Next-Generation Gravity Missions: Sino-European Numerical Simulation Comparison Exercise

Abstract

Temporal gravity retrieval simulation results of a future Bender-type double pair mission concept, performed by five processing centers of a Sino-European study team, have been inter-compared and assessed. They were computed in a synthetic closed-loop simulation world by five independent software systems applying different gravity retrieval methods, but were based on jointly defined mission scenarios. The inter-comparison showed that the results achieved a quite similar performance. Exemplarily, the root mean square (RMS) deviations of global equivalent water height fields from their true reference, resolved up to degree and order 30 of a 9-day solution, vary in the order of 10% of the target signal. Also, co-estimated independent daily gravity fields up to degree and order 15, which have been co-estimated by all processing centers, do not show large differences among each other. This positive result is an important pre-requisite and basis for future joint activities towards the realization of next-generation gravity missions.

The Temporal Improvement of Earth's Mass Transport Estimated by Coupling GRACE‐FO With a Chinese Polar Gravity Satellite Mission

“…In this study, the input models used in the “True world” and “Reference world” are consistent with those of Pail et al. (2019). In the “True world,” the input models are set as GOCO05s, ESM AOHIS models, and EOT11a, respectively.…”

“…Different input models (i.e., the static gravity field model, temporal gravity field model, and ocean tide model) simulate the background forces during the orbital integration. The input models used in the "true world" and "reference world" are consistent with those of Pail et al (2019). In the "true world," the input models are set as GOCO05s, Earth System Model (ESM) AOHIS models, and EOT11a, respectively.…”

“…The noise of ACC is from that of Pail et al. (2019). Expressly, the measurement bandwidth assumes ACC noise level as 10 −11 m/s 2 /Hz 1/2 from along‐track and radial directions.…”

“…The noise level of KBR and LRI for a frequency band lower than 10 −2 Hz is assumed as 2 × 10 −7 m/s and 8 × 10 −8 m/s, respectively. The noise of ACC is from that of Pail et al (2019). Expressly, the measurement bandwidth assumes ACC noise level as 10 −11 m/s 2 /Hz 1/2 from along-track and radial directions.…”

“…Although GRACE and GRACE‐FO are capable of retrieving the mass transport on the Earth's surface with high temporal resolution (∼30 days, monthly solutions) and spatial resolution (∼300 km × 300 km), they still have some shortcomings, for example, the north‐south stripes (Swenson & Wahr, 2006), the signal distortion and leakage (Kusche et al., 2009), especially at the areas close to the sea‐land boundary. Up to date, more efforts are made to propose novel concepts of future satellite gravity missions with more advanced constellations to derive mass transport with high spatiotemporal resolution, that is, the Next Generation Gravity Mission (e.g., Pail et al., 2018; NG2 Team, 2011), the Earth System Mass Transport Mission (e.motion) (Panet et al., 2013), e 2 .motion (Gruber et al., 2014), the GRadiométrie à Interféromètres quantiques Corrélés pour l'Espace (GRICE) mission (Leveque et al., 2018), a mass variation observing system by high‐low inter‐satellite links (MOBILE) mission (Hauk & Pail, 2019), a Satellite Mission Concept Using Cold Atom Interferometry for Measuring the Earth Gravity Field (MOCASS) mission (Migliaccio et al., 2019), an ICARUS (International Cooperation for Animal Research Using Space) payload system on a future polar‐orbiting GRACE‐like (GRACE‐I) mission (Flechtner, 2020), the GRAvity observations by Vertical Laser ranging (GRAVL) mission (Woodwark et al., 2020), the Mass And Reference Variations for Earth Lookout mission (Lemoine & Mandea, 2020), the Mass‐change and geosciences International Constellation (MAGIC) mission (Svehla, 2021), the Mass Change Designated Observable (MCDO) Study (Wiese et al., 2022), and so on. Of all the aforementioned studies for future gravity satellite missions mentioned above, the GRACE‐I and MAGIC missions are ongoing phase A studies, and MCDO is in the pre‐formulation phase, which has a tentative launch date.…”