Description of the researches conducted by the staff members

  1. Dr. Ph. Cardin (LGIT): he is studying the motions set out in the fluid outer core by the precession of its solid container, in collaboration with D. Jault. He is now running numerical models but plans to devise an experimental one in the new facilities at Grenoble University. With H.C. Nataf, he will also study magnetoconvection in a sphere filled with helium.

  2. A. Chulliat (IPGP) (Ph.D. student): he is currently working with G. Hulot on some new ways of investigating core flows, using a local approach based on the tangentially geostrophic approximation. He will start working as a Ph. D. at the beginning of September.

  3. Dr. P. Defraigne (ROB): she has been working on modeling mantle convection in order to obtain the boundary displacements inside the Earth, the geoid and the plate velocities, in particular in order to evaluate the CMB displacement. She could compute the associated FCN period. She also worked on stacking VLBI nutation and superconducting data in order to obtain the observed value of the FCN. She has also incorporated mantle convection results in a new nutation model.

  4. Dr. V. Dehant (ROB): she has been working on the Earth interior modeling in the frame of nutation theory (as well as earth tides); she has been working on core modes in the theoretical point of view in the frame of superconducting gravimeters; she has been working on the FCN and FICN using both the analytical approach as well as the numerical integration approach; she has been working on the FCN period and amplitude from nutation data (free oscillations as well as resonance effects). She is currently continuing to work on nutation modeling incorporating new physics of the Earth interior and lenght-of-day (lod) modeling related to the core effects. She is presently extending her work to the planet Mars.

  5. Dr. O. de Viron (IPGP): he is working on the effects of the atmosphere on nutations and LOD; he is performing numerical computations based on meteorological data and theoretical computations based either on the angular momentum conservation approach or on the torque approach (as for the core, he is using the pressure torque, the gravitational torque and the friction torque). He is presently extending his work on other geophysical fluids, namely the ocean and the fluid core of the Earth.

  6. E. Dormy (IPGP) (PostDoc): he is working on numerical modeling of the Geodynamo and turbulent motions in the Earth's core. He is concerned with numerical difficulties associated with the modeling of motions in the core. He is presently working at UCLA.

  7. Dr. M. Greff-Lefftz (IPGP): she has been working on modeling the elastic, viscoelastic and fluid deformations of the Earth induced by external sources as well as internal sources (internal load within the mantle, pressure and tangential traction at the CMB and ICB ...). She has computed equatorial electromagnetic torque and topographic torque induced by geostrophic motions at the CMB in order to explain the observed decade variations of the Earth rotation. At the present, she is investigating the influence of the magnetic field on the rotational eigenfrequencies of the Earth.

  8. Dr. J. Hinderer (EOPGS): he has been working on the theory of the rotation and deformation of an earth model including a solid inner core, fluid outer core, elastic mantle surrounded by atmospheric and oceanic thin surficial layers. He is mainly interested in the link between surface gravity changes and the structure and dynamics of the Earth especially through high quality observations provided by a network of superconducting gravimeters (Global Geodynamics Project).

  9. Dr. R. Holme (FGZ, Potsdam): he has been working on electromagnetic core-mantle coupling, demonstrating that this is indeed a possible mechanism to explain decadal variations in lenght of day. He is studying the influence of a priori assumptions on models of fluid flow and the core angular momentum calculated from them. He is also interested in inverse theory and geomagnetic field modelling, and is a member of the CHAMP satellite team.

  10. Dr. G. Hulot (IPGP): his main interests are in characterizing the spatiotemporal properties of the main magnetic field and of the flows that are responsible for the observed secular variation. His work involves magnetic data analysis and reconstruction of core flows. He has been investigating (both theoretically and numerically) the dynamical consequences of such flows on the Earth's rotation (LOD variations, polar motions). He is currently working on some new ways of investigating core flows (with A. Chulliat), and on the possibility of seeing zonal flows that could relate to the presence of an inner core (with A. Pais). He is also investigating the possible influence of an inner core on core-mantle interactions (again with A. Pais).

  11. Dr. A. Jackson (ULeeds): He is interested in morphology of magnetic field at the core mantle interface using contemporary and historical data. Currently engaged in project to compile data back to 16th century from maritime sources. Also working on construction of models of radial magnetic field and its secular variation compatible with frozen flux and radial vorticity conservation. Long-term interest in retrieval of core fluid flow, and implications for Earth rotation.

  12. Dr. D. Jault (LGIT): his main interest is dynamo theory. He is developing numerical models in collaboration with Ph. Cardin. He has studied the different torques that are able to couple the fluid outer core with the solid mantle on a decadal time scale. In particular, he noted that the electrical potential differences, at the CMB, that are responsible for the main part of the electromagnetic torque, have no magnetic signature at the Earth's surface. He is now completing this study with Dr. J. Wicht (Exeter University).

  13. Prof. H. Legros (EOPGS): he has been working on the mantle visco- elastic deformations and on the core topography. He also studied the electromagnetic, topographic and gravitational coupling between the core and the mantle. He was interested with the rotational eigenmodes of the inner core and of the fluid core and presently he is working about the resonances associated with these modes.

  14. Prof. J-L. Le Mouel (IPGP): he is the head of the Geomagnetism Department. He is working on the electromagnetic and topographic core-mantle coupling, both axial and equatorial, on the effects on the long term variations of the Earth's obliquity of the dissipative phenomena at the CMB, and on the correlation between Earth's rotation and geomagnetic events.

  15. J. Noir (LGIT) (Ph.D. student): he is doing a thesis devoted to the study of the precession of a fluid volume under the supervision of D. Jault and Ph. Cardin.

  16. A. Pais (IPGP) (Ph.D. student): she is currently working with G. Hulot on the possibility of seeing zonal flows that could be related to the presence of an inner core. She is also investigating the possible influence of an inner core on core-mantle interactions.

  17. S. Ponsar (ROB) (Ph.D. student): she is presently working (starting a Ph.D. thesis) on the possible influence of the magnetic field on nutations. In particular, she is studying the different coupling mechanisms at the CMB.

  18. Dr. T. Van Hoolst (ROB): he studies the interior structure and evolution of terrestrial planets and stars. Periodic deformations (tides, (astero)seismology) and rotation variations (precession, nutation, polar motion, length-of-day variations) are the dynamical tools used. His present main interest is the deep interior (core) of terrestrial planets. He is actively engaged in research on the influence of an evolving planetary core on the planet's nutations and tides.