CM6: a comprehensive geomagnetic field model derived from both CHAMP and Swarm satellite observations

Terence J Sabaka,Nils Olsen,Lars Tøffner-Clausen,Christopher C Finlay

doi:10.1186/s40623-020-01210-5

Terence J Sabaka, Nils Olsen + Show 2 more

Open Access

https://doi.org/10.1186/s40623-020-01210-5

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Abstract

From the launch of the Ørsted satellite in 1999, through the CHAMP mission from 2000 to 2010, and now with the Swarm constellation mission starting in 2013, satellite magnetometry has provided excellent monitoring of the near-Earth magnetic field regime. The advanced Comprehensive Inversion scheme has been applied to data before Swarm and to the Swarm data itself, but now for the first time to all the satellite data in this new era, culminating in the CM6 model. The highlights of this model include not only a continuous core magnetic field description over the entire time period 1999 to 2019.5 in good agreement with the CHAOS model series, but the addition of two new oceanic tidal magnetic sources: the larger lunar elliptic semi-diurnal constituent N_2 and the lunar diurnal constituent O_1. CM6 is also the parent model of the NASA/GSFC candidates for the DGRF2015 and IGRF2020 in response to the IGRF-13 call. This paper provides a full report on the development of CM6.

Highlights

The “modern era” of satellite magnetometry can be said to have been initiated with the launch of the Danish satellite SAC-C model (Ørsted) on 23 February, 1999, followed by the “CHAllenging Minisatellite Payload” (CHAMP) launched on 15 July, 2000 and flying for 10 years before its demise in September, 2010
For more than two decades the magnetic modeling group at the NASA/Goddard Space Flight Center (GSFC), in collaboration with the group at the Technical University of Denmark (DTU), developed a modeling approach known as the “Comprehensive Inversion” (CI) in which the majority of dominant magnetic signals detected in the near-Earth regime are parameterized and subsequently co-estimated to obtain optimal signal separation, while taking into account both random and systematic errors
With the recent work of Grayver and Olsen (2019), it is clear that combinations of CHAMP and Swarm measurements are beginning to resolve some weaker tidal constituents, such as the larger lunar elliptic semi-diurnal constituent N2 and the lunar diurnal constituent O1, and so these have been included in the CI parameterization

Summary

Introduction

The “modern era” of satellite magnetometry can be said to have been initiated with the launch of the Danish satellite Ørsted on 23 February, 1999 (still in orbit, but not collecting magnetic measurements since summer 2014), followed by the “CHAllenging Minisatellite Payload” (CHAMP) launched on 15 July, 2000 and flying for 10 years before its demise in September, 2010.

Results

Conclusion