@article{LesurWardinskiBaerenzungetal.2017,
  author    = {Lesur, Vincent and Wardinski, Ingo and B{\"a}renzung, Julien and Holschneider, Matthias},
  title     = {On the frequency spectra of the core magnetic field Gauss coefficients},
  series = {Physics of the earth and planetary interiors},
  volume    = {276},
  journal   = {Physics of the earth and planetary interiors},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0031-9201},
  doi       = {10.1016/j.pepi.2017.05.017},
  pages     = {145 -- 158},
  year      = {2017},
  abstract  = {From monthly mean observatory data spanning 1957-2014, geomagnetic field secular variation values were calculated by annual differences. Estimates of the spherical harmonic Gauss coefficients of the core field secular variation were then derived by applying a correlation based modelling. Finally, a Fourier transform was applied to the time series of the Gauss coefficients. This process led to reliable temporal spectra of the Gauss coefficients up to spherical harmonic degree 5 or 6, and down to periods as short as 1 or 2 years depending on the coefficient. We observed that a k(-2) slope, where k is the frequency, is an acceptable approximation for these spectra, with possibly an exception for the dipole field. The monthly estimates of the core field secular variation at the observatory sites also show that large and rapid variations of the latter happen. This is an indication that geomagnetic jerks are frequent phenomena and that significant secular variation signals at short time scales - i.e. less than 2 years, could still be extracted from data to reveal an unexplored part of the core dynamics.},
  language  = {en}
}
@article{StolleMichaelisXiongetal.2021,
  author    = {Stolle, Claudia and Michaelis, Ingo and Xiong, Chao and Rother, Martin and Usbeck, Thomas and Yamazaki, Yosuke and Rauberg, Jan and Styp-Rekowski, Kevin},
  title     = {Observing earth's magnetic environment with the GRACE-FO mission},
  series = {Earth, planets and space : EPS},
  volume    = {73},
  journal   = {Earth, planets and space : EPS},
  number    = {1},
  publisher = {Springer},
  address   = {Heidelberg},
  issn      = {1880-5981},
  doi       = {10.1186/s40623-021-01364-w},
  pages     = {21},
  year      = {2021},
  abstract  = {The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission carries magnetometers that are dedicated to enhance the satellite's navigation. After appropriate calibration and characterisation of artificial magnetic disturbances, these observations are valuable assets to characterise the natural variability of Earth's magnetic field. We describe the data pre-processing, the calibration, and characterisation strategy against a high-precision magnetic field model applied to the GRACE-FO magnetic data. During times of geomagnetic quiet conditions, the mean residual to the magnetic model is around 1 nT with standard deviations below 10 nT. The mean difference to data of ESA's Swarm mission, which is dedicated to monitor the Earth's magnetic field, is mainly within +/- 10 nT during conjunctions. The performance of GRACE-FO magnetic data is further discussed on selected scientific examples. During a magnetic storm event in August 2018, GRACE-FO reveals the local time dependence of the magnetospheric ring current signature, which is in good agreement with results from a network of ground magnetic observations. Also, derived field-aligned currents (FACs) are applied to monitor auroral FACs that compare well in amplitude and statistical behaviour for local time, hemisphere, and solar wind conditions to approved earlier findings from other missions including Swarm. On a case event, it is demonstrated that the dual-satellite constellation of GRACE-FO is most suitable to derive the persistence of auroral FACs with scale lengths of 180 km or longer. Due to a relatively larger noise level compared to dedicated magnetic missions, GRACE-FO is especially suitable for high-amplitude event studies. However, GRACE-FO is also sensitive to ionospheric signatures even below the noise level within statistical approaches. The combination with data of dedicated magnetic field missions and other missions carrying non-dedicated magnetometers greatly enhances related scientific perspectives.},
  language  = {en}
}
@article{BrownDonadiniNilssonetal.2015,
  author    = {Brown, Maxwell C. and Donadini, Fabio and Nilsson, Andreas and Panovska, Sanja and Frank, Ute and Korhonen, Kimmo and Schuberth, Maximilian and Korte, Monika and Constable, Catherine G.},
  title     = {GEOMAGIA50.v3: 2. A new paleomagnetic database for lake and marine sediments},
  series = {Earth, planets and space},
  volume    = {67},
  journal   = {Earth, planets and space},
  publisher = {Springer},
  address   = {Heidelberg},
  issn      = {1880-5981},
  doi       = {10.1186/s40623-015-0233-z},
  pages     = {19},
  year      = {2015},
  abstract  = {Background: GEOMAGIA50.v3 for sediments is a comprehensive online database providing access to published paleomagnetic, rock magnetic, and chronological data obtained from lake and marine sediments deposited over the past 50 ka. Its objective is to catalogue data that will improve our understanding of changes in the geomagnetic field, physical environments, and climate. Findings: GEOMAGIA50.v3 for sediments builds upon the structure of the pre-existing GEOMAGIA50 database for magnetic data from archeological and volcanic materials. A strong emphasis has been placed on the storage of geochronological data, and it is the first magnetic archive that includes comprehensive radiocarbon age data from sediments. The database will be updated as new sediment data become available. Conclusions: The web-based interface for the sediment database is located at http://geomagia.gfz-potsdam.de/geomagiav3/SDquery.php. This paper is a companion to Brown et al. (Earth Planets Space doi:10.1186/s40623-015-0232-0,2015) and describes the data types, structure, and functionality of the sediment database.},
  language  = {en}
}