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A Dynamical Prospective on Interannual Geomagnetic Field Changes

Abstract

Geomagnetic observations from satellites have highlighted interannual variations in the rate of change of the magnetic field originating from Earth’s core. Downward continued to the core surface, these variations primarily show up in the equatorial belt. First, we recall the main characteristics of these patterns, addressing their spatio-temporal resolution, as seen from field models. We then review the several dynamical frameworks proposed so far to understand and model these observations, which populate the frequency spectrum on time scales close to the Alfvén time \(\tau _A\approx 2\) yr, much shorter than the vortex turnover time \(\tau _U\approx 150\) yr in Earth’s core. Magnetic–Archimedes–Coriolis (MAC) waves in a stratified layer below the core surface constitute a first possibility in the case of a sub-adiabatic heat flux at the top of the core. Their period may reach the interannual range for a layer thickness less than \(\approx 30\) km, for a buoyancy frequency of the order of the Earth’s rotation rate. An alternative has been proposed in a context where the Coriolis force dominates the momentum balance, rendering transient motions almost invariant along the rotation axis (quasi-geostrophy, QG). Torsional Alfvén waves, consisting of axisymmetric QG motions, operate at periods similar to the Alfvén time, but are not sufficient to explain the interannual field changes, which require non-axisymmetric motions. QG Alfvén waves (involving the Coriolis and magnetic forces) constitute another possibility, with inertia playing an important role. They have been detected in the latest generation of geodynamo simulations, propagating in a ubiquitous manner at a speed slightly less than the Alfvén velocity. They are localized in longitude and as a result their description requires high azimuthal wavenumber. But the branch of QG waves with large extent in azimuth is also worth considering, as it reaches interannual periods as their radial wavenumber is increased. The excitation of such high-frequency dynamics is discussed with respect to the temporal spectrum of the core field, which presents a slope \(\sim f^{-4}\) for periods approximately between \(\tau _A\) and \(\tau _U\). We finally summarize the main geophysical implications of the existence of this interannual dynamics on core and lower mantle structure, properties, and dynamics.

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References

  1. Abarca del Rio R, Gambis D, Salstein DA (2000) Interannual signals in length of day and atmospheric angular momentum. Annales Geophysicae 18(3), 347–364, DOI: https://doi.org/10.1007/s00585-000-0347-9

    Article  Google Scholar 

  2. Alexandrescu M, Gibert D, Hulot G, Le Mouël JL, Saracco G (1996) Worldwide wavelet analysis of geomagnetic jerks. J Geophys Res Solid Earth 101(B10):21975–21994. https://doi.org/10.1029/96JB01648

  3. Aubert J (2014) Earth’s core internal dynamics 1840–2010 imaged by inverse geodynamo modelling. Geophys J Int 197(3):1321–1334

  4. Aubert J (2018) Geomagnetic acceleration and rapid hydromagnetic wave dynamics in advanced numerical simulations of the geodynamo. Geophys J Int 214:531–547, DOI: 10.1093/gji/ggy161

    Article  Google Scholar 

  5. Aubert J (2019) Approaching Earth’s core conditions in high-resolution geodynamo simulations. Geophys J Int 219(Supplement\_1):S137–S151, https://doi.org/10.1093/gji/ggz232

  6. Aubert J (2020) Recent geomagnetic variations and the force balance in Earth’s core. Geophys J Int 221(1):378–393. https://doi.org/10.1093/gji/ggaa007

  7. Aubert J, Finlay CC (2019) Geomagnetic jerks and rapid hydromagnetic waves focusing at Earth’s core surface. Nature Geosci 12(5):393–398

  8. Aubert J, Gillet N (2021) The interplay of fast waves and slow convection in geodynamo simulations nearing Earth’s core conditions. Geophys J Int 225(3):1854–1873

  9. Aubert J, Finlay CC, Fournier A (2013) Bottom-up control of geomagnetic secular variation by the Earth’s inner core. Nature 502(7470):219–223

  10. Aubert J, Gastine T, Fournier A (2017) Spherical convective dynamos in the rapidly rotating asymptotic regime. J Fluid Mech 813:558–593

    Article  Google Scholar 

  11. Bardsley OP (2018) Could hydrodynamic Rossby waves explain the westward drift? Proc R Soc A Math Phys Eng Sci 474(2213). https://doi.org/10.1098/rspa.2018.0119

