GravityPython: An Open-Source Pipeline for Inversion, Analysis, Assimilation, and Earth System Applications

Next-generation satellite gravity missions such as NGGM and MAGIC are expected to provide unprecedented observations of Earth’s time-variable gravity field, offering transformative opportunities for understanding mass transport processes in the global water cycle, solid Earth, cryosphere, and ocean systems. Fully exploiting the scientific potential of these missions requires an end‑to‑end workflow that ensures methodological consistency from raw sensor data to geophysically meaningful products. Addressing this need, we present a new integrated, open-source scientific platform developed in Python and publicly available on GitHub [1]. The platform consolidates processing steps across multiple levels of gravity field data, enabling researchers to seamlessly transition from Level‑1B observations to high‑level geophysical applications.

The platform is built upon a modular architecture that incorporates four core components.

(1) PyHawk provides a flexible and transparent environment for inverting GRACE/FO and future-mission Level‑1B measurements into time-variable gravity field solutions. It implements state-of-the-art dynamic orbit determination, variational inversion, and regularization strategies, designed to be easily extendable for upcoming mission concepts.

(2) SaGEA enables systematic post‑processing of Level‑2 spherical harmonic solutions, including filtering, destriping, stochastic error characterization, and advanced signal separation techniques to isolate hydrological, cryospheric, and oceanic mass variations.

(3) PyGLDA incorporates these gravity-derived Level‑3 products into a hydrological model through a global sequential data assimilation system capable of handling computational load at high resolution. This component provides improved estimates of terrestrial water storage anomalies and their subcomponents (soil moisture, groundwater, snow), offering new opportunities for hydrological analysis, drought monitoring, and water resource assessment.

(4) SaGEA‑Fluid computes a wide range of geophysical corrections driven by atmospheric, oceanic, hydrological, and cryospheric mass redistributions, including self‑attraction and loading (SAL), geocenter motion, and Earth orientation parameter (EOP) variations. These forward-model products ensure physically consistent comparisons between models and observations.

The integration of these modules into a single platform allows for a coherent and reproducible processing chain spanning mission‑level data to application‑ready geophysical outputs. Initial experiments demonstrate consistent agreement between satellite-derived mass variations and hydrological assimilation results, highlighting the platform’s potential for cross‑domain scientific studies. The system is under active development, with planned extensions including a fully customizable numerical mission simulator to support the design and performance assessment of next‑generation gravity missions. Overall, this platform offers a community-driven, open, and extensible foundation for advancing Earth system studies with current and future satellite gravimetry missions. It aims to enhance transparency, reproducibility, and scientific collaboration in preparation for the upcoming era of high-resolution, high-accuracy gravity field observations.

References

[1] https://github.com/NCSGgroup; https://github.com/AAUGeodesyGroup/PyGLDA