Hagay AMIT


CR1

LPG Nantes

Bât. 4, porte 36

Tél : +33 (0)251125568

Mél : Hagay.Amit@univ-nantes.fr

 hagayA

Research Interests:

  • Core flow inversions from geomagnetic secular variation
  • Core-mantle thermal interactions and time-average dynamo properties
  • Geomagnetic field dynamics on various time scales
  • Mechanisms of geomagnetic dipole moment variations
  • Past dynamo on Mars
  • Planetary magnetic fields

 

Publications:

  1. Amit, H., Deguen, D., Driscoll, P., Nakagawa, T., 2019. Editorial: Stratification in the cores of Earth and other planets. Front. Earth. Sci., 7:165. [pdf]
  2. Pinheiro, K. J., Amit, H., Terra-Nova, F., 2019. Geomagnetic jerk features produced using synthetic core flow models. Phys. Earth Planet. Inter., 291, 35-53. [pdf]
  3. Terra-Nova, F., Amit, H., Choblet, G., 2019. Preferred locations of weak surface field in numerical dynamos with heterogeneous core–mantle boundary heat flux: consequences for the South Atlantic Anomaly. Geophys. J. Int., 217, 1179-1199. [pdf]
  4. Zossi, B., Fagre, M., Amit, H., Elias, A. G., 2019. Polar caps during geomagnetic polarity reversals. Geophys. J. Int., 216, 1334-1343. [pdf]
  5. Huguet, L., Amit, H., Alboussière, T., 2018. Geomagnetic Dipole Changes and Upwelling/Downwelling at the Top of the Earth’s Core. Front. Earth Sci., 6:170, doi:10.3389/feart.2018.00170. [pdf]
  6. Peña, D., Amit, H., Pinheiro, K. J., 2018. Deep magnetic field stretching in numerical dynamos. Prog. Earth Planet. Sci., 5:8. [pdf]
  7. Thébault, E., Langlais, B., Oliveira, J. S., Amit, H., Leclercq, L., 2018. A time-averaged regional model of the Hermean magnetic field. Phys. Earth Planet. Inter., 276, 93-105. [pdf]
  8. Saturnino, D., Langlais, B., Amit, H., Civet, F., Mandea, M., Beucler, É., 2018. Combining virtual observatory and equivalent source dipole approaches to describe the geomagnetic field with Swarm measurements. Phys. Earth Planet. Inter., 276, 118-133. [pdf]
  9. Amit, H., Coutelier, M., Christensen, U., 2018. On equatorially symmetric and antisymmetric geomagnetic secular variation timescales. Phys. Earth Planet. Inter., 276, 190-201. [pdf]
  10. Terra-Nova, F., Amit, H., Hartmann, G. A., Trindade, R. I. F., Pinheiro, K. J., 2017. Relating the South Atlantic Anomaly and geomagnetic flux patches. Phys. Earth Planet. Inter., 266, 39-53. [pdf]
  11. Choblet, G., Amit, H., Husson, L., 2016. Constraining mantle convection models with palaeomagnetic
    reversals record and numerical dynamos. Geophys. J. Int., 207, 1165-1184. [pdf]
  12. Huguet, L., Amit, H., Alboussière, T., 2016. Magnetic to magnetic and kinetic to magnetic energy transfers at the top of the Earth’s core. Geophys. J. Int., 207, 934-948. [pdf]
  13. Terra-Nova, F., Amit, H., Hartmann, G. A., Trindade, R. I. F., 2016. Using archaeomagnetic field models to constrain the physics of the core: robustness and preferred locations of reversed flux patches. Geophys. J. Int., 206, 1890-1913. [pdf]
  14. Peña, D., Amit, H., Pinheiro, K. J., 2016. Magnetic field stretching at the top of the shell of numerical dynamos. Earth Planets Space, 68:78. [pdf]
  15. Sahoo, S., Sreenivasan, B., Amit, H., 2016. Dynamos driven by weak thermal convection and heterogeneous outer boundary heat flux. Phys. Earth Planet. Inter., 250, 35-45. [pdf]
  16. Amit, H., Choblet, G., Olson, P., Monteux, J., Deschamps, F., Langlais, B., Tobie, G., 2015. Towards more realistic core-mantle boundary heat flux patterns: a source of diversity in planetary dynamos. Prog. Earth Planet. Sci., 2:26, DOI: 10.1186/s40645-015-0056-3. [pdf]
  17. Amit, H., Deschamps, F., Choblet, G., 2015. Numerical dynamos with outer boundary heat flux inferred from probabilistic tomography—consequences for latitudinal distribution of magnetic flux. Geophys. J. Int., 203, 840-855. [pdf]
  18. Olson, P., Amit, H., 2015. Mantle superplumes induce geomagnetic superchrons. Front. Earth Sci., 3:38, doi: 10.3389/feart.2015.00038. [pdf]
  19. Oliveira, J. S., Langlais, B., Pais, M. A., Amit, H., 2015. A modified Equivalent Source Dipole method to model partially distributed magnetic field measurements, with application to Mercury. J. Geophys. Res., 120, doi:10.1002/2014JE004734.[pdf]
  20. Terra-Nova, F., Amit, H., Hartmann, G. A., Trindade, R. I. F., 2015. The time dependence of reversed archeomagnetic flux patches. J. Geophys. Res., 120, 691-704. [pdf]