  12. Becker JM, Salmon R (1997) Eddy formation on a continental slope. Journal of marine research 55(2):181–200

    Article  Google Scholar 

  13. Bergman MI (1993) Magnetic Rossby waves in a stably stratified layer near the surface of the Earth’s outer core. Geophys Astrophys Fluid Dyn 68(1–4):151–176. https://doi.org/10.1080/03091929308203566

  14. Bouffard M, Choblet G, Labrosse S, Wicht J (2019) Chemical convection and stratification in the Earth’s outer core. Front Earth Sci 7:99. https://doi.org/10.3389/feart.2019.00099

  15. Bouligand C, Gillet N, Jault D, Schaeffer N, Fournier A, Aubert J (2016) Frequency spectrum of the geomagnetic field harmonic coefficients from dynamo simulations. Geophys J Int 207(2), 1142–1157

    Article  Google Scholar 

  16. Braginsky SI (1967) Magnetic waves in the Earth’s core. Geomag Aeron 7:851–859

  17. Braginsky SI (1970) Torsional magnetohydrodynamic vibrations in the Earth’s core and variations in day length. Geomag Aeron 10:1–8

    Google Scholar 

  18. Braginsky SI (1984) Short-period geomagnetic secular variation. Geophys Astrophys Fluid Dyn 30:1–78

    Article  Google Scholar 

  19. Braginsky SI (1993) MAC-oscillations of the hidden ocean of the core. J geomag geoelec 45(11–12):1517–1538

    Article  Google Scholar 

  20. Braginsky SI (1998) Magnetic Rossby waves in the stratified ocean of the core, and topographic core-mantle coupling. Earth, planets and space 50:641–649

    Article  Google Scholar 

  21. Brodholt J, Badro J (2017) Composition of the low seismic velocity E’ layer at the top of Earth’s core. Geophys Res Lett 44:8303–8310

    Article  Google Scholar 

  22. Brown W, Mound J, Livermore P (2013) Jerks abound: An analysis of geomagnetic observatory data from 1957 to 2008. Phys Earth Planet Int 223:62–76, DOI: https://doi.org/10.1016/j.pepi.2013.06.001

    Article  Google Scholar 

  23. Buffett B (2014) Geomagnetic fluctuations reveal stable stratification at the top of the Earth’s core. Nature 507:484–487. https://doi.org/10.1038/nature13122

  24. Buffett B, Matsui H (2015) A power spectrum for the geomagnetic dipole moment. Earth Planet Sc Lett 411:20–26

    Article  Google Scholar 

  25. Buffett B, Matsui H (2019) Equatorially trapped waves in Earth’s core. Geophys J Int 218(2):1210–1225

    Article  Google Scholar 

  26. Buffett B, Knezek N, Holme R (2016) Evidence for MAC waves at the top of Earth’s core and implications for variations in length of day. Geophys J Int 204(3), 1789–1800

    Article  Google Scholar 

  27. Buffett BA (2010) Tidal dissipation and the strength of the Earth’s internal magnetic field. Nature 468(7326):952–954. https://doi.org/10.1038/nature09643

  28. Buffett BA, Knezek N (2018) Stochastic generation of MAC waves and implications for convection in Earth’s core. Geophys J Int 212:1523–1535

  29. Buffett BA, Mound J, Jackson A (2009) Inversion of torsional oscillations for the structure and dynamics of Earth’s core. Geophys J Int 177(3):878–890. https://doi.org/10.1111/j.1365-246X.2009.04129.x

  30. Buffett BA, King EM, Matsui H (2014) A physical interpretation of stochastic models for fluctuations in the Earth’s dipole field. Geophys J Int 198(1), 597–608

    Article  Google Scholar 

  31. Busse FH (1975) A model of the geodynamo. Geophys J Int 42(2), 437–459, DOI: https://doi.org/10.1111/j.1365-246X.1975.tb05871.x

    Article  Google Scholar 

  32. Busse FH (1976) Generation of planetary magnetism by convection. Phys Earth Planet Int 12(4), 350–358, DOI: 10.1016/0031-9201(76)90030-3

    Article  Google Scholar 

  33. Canet E, Fournier A, Jault D (2009) Forward and adjoint quasi-geostrophic models of the geomagnetic secular variation. J Geophys Res 114:B11,101, DOI: 10.1029/2008JB006189

    Article  Google Scholar 

  34. Canet E, Finlay CC, Fournier A (2014) Hydromagnetic quasi-geostrophic modes in rapidly rotating planetary cores. Phys Earth Planet Int 229(Supplement C):1–15. https://doi.org/10.1016/j.pepi.2013.12.006

