The CSES global geomagnetic field model (CGGM): an IGRF-type global geomagnetic field model based on data from the China Seismo-Electromagnetic Satellite

Abstract

Using magnetic field data from the China Seismo-Electromagnetic Satellite (CSES) mission, we derive a global geomagnetic field model, which we call the CSES Global Geomagnetic Field Model (CGGM). This model describes the Earth’s magnetic main field and its linear temporal evolution over the time period between March 2018 and September 2019. As the CSES mission was not originally designed for main field modelling, we carefully assess the ability of the CSES orbits and data to provide relevant data for such a purpose. A number of issues are identified, and an appropriate modelling approach is found to mitigate these. The resulting CGGM model appears to be of high enough quality, and it is next used as a parent model to produce a main field model extrapolated to epoch 2020.0, which was eventually submitted on October 1, 2019 as one of the IGRF-13 2020 candidate models. This CGGM candidate model, the first ever produced by a Chinese-led team, is also the only one relying on a data set completely independent from that used by all other candidate models. A successful validation of this candidate model is performed by comparison with the final (now published) IGRF-13 2020 model and all other candidate models. Comparisons of the secular variation predicted by the CGGM parent model with the final IGRF-13 2020–2025 predictive secular variation also reveal a remarkable agreement. This shows that, despite their current limitations, CSES magnetic data can already be used to produce useful IGRF 2020 and 2020–2025 secular variation candidate models to contribute to the official IGRF-13 2020 and predictive secular variation models for the coming 2020–2025 time period. These very encouraging results show that additional efforts to improve the CSES magnetic data quality could make these data very useful for long-term monitoring of the main field and possibly other magnetic field sources, in complement to the data provided by missions such as the ESA Swarm mission.

Evaluation of candidate models for the 13th generation International Geomagnetic Reference Field

“…The IGRF-13 candidate models were built primarily using data recorded by the European Space Agency (ESA) Swarm satellite mission (2013-present) and ground magnetic observatories. One team used the China Earthquake Administration's CSES mission (Shen et al 2018) exclusively for its candidate model (Yang et al 2020). Some teams built parent models spanning longer time intervals, which additionally made use of data from the CHAMP (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010), Ørsted (1999-2013), and SAC-C (2000)(2001)(2002)(2003)(2004) missions.…”

“…Several teams built parent models covering the full Swarm satellite mission era (November 2013 to present) (Brown et al 2020;Rother et al 2020;Vigneron et al 2020). Other teams built dedicated main field candidate models for each of the epochs requested by the call, thus using data within smaller time windows centered on 2015.0, or immediately preceding 2020.0 (Pavón-Carrasco et al 2020;Yang et al 2020;Alken et al 2020a;Petrov and Bondar 2020), which required less complex parameterization in time. Some teams co-estimated a low-degree external field model representing magnetospheric sources (Brown et al 2020;Yang et al 2020;Pavón-Carrasco et al 2020;Rother et al 2020;Ropp et al 2020;Huder et al 2020;Sabaka et al 2020;Vigneron et al 2020).…”

Observing Earth’s magnetic environment with the GRACE-FO mission

“…A special consideration of data from DMSP and ESA's CryoSat-2 was taken to enhance the data availability between the re-entry of CHAMP in 2010 and the launch of the Swarm mission in 2013 (e.g., Alken et al 2020a;Finlay et al 2020). Data from the recently launched CSES mission of the China Earthquake Administration have provided a candidate model for the International Geomagnetic Reference Field (IGRF-13) (Alken et al 2020b;Yang et al 2020).…”

CSES High Precision Magnetometer Data Products and Example Study of an Intense Geomagnetic Storm

“…Using HPM data, we could also construct an analog to the Dst index, which displays a dynamics very close to that of the official Dst index Generally, the preliminary analysis of CSES magnetic field data thus shows that the HPM package already provides data of good quality and high scientific potential. As a matter of fact, it is worth finally pointing out that a main field model has already been built using these CSES data (Yang et al, 2021), which successfully contributed to the latest release of the International Geomagnetic Reference Field model (Alken et al, 2021). We are now looking forward to many more such useful applications of the CSES HPM data.…”