  21. Monteux, J., Amit, H., Choblet, G., Langlais, B., Tobie, G., 2015. Giant impacts, heterogeneous mantle heating and a past hemispheric dynamo on Mars. Phys. Earth Planet. Inter., 240, 114-124. [pdf]
  22. Amit, H., Olson, P., 2015. Lower mantle superplume growth excites geomagnetic reversals. Earth Planet. Sci. Lett., 414, 68-76. [pdf]
  23. Pinheiro, K.J., Jackson, A., Amit, H., 2015. On the applicability of Backus’ mantle filter theory. Geophys. J. Int., 200, 1336-1346. [pdf]
  24. Langlais, B., Amit, H., Larnier, H., Thébault, E., Mocquet, A., 2014. A new model for the (geo)magnetic power spectrum, with application to planetary dynamo radii. Earth Planet. Sci. Lett., 401, 347-358. [pdf]
  25. Amit, H., 2014. Can downwelling at the top of the Earth's core be detected in the geomagnetic secular variation? Phys. Earth Planet. Inter., 229, 110-121. [pdf]
  26. Olson, P., Amit, H., 2014. Magnetic reversal frequency scaling in dynamos with thermochemical convection. Phys. Earth Planet. Inter., 229, 122-133. [pdf][Nature Geosci. research highlight]
  27. Amit, H., Pais, M.A., 2013. Differences between tangential geostrophy and columnar flow. Geophys. J. Int., 194, 145-157. [pdf]
  28. Monteux, J., Schaeffer, N., Amit, H., Cardin, P., 2012. Can a sinking metallic diapir generate a dynamo? J. Geophys. Res., 117, E10005, doi:10.1029/2012JE004075. [pdf] 
  29. Huguet, L., Amit, H., 2012. Magnetic energy transfer at the top of Earth's core. Geophys. J. Int., 190, 856-870. [pdf].  
  30. Amit, H., Choblet, G., 2012. Mantle-driven geodynamo features - effects of compositional and narrow D'' anomalies. Phys. Earth Planet. Inter., 190-191, 34-43. [pdf] [Nature Geosci. research highlight] 
  31. Amit, H., Korte, M., Aubert, J., Constable, C., Hulot, G., 2011. The time-dependence of intense archeomagnetic flux patches. J. Geohys. Res., 116, B12106, doi:10.1029/2011JB008538. [pdf]
  32. Amit, H., Christensen, U., Langlais, B., 2011. The influence of degree-1 mantle heterogeneity on the past dynamo of Mars. Phys. Earth Planet. Inter., 189, 63-79. [pdf]
  33. Finlay, C.C., Amit, H., 2011. On flow magnitude and field-flow alignment at Earth's core surface. Geophys. J. Int., 186, 175-192. [pdf]
  34. Amit, H., Leonhardt, R., Wicht, J., 2010. Polarity reversals from paleomagnetic observations and numerical dynamo simulations. Space Sci. Rev., 155, 293-335. [pdf]
  35. Amit, H., Aubert, J., Hulot, G., 2010. Stationary, oscillating or drifting mantle-driven geomagnetic flux patches? J. Geophys. Res., 115, B07108, doi:10.1029/2009JB006542. [pdf]
  36. Amit, H., Olson, P., 2010. A Dynamo Cascade Interpretation of the Geomagnetic Dipole Decrease. Geophys. J. Int., 181, 1411-1427. [pdf]
  37. Amit, H., Choblet, G., 2009. Mantle-driven geodynamo features - effects of post-Perovskite phase transition. Earth Planets Space, 61, 1255-1268. [pdf]
  38. Olson, P., Driscoll, P., Amit, H., 2009. Dipole collapse and reversal precursors in a numerical dynamo. Phys. Earth Planet. Inter., 173, 121-140. [pdf]
  39. Amit, H., Christensen, U., 2008. Accounting for magnetic diffusion in core flow inversions from geomagnetic secular variation. Geophys. J. Int., 175, 913-924. [pdf]
  40. Langlais, B., Amit, H., 2008. The Past Martian Dynamo, Science, 321, 1784-1785. [pdf]
  41. Amit, H., Aubert, J., Hulot, G., Olson, P., 2008. A simple model for mantle-driven flow at the top of Earth's core. Earth Planets Space, 60, 845-854. [pdf]
  42. Aubert, J., Amit, H., Hulot, G., Olson, P., 2008. Thermo-chemical flows couple the Earth's inner core growth to mantle heterogeneity. Nature, 454, 758-761. [pdf]
  43. Amit, H., Olson, P., 2008. Geomagnetic dipole tilt changes induced by core flow. Phys. Earth Planet. Inter., 166, 226-238. [pdf]
  44. Aubert, J., Amit, H., Hulot, G., 2007. Detecting thermal boundary control in surface flows from numerical dynamos. Phys. Earth Planet. Inter., 160, 143-156. [pdf]
  45. Amit, H., Olson, P., Christensen, U., 2007. Tests of core flow imaging methods with numerical dynamos. Geophys. J. Int., 168, 27-39. [pdf]
  46. Olson, P., Amit, H., 2006. Changes in Earth's dipole. Naturwissenschaften, 93, 11, 519-542. [pdf]
  47. Amit, H., Olson, P., 2006. Time-average and time-dependent parts of core flow. Phys. Earth Planet. Inter., 155, 120-139. [pdf]
  48. Amit, H., Olson, P., 2004. Helical core flow from geomagnetic secular variation. Phys. Earth Planet. Inter., 147, 1-25. [pdf]
  49. Amit, H., Lyakhovsky, V., Katz, A., Starinsky, A., Burg, A., 2002. Interpretation of spring recession curves. Groundwater, 40, 543-551. [pdf]