  35. Chao BF, Chung W, Shih Z, Hsieh Y (2014) Earth’s rotation variations: a wavelet analysis. Terra Nova 26(4), 260–264

    Article  Google Scholar 

  36. Chi-Durán R, Avery MS, Knezek N, Buffett BA (2020) Decomposition of geomagnetic secular acceleration into traveling waves using complex empirical orthogonal functions. Geophys Res Lett, p e2020GL087940

  37. Christensen U, Wardinski I, Lesur V (2012) Timescales of geomagnetic secular acceleration in satellite field models and geodynamo models. Geophys J Int 190(1), 243–254

    Article  Google Scholar 

  38. Christensen UR, Aubert J, Hulot G (2010) Conditions for earth-like geodynamo models. Earth Planet Sc Lett 296(3–4), 487–496

    Article  Google Scholar 

  39. Chulliat A, Maus S (2014) Geomagnetic secular acceleration, jerks, and a localized standing wave at the core surface from 2000 to 2010. J Geophys Res: Solid Earth 119(3), 1531–1543

    Article  Google Scholar 

  40. Chulliat A, Alken P, Maus S (2015) Fast equatorial waves propagating at the top of the Earth’s core. Geophys Res Lett 42(9):3321–3329

    Article  Google Scholar 

  41. De Michelis P, Cafarella L, Meloni A (1998) Worldwide character of the 1991 geomagnetic jerk. Geophys Res Lett 25(3), 377–380, doi: 10.1029/98GL00001

    Article  Google Scholar 

  42. De Santis A, Barraclough D, Tozzi R (2003) Spatial and temporal spectra of the geomagnetic field and their scaling properties. Phys Earth Planet Int 135(2), 125–134

    Article  Google Scholar 

  43. Domingos J, Pais MA, Jault D, Mandea M (2019) Temporal resolution of internal magnetic field modes from satellite data. Earth, Planets and Space 71(1), 1–17

    Article  Google Scholar 

  44. Duan P, Huang C (2020) Intradecadal variations in length of day and their correspondence with geomagnetic jerks. Nature communications 11(1):1–8

    Article  Google Scholar 

  45. Dumberry M, More C (2020) Weak magnetic field changes over the pacific due to high conductance in lowermost mantle. Nature Geoscience 13(7), 516–520

    Article  Google Scholar 

  46. Dziewonski AM, Anderson DL (1981) Preliminary reference Earth model. Phys Earth Planet Int 25(4), 297–356

    Article  Google Scholar 

  47. Eymin C, Hulot G (2005) On core surface flows inferred from satellite magnetic data. Phys Earth Planet Int 152(3), 200–220, doi: 10.1016/j.pepi.2005.06.009

    Article  Google Scholar 

  48. Fearn D (1994) Magnetic instabilities in rapidly rotating systems. In: Proctor MRE, Matthews PC, Rucklidge AM (eds) Solar and planetary dynamos. Publications of the Newton Institute, Cambridge University Press, pp 59–68. https://doi.org/10.1017/CBO9780511662874.009

  49. Fearn DR (1989) Differential rotation and thermal convection in a rapidly rotating hydromagnetic system. Geophys Astrophys Fluid Dyn 49(1–4), 173–193, DOI: 10.1080/03091928908243471

    Article  Google Scholar 

  50. Finlay C, Dumberry M, Chulliat A, Pais M (2010) Short timescale core dynamics: theory and observations. Space science reviews 155(1–4):177–218

    Article  Google Scholar 

  51. Finlay C, Lesur V, Thébault E, Vervelidou F, Morschhauser A, Shore R (2017) Challenges handling magnetospheric and ionospheric signals in internal geomagnetic field modelling. Space Science Reviews 206(1–4), 157–189

    Article  Google Scholar 

  52. Finlay C, Kloss C, Olsen N, Hammer M, Tøffner-Clausen L, Grayver A, Kuvshinov A (2020) The CHAOS-7 geomagnetic field model and observed changes in the South Atlantic Anomaly. Earth Planets Space 72(156)

  53. Finlay CC (2008) Course 8 – Waves in the presence of magnetic fields, rotation and convection. In: Cardin P, Cugliandolo L (eds) Dynamos, Les Houches, vol 88, Elsevier, pp 403–450.https://doi.org/10.1016/S0924-8099(08)80012-1

  54. Finlay CC, Jackson A (2003) Equatorially dominated magnetic field change at the surface of Earth’s core. Science 300(5628):2084–2086. https://doi.org/10.1126/science.1083324

