Description of the researches conducted by the staff members
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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
- 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).
- 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.
- 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).
- 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.
- 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
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.