 

Ph.D. Thesis

HDR

Conferences

Invited talks

CV

 

 

  • Core flow inversions from geomagnetic secular variation

helicity_dynamo

Above: Helical flow at the top of the free stream in a numerical dynamo model. From Amit et al. (2007).

Right: Time-average core flow and time-average zonal angular velocity for 1840-1990 from inversions of geomagnetic secular variation. From Amit and Olson (2006). 

aveflow

 

  • Core-mantle thermal interactions and time-average dynamo properties

mantle_zonal

Above: North-south asymmetry in zonal core flow may suggest mantle control. From Amit and Olson (2006).

Right: Accounting for post-Perovskite in lower mantle sesimic anomalies may improve recovery of observed geodynamo quantities, e.g. east-west dichotmy in upper inner core seismic properties. From Amit and Choblet (2009).

qicb

 

  • Geomagnetic field dynamics on various time scales

dif

Above: Radial and tangential diffusion correlations at the top of the free stream in a numerical dynamo model. From Amit and Christensen (2008).

Right: Identification and tracking of intense magnetic flux patches in a numerical dynamo model with tomographic outer boundary heat flux. From Amit et al. (2010).

drift

 

  • Mechanisms of geomagnetic dipole moment variations
medot

cascade

Left: Advective contributions to equatorial dipole moment change represent sources and sinks of dipole tilt variations. From Amit and Olson (2008).

Above: Magnetic energy cascade from low to high spherical harmonics may explain rapid historical decrease of the geomagnetic axial dipole. From Amit and Olson (2010).

 

  • Past dynamo on Mars
medot

Above: (a) Current Martian crustal magnetic field intensity at an altitude of 400 km in nT (colors) plotted over surface topography; (b) The zonal profile of the longitudinally averaged field intensity.

Right: Time-average magnetic field properties in a dynamo model with Y10 imposed heat flux pattern on the CMB: (a) Time-average radial field on the CMB; (b) Time-average unsigned radial field on the CMB; (c) The intensity of the time-average magnetic field vector on Mars' surface; (d) The time-average field intensity on Mars' surface; (e) Zonal profile of the intensity of the time-average field; (f) Zonal profile of the time-average field intensity; (g) Meridional profile of the intensity of the time-average field; (h) Meridional profile of the time-average field intensity.

From Amit et al. (2011).

cascade

 

  • Planetary magnetic fields