  55. Finlay CC, Olsen N, Kotsiaros S, Gillet N, Tøffner-Clausen L (2016) Recent geomagnetic secular variation from Swarm and ground observatories as estimated in the CHAOS-6 geomagnetic field model. Earth, Planets and Space 68(1), 1–18

    Article  Google Scholar 

  56. Fournier A, Hulot G, Jault D, Kuang W, Tangborn A, Gillet N, Canet E, Aubert J, Lhuillier F (2010) An introduction to data assimilation and predictability in geomagnetism. Space science reviews 155(1–4):247–291

    Article  Google Scholar 

  57. Gastine T, Aubert J, Fournier A (2020) Dynamo-based limit to the extent of a stable layer atop Earth’s core. Geophys J Int 222(2):1433–1448

  58. Gerick F (2020) Modes magnéto-coriolis rapides et couples de pression résultant des modes de torsion d’alfvén dans les noyaux planétaires. PhD thesis, Université GrenobleAlpes, France

  59. Gerick F, Jault D, Noir J (2021) Fast quasi-geostrophic magneto-coriolis modes in the Earth’s Core. Geophys Res Lett 48(4):e2020GL090,803. https://doi.org/10.1029/2020GL090803

  60. Gillet N (2019) Spatial and temporal changes of the geomagnetic field: Insights from forward and inverse core field models. In: Mandea M, Korte M, Yau A, Petrovsky E (eds) Geomagnetism, aeronomy and space weather: a journey from the Earth’s Core to the Sun. Special Publications of the International Union of Geodesy and Geophysics, Cambridge University Press, pp 115–132. https://doi.org/10.1017/9781108290135.010

  61. Gillet N, Jault D, Canet E, Fournier A (2010) Fast torsional waves and strong magnetic field within the Earth’s core. Nature 465(7294):74–77

    Article  Google Scholar 

  62. Gillet N, Schaeffer N, Jault D (2011) Rationale and geophysical evidence for quasi-geostrophic rapid dynamics within the Earth’s outer core. Phys Earth Planet Int 187(3):380–390

    Article  Google Scholar 

  63. Gillet N, Jault D, Finlay C, Olsen N (2013) Stochastic modelling of the Earth’s magnetic field: inversion for covariances over the observatory era. Geochem Geophys Geosyst 14(4):766–786. https://doi.org/10.1002/ggge.2004441

  64. Gillet N, Jault D, Finlay C (2015) Planetary gyre, time-dependent eddies, torsional waves, and equatorial jets at the Earth’s core surface. J Geophys Res Solid Earth 120(6):3991–4013

  65. Gillet N, Jault D, Canet E (2017) Excitation of travelling torsional normal modes in an Earth’s core model. Geophys J Int 210(3):1503–1516

  66. Gillet N, Huder L, Aubert J (2019) A reduced stochastic model of core surface dynamics based on geodynamo simulations. Geophys J Int 219(1), 522–539

    Article  Google Scholar 

  67. Gubbins D, Davies C (2013) The stratified layer at the core-mantle boundary caused by barodiffusion of oxygen, sulphur and silicon. Phys Earth Planet Int 215:21–28, doi: 10.1016/j.pepi.2012.11.001

    Article  Google Scholar 

  68. Gubbins D, Alfè D, Davies C, Pozzo M (2015) On core convection and the geodynamo: effects of high electrical and thermal conductivity, transport properties of the Earth’s Core. Phys Earth Planet Int 247:56–64. https://doi.org/10.1016/j.pepi.2015.04.002

  69. Guervilly C, Cardin P, Schaeffer N (2019) Turbulent convective length scale in planetary cores. Nature 570(7761), 368–371

    Article  Google Scholar 

  70. Hammer MD, Finlay CC (2019) Local averages of the core-mantle boundary magnetic field from satellite observations. Geophys J Int 216(3), 1901–1918

    Article  Google Scholar 

  71. Hammer MD, Cox GA, Brown WJ, Beggan CD, Finlay CC (2021a) Geomagnetic Virtual Observatories: monitoring geomagnetic secular variation with the Swarm satellites. Earth, Planets and Space 73(1), 1–22

    Article  Google Scholar 

  72. Hammer MD, Finlay CC, Olsen N (2021b) Applications for cryosat-2 satellite magnetic data in studies of earth’s core field variations. Earth Planets Space 73(1):1–22

    Article  Google Scholar 

  73. Hardy CM, Livermore PW, Niesen J, Luo J, Li K (2018) Determination of the instantaneous geostrophic flow within the three-dimensional magnetostrophic regime. Proc R Soc A Math Phys Eng Sci 474(2218):20180412

