACE observations, which detect a level of 10 Gt/yr;
* The spatial resolution for the long-term monitoring of hydrologic basins and lakes: considering the example of the Tibetan lakes, which gain about 10 Gt/yr, MOCAST+ after 1 year resolves the variation that GRACE resolves after two years; after 5 years, MOCAST+ can retrieve the signal up to degree 50 in the spherical harmonic expansion, whereas GRACE resolves this signal only up to degree 32. This research could be brought to the level SRL5, which is focalized on the end-to-end simulations. Our database and the strategy to assess the impact of the mission could be developed into a flexible tool, which could be used to assess the performance of the next generation of gravity-mission-concept choices. Conceptualization, T.P., C.B. and A.P. ; methodology, T.P., C.B. and A.P. ; software, T.P. and A.P. ; validation, T.P., C.B. and A.P. ; formal analysis, T.P. ; investigation, T.P., C.B. and A.P. ; resources, T.P. ; data curation, T.P. ; writing--original draft preparation, T.P. and C.B. ; writing--review and editing, T.P., C.B. and A.P. ; visualization, T.P. ; supervision, C.B. ; project administration, C.B. ; funding acquisition, C.B. All authors have read and agreed to the published version of the manuscript. The study presented in this paper was funded by the Italian Space Agency ASI (Agenzia Spaziale Italiana) under ASI Contract No. 2019-16-U.0 \"MOCAST+ MOnitoring mass variations by Cold Atom Sensors and Time measures\". We provide the simulated gravity fields employed for the sensitivity analysis in spherical harmonic coefficients. This database of simulated signals can be retrieved at [[https://doi.org/10.5281/zenodo.6838878](https://doi.org/10.5281/zenodo.6838878)]([https://doi.org/10.5281/zenodo.6838878](https://doi.org/10.5281/zenodo.6838878)) [32] (accessed on 15 July 2022). We acknowledge the contribution of the partners of the MOCAST+ ASI financed project: [PERSON] (1), [PERSON] (1), [PERSON] (2), [PERSON] (3), [PERSON] (4), [PERSON] (5), [PERSON] (1), [PERSON] (1), [PERSON] (1), [PERSON] (6) of the following instutions: (1) Politecnico di Milano, Department of Civil and Environmental Engineering, Milano, Italy; (2) The National Institute for Nuclear Physics, Florence, and AtomSensors srl, Florence, Italy; (3) University of Florence, Department of Physics and Astronomy, Florence, and LENS Laboratory, Florence, Italy; (4) The National Institute for Nuclear Physics, Genova, Italy; (5) Thales Alenia Space Italia, Turin, Italy; (6) Italian Space Agency (ASI), Rome, Italy. We thank four anonymous meticulous reviewers. The authors declare no conflict of interest.