    Google Scholar 

  74. Helffrich G, Kaneshima S (2010) Outer-core compositional stratification from observed core wave speed profiles. Nature 468(7325), 807–810

    Article  Google Scholar 

  75. Helffrich G, Kaneshima S (2013) Causes and consequences of outer core stratification. Phys Earth Planet Int 223:2–7. https://doi.org/10.1016/j.pepi.2013.07.005, sI:13th SEDI conference

  76. Hellio G, Gillet N (2018) Time-correlation-based regression of the geomagnetic field from archeological and sediment records. Geophys J Int 214(3), 1585–1607, DOI: 10.1093/gji/ggy214

    Article  Google Scholar 

  77. Hide R (1966) Free hydromagnetic oscillations of the Earth’s core and the theory of the geomagnetic secular variation. Phil Trans R Soc London A Math Phys Eng Sci 259(1107):615–647. https://doi.org/10.1098/rsta.1966.0026

  78. Hide R (1969) Interaction between the Earth’s liquid core and solid mantle. Nature 222(5198):1055–1056

  79. Holme R (2015) Large scale flow in the core. In: Olson P, Schubert G (eds) Treatise in geophysics, core dynamics, vol 8, chap 4, pp 91–113. Elsevier

  80. Holme R, De Viron O (2013) Characterization and implications of intradecadal variations in length of day. Nature 499(7457), 202–204

    Article  Google Scholar 

  81. Holschneider M, Lesur V, Mauerberger S, Baerenzung J (2016) Correlation-based modeling and separation of geomagnetic field components. J Geophys Res: Solid Earth 121(5), 3142–3160

    Article  Google Scholar 

  82. Hori K, Jones CA, Teed RJ (2015) Slow magnetic rossby waves in the Earth’s core. Geophys Res Lett 42(16):6622–6629. https://doi.org/10.1002/2015GL064733

  83. Hori K, Teed RJ, Jones CA (2018) The dynamics of magnetic Rossby waves in spherical dynamo simulations: A signature of strong-field dynamos? Phys Earth Planet Int 276:68–85. https://doi.org/10.1016/j.pepi.2017.07.008

    Article  Google Scholar 

  84. Huder L, Gillet N, Finlay CC, Hammer MD, Tchoungui H (2020) COV-OBS.x2: 180 years of geomagnetic field evolution from ground-based and satellite observations. Earth Planets Space 72:160. https://doi.org/10.1186/s40623-020-01194-2

    Article  Google Scholar 

  85. Huguet L, Amit H, Alboussiere T (2016) Magnetic to magnetic and kinetic to magnetic energy transfers at the top of the Earth’s core. Geophys J Int 207(2):934–948

    Article  Google Scholar 

  86. Irving JC, Cottaar S, Lekić V (2018) Seismically determined elastic parameters for Earth‘s outer core. Sci Adv 4:eaar2538

  87. Jackson A, Maffei S (2020) Plesio-geostrophy for Earth’s core: I. basic equations, inertial modes and induction. Proc R Soc A 476(2243):20200,513

  88. Jault D (2008) Axial invariance of rapidly varying diffusionless motions in the Earth’s core interior. Phys Earth Planet Int 166(1–2):67–76

  89. Jault D (2015) Illuminating the electrical conductivity of the lowermost mantle from below. Geophys J Int 202(1), 482–496

    Article  Google Scholar 

  90. Jault D, Finlay CC (2015) Waves in the core and mechanical core-mantle interactions. In: Schubert G, Olson P (eds) Treatise on geophysics, core dynamics, 2nd edition, vol 8, Oxford, chap 8.09, pp 225–244. Elsevier

  91. Jones CA (2011) Planetary magnetic fields and fluid dynamos. Annual Review of Fluid Mechanics 43:583–614

    Article  Google Scholar 

  92. Kaneshima S, Helffrich G (2013) Vp structure of the outermost core derived from analysing large-scale array data of SmKS waves. Geophys J Int 193:1537–1555

    Article  Google Scholar 

  93. Kerswell RR (1994) Tidal excitation of hydromagnetic waves and their damping in the Earth. J Fluid Mech 274:219–241, DOI: 10.1017/S0022112094002107

    Article  Google Scholar 

  94. Kloss C, Finlay CC (2019) Time-dependent low-latitude core flow and geomagnetic field acceleration pulses. Geophys J Int 217(1), 140–168

    Article  Google Scholar 

  95. Knezek N, Buffett B (2018) Influence of magnetic field configuration on magnetohydrodynamic waves in Earth’s core. Phys Earth Planet Int 277:1–9

  96. Knezek NR (2019) Equatorial magnetic waves in the stratified ocean of Earth’s core. PhD thesis, University of California, Berkeley

  97. Konôpkovà Z, McWilliams RS, Gómez-Pérez N, Goncharov AF (2016) Direct measurement of thermal conductivity in solid iron at planetary core conditions. Nature 534:99–101

    Article  Google Scholar 

  98. Labbé F, Jault D, Gillet N (2015) On magnetostrophic inertia-less waves in quasi-geostrophic models of planetary cores. Geophys Astrophys Fluid Dyn 109(6), 587–610

    Article  Google Scholar 

  99. Landeau M, Olson P, Deguen R, Hirsh BH (2016) Core merging and stratification following giant impact. Nature Geoscience 9(10), 786–789, DOI: https://doi.org/10.1038/ngeo2808

    Article  Google Scholar 

  100. Lay T, Hernlund J, Buffett BA (2008) Core-mantle boundary heat flow. Nature Geoscience 1(1), 25–32, DOI: https://doi.org/10.1038/ngeo.2007.44

    Article  Google Scholar 

  101. Le Bars M, Couston LA, Favier B, Léard P, Lecoanet D, Le Gal P (2020) Fluid dynamics of a mixed convective/stably stratified system - A review of some recent works. Comptes Rendus Physique 21:151–164

    Article  Google Scholar 

  102. Lesur V, Wardinski I, Rother M, Mandea M (2008) GRIMM: the GFZ reference internal magnetic model based on vector satellite and observatory data. Geophys J Int 173(2), 382–394

    Article  Google Scholar 

  103. Lesur V, Wardinski I, Asari S, Minchev B, Mandea M (2010) Modelling the Earth’s core magnetic field under flow constraints. Earth Planets Space 62(6):503–516

  104. Lesur V, Wardinski I, Baerenzung J, Holschneider M (2018) On the frequency spectra of the core magnetic field gauss coefficients. Phys Earth Planet Int 276:145–158

    Article  Google Scholar 

  105. Lesur V, Gillet N, Hammer M, Mandea M (2021) Rapid variations of Earth’s core magnetic field. Surv Geophys

  106. Li WJ, Li Z, He XT, Wang C, Zhang P (2021) Constraints on the thermal evolution of Earth’s core from ab initio calculated transport properties of FeNi liquids. Earth Planet Sci Lett 562(116):852. https://doi.org/10.1016/j.epsl.2021.116852

  107. Lin Y, Ogilvie GI (2020) Ohmic dissipation in the Earth’s outer core resulting from the free inner core nutation. Earth Planet Sci Lett 530(115):888

  108. Lister JR, Buffett BA (1998) Stratification of the outer core at the core-mantle boundary. Phys Earth Planet Int 105(1), 5–19, doi: 10.1016/S0031-9201(97)00082-4

    Article  Google Scholar 

  109. Livermore PW, Hollerbach R, Finlay CC (2017) An accelerating high-latitude jet in Earth’s core. Nature Geoscience 10(1):62–68

  110. Livermore PW, Finlay CC, Bayliff M (2020) Recent north magnetic pole acceleration towards Siberia caused by flux lobe elongation. Nature Geoscience 13:387–391

    Article  Google Scholar 

  111. Maffei S, Jackson A, Livermore PW (2017) Characterization of columnar inertial modes in rapidly rotating spheres and spheroids. Proc R Soc A Math Phys Eng Sci 473(2204):20170181

  112. Malkus WVR (1967) Hydromagnetic planetary waves. J Fluid Mech 28:792–802

    Article  Google Scholar 

  113. Mandea M, Holme R, Pais A, Pinheiro K, Jackson A, Verbanac G (2010) Geomagnetic jerks: rapid core field variations and core dynamics. Space science reviews 155(1–4):147–175

    Article  Google Scholar 

  114. McNamara AK (2019) A review of large low shear velocity provinces and ultra low velocity zones, linking plate tectonics and volcanism to deep earth dynamics—a tribute to Trond H. Torsvik. Tectonophysics 760:199–220. https://doi.org/10.1016/j.tecto.2018.04.015

  115. Meduri DG, Wicht J (2016) A simple stochastic model for dipole moment fluctuations in numerical dynamo simulations. Frontiers in Earth Science 4:38

    Article  Google Scholar 

  116. Nataf HC, Schaeffer N (2015) Turbulence in the core. In: Schubert G, Olson P (eds) Treatise on Geophysics, Core Dynamics, 2nd edition, vol 8, Elsevier, Oxford, pp 161–181

    Chapter  Google Scholar 

  117. Ohta K, Yagi T, Hirose K, Ohishi Y (2017) Thermal conductivity of ferropericlase in the Earth’s lower mantle. Earth Planet Sci Lett 465:29–37

  118. Olsen N, Mandea M (2007) Investigation of a secular variation impulse using satellite data: The 2003 geomagnetic jerk. Earth Planet Sci Lett 255(1), 94–105, doi: https://doi.org/10.1016/j.epsl.2006.12.008

    Article  Google Scholar 

  119. Olson PL, Christensen UR, Driscoll PE (2012) From superchrons to secular variation: a broadband dynamo frequency spectrum for the geomagnetic dipole. Earth Planet Sc Lett 319:75–82

    Article  Google Scholar 

  120. Pais M, Jault D (2008) Quasi-geostrophic flows responsible for the secular variation of the Earth’s magnetic field. Geophys J Int 173(2):421–443

  121. Pick L, Korte M, Thomas Y, Krivova N, Wu CJ (2019) Evolution of large-scale magnetic fields from near-Earth space during the last 11 solar cycles. J Geophys Res: Space Physics 124(4), 2527–2540

    Google Scholar 

  122. Pozzo M, Davies C, Gubbins D, Alfe D (2012) Thermal and electrical conductivity of iron at Earth’s core conditions. Nature 485(7398):355–358

  123. Püthe C, Kuvshinov A, Khan A, Olsen N (2015) A new model of Earth’s radial conductivity structure derived from over 10 yr of satellite and observatory magnetic data. Geophys J Int 203(3):1864–1872

  124. Roberts PH, Aurnou JM (2012) On the theory of core-mantle coupling. Geophys Astrophys Fluid Dyn 106(2), 157–230

    Article  Google Scholar 

  125. Roberts PH, Stewartson K (1974) On finite amplitude convection in a rotating magnetic system. Phil Trans R Soc London Series A, Mathematical and Physical Sciences 277(1269), 287–315, DOI: https://doi.org/10.1098/rsta.1974.0052

    Article  Google Scholar 

  126. Roberts PH, Wu CC (2014) On the modified taylor constraint. Geophys Astrophys Fluid Dyn 108(6), 696–715

    Article  Google Scholar 

  127. Ropp G, Lesur V, Baerenzung J, Holschneider M (2020) Sequential modelling of the Earth’s core magnetic field. Earth Planets Space 72(1):1–15

  128. Sabaka TJ, Olsen N, Purucker ME (2004) Extending comprehensive models of the Earth’s magnetic field with Ørsted and CHAMP data. Geophys J Int 159(2):521–547. https://doi.org/10.1111/j.1365-246X.2004.02421.x

  129. Sanchez S, Wicht J, Bärenzung J (2020) Predictions of the geomagnetic secular variation based on the ensemble sequential assimilation of geomagnetic field models by dynamo simulations. Earth, Planets, and Space 72(1):157, DOI: https://doi.org/10.1186/s40623-020-01279-y

    Article  Google Scholar 

  130. Schaeffer N, Cardin P (2005) Quasigeostrophic model of the instabilities of the Stewartson layer in flat and depth-varying containers. Phys Fluids 17(10):104111. https://doi.org/10.1063/1.2073547

  131. Schaeffer N, Jault D (2016) Electrical conductivity of the lowermost mantle explains absorption of core torsional waves at the equator. Geophys Res Lett 43(10), 4922–4928

    Article  Google Scholar 

  132. Schaeffer N, Jault D, Cardin P, Drouard M (2012) On the reflection of alfvén waves and its implication for Earth’s core modelling. Geophys J Int 191(2):508–516

  133. Schaeffer N, Jault D, Nataf HC, Fournier A (2017) Turbulent geodynamo simulations: a leap towards Earth’s core. Geophys J Int 211(1):1–29

  134. Schwaiger T, Gastine T, Aubert J (2019) Force balance in numerical geodynamo simulations: a systematic study. Geophys J Int 219(Supplement\_1):S101–S114

  135. Soloviev A, Chulliat A, Bogoutdinov S (2017) Detection of secular acceleration pulses from magnetic observatory data. Phys Earth Planet Int 270:128–142

    Article  Google Scholar 

  136. Stanley S, Bloxham J, Hutchison WE, Zuber MT (2005) Thin shell dynamo models consistent with Mercury’s weak observed magnetic field. Earth Planet Sci Lett 234(1):27–38. https://doi.org/10.1016/j.epsl.2005.02.040

  137. Takehiro S, Lister JR (2001) Penetration of columnar convection into an outer stably stratified layer in rapidly rotating spherical fluid shells. Earth Planet Sci Lett 187:357–366

    Article  Google Scholar 

  138. Taylor JB (1963) The magnetohydrodynamics of a rotating fluid and the Earth’s dynamo problem. Proc R Soc London A 274:274–283

  139. Teed RJ, Jones CA, Tobias SM (2014) The dynamics and excitation of torsional waves in geodynamo simulations. Geophys J Int 196(2), 724–735

    Article  Google Scholar 

  140. Teed RJ, Jones CA, Tobias SM (2015) The transition to Earth-like torsional oscillations in magnetoconvection simulations. Earth Planet Sci Lett 419:22–31

    Article  Google Scholar 

  141. Teed RJ, Jones CA, Tobias SM (2018) Torsional waves driven by convection and jets in Earth’s liquid core. Geophys J Int 216(1):123–129. https://doi.org/10.1093/gji/ggy416

  142. Tobias S (2021) The turbulent dynamo. J Fluid Mech 912(P1). https://doi.org/10.1017/jfm.2020.1055

  143. Triana SA, Rekier J, Trinh A, Dehant V (2019) The coupling between inertial and rotational eigenmodes in planets with liquid cores. Geophys J Int 218(2), 1071–1086, DOI: 10.1093/gji/ggz212

    Article  Google Scholar 

  144. Triana SA, Trinh A, Rekier J, Zhu P, Dehant V (2021) The viscous and ohmic damping of the Earth’s free core nutation. J Geophys Res: Solid Earth 126(4):e2020JB021042. https://doi.org/10.1029/2020JB021042

  145. Velímskỳ J (2010) Electrical conductivity in the lower mantle: Constraints from CHAMP satellite data by time-domain EM induction modelling. Phys Earth Planet Int 180(3–4), 111–117

    Article  Google Scholar 

  146. Vidal J, Schaeffer N (2015) Quasi-geostrophic modes in the Earth’s fluid core with an outer stably stratified layer. Geophys J Int 202:2182–2193

  147. Wicht J, Christensen UR (2010) Torsional oscillations in dynamo simulations. Geophys J Int 181:1367–1380

    Google Scholar 

  148. de Wijs GA, Kresse G, Vočadlo L, Dobson D, Alfe D, Gillan MJ, Price GD (1998) The viscosity of liquid iron at the physical conditions of the Earth’s core. Nature 392(6678):805–807

  149. Yan C, Stanley S (2018) Sensitivity of the geomagnetic octupole to a stably stratified layer in the Earth’s core. Geophys Res Lett 45(20):11005–11011. https://doi.org/10.1029/2018GL078975

  150. Zatman S, Bloxham J (1997) Torsional oscillations and the magnetic field within the Earth’s core. Nature 388(6644):760–763

  151. Zhang K (1992) On inertial waves in the Earth’s fluid core. Geophys Res Lett 19:737–740

  152. Zhang K (1993) On equatorially trapped boundary inertial waves. J Fluid Mech 248:203–217, DOI: 10.1017/S0022112093000746

    Article  Google Scholar 

  153. Zhang K, Earnshaw P, Liao X, Busse F (2001) On inertial waves in a rotating fluid sphere. J Fluid Mech 437:103

    Article  Google Scholar 

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Acknowledgements

NG and DJ were partially supported by the French Centre National d’Etudes Spatiales (CNES) for the study of Earth’s core dynamics in the context of the Swarm mission of ESA. NG and DJ contributions have been also funded by ESA in the framework of EO Science for Society, through contract 4000127193/19/NL/IA (SWARM + 4D Deep Earth: Core). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (GRACEFUL Synergy Grant agreement No. 855677). RA would like to thank Sabine Stanley and Ankit Barik for fruitful discussions and comments pertaining to Sect. 3. We thank two anonymous referees for their comments that helped improve the quality of the manuscript. We thank J. Aubert for making available the data from the 71%-path dynamo.

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Gillet, N., Gerick, F., Angappan, R. et al. A Dynamical Prospective on Interannual Geomagnetic Field Changes. Surv Geophys (2021). https://doi.org/10.1007/s10712-021-09664-2

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Keywords

  • Geomagnetic secular variation
  • Earth’s core dynamics
  • Magnetohydrodynamic waves