Papers by Jacques Hinderer
Geophysical Journal International, 1982
The basic equations describing the dynamical effects of the Earth's fluid core (Liouville, Navier... more The basic equations describing the dynamical effects of the Earth's fluid core (Liouville, Navier-Stokes and elasticity equations) are derived for an ellipsoidal earth model without axial symmetry but with an homogeneous and deformable fluid core and elastic mantle. We develop the balance of moment of momentum up t o the second order and use Love numbers t o describe the inertia tensor's variations. The inertial torque takes into account the ellipticity and the volume change of the liquid core. On the core-mantle boundary we locate dissipative, magnetic and viscous torques. In this way we obtain quite a complete formulation for the Liouville equations. These equations are restricted in order to obtain the usual Chandler and nearly diurnal eigenfrequencies. Then we propose a method for calculating the perturbations of these eigenfrequencies when considering additional terms in the Liouville equations.
Variations temporelles de la gravité en relation avec la dynamique interne de la Terre Apport des... more Variations temporelles de la gravité en relation avec la dynamique interne de la Terre Apport des gravimètres supraconducteurs présentée par
The authors present some examples of Earth's deformation under various physical processes... more The authors present some examples of Earth's deformation under various physical processes, using a Love numbers formalism: taking into account these effects may be usefull when establishing reference systems. Major perturbations are generated by atmospheric loading effects and corresponding deformations are found to reach an amplitude of one centimeter. Other effects are smaller.
C R Acad Sci Ser Ii a, 2001
Ocean loading involves both the dynamic and geometric effects that result from the action of ocea... more Ocean loading involves both the dynamic and geometric effects that result from the action of ocean water masses on the crust. Gravity variations are generated by the direct attraction of the ocean masses, by the deformation of the crust and by the redistribution potential of the masses. Such effects are still perceptible far inland. A Green's function formalism, using loading Love numbers, allows to predict the loading effects. We present here the first French experiment in coastal areas devoted to the study of this phenomenon. The campaign took place in Brest in March 1998. The absolute gravimeter of the French community recorded during four days the gravity changes. Once the standard contributions (body tides, atmospheric pressure effect, polar motion) are removed, the residual variations are mainly due to the ocean loading and they can be confronted to the models. The observed gravity variations exceed by 16 % the theoretical predictions, and we impute this fact to the raw spatial resolution of the global ocean tide models, with a strong consequence near the coasts. Improvements are needed in all the geodetic features of coastal type (tide gauge links, vertical displacement displacement, motion of reference geodetic stations), and also in the validation of the hydrodynamic models by using gravity as an integrating quantity.
As has been recognized for several years, attempts to validate GRACE satellite data using any kin... more As has been recognized for several years, attempts to validate GRACE satellite data using any kind of ground data immediately runs into the problem of horizontal scale lengths. Over Europe we have only 7 GGP stations operating since GRACE observations began and these are insufficient to give more than a simple averaging of local hydrology variations. Yet the approach from averaging ground stations is conceptually correct and would be effective if we had numerous stations all situated at the ground / atmosphere interface. Here we review how a combination of surface and underground stations (i.e. those measuring gravity below a local soil moisture horizon) can be used to validate satellite data. We show results from several GRACE models with the European GGP data since 2002.
For several years, it has been the goal of the Global Geodynamics Project (GGP) to convert high r... more For several years, it has been the goal of the Global Geodynamics Project (GGP) to convert high rate acceleration data recorded on superconducting gravimeters (SG) to a format compatible with the seismic data archived at IRIS. The problem for the GGP community has been to properly establish the metadata for characterizing the response of the instrument, particularly its phase characteristics.
Studia Geophysica et Geodaetica, 2014
Treatise on Geophysics, 2007
A major challenge in water resources research is to document the spatial and temporal variability... more A major challenge in water resources research is to document the spatial and temporal variability of the hydrological processes over short time and space scales. Indeed, the quality of model predictions for resource assessment is dependent on reliable datasets, representative of the hydrological regime and its variations. This issue is particularly sensitive in Sahelian Africa, where available hydrological datasets are scarce. In this study, the variability of the water storage was investigated at the subcatchment scale (< 1km) by an intensive microgravity field campaign. Weekly microgravity surveys were carried out in a small endoreic catchment in Southwest Niger, during three months of the rainy season in 2009. Gravity measurements were performed at 16 stations located near a temporary pond, where rapid infiltration towards the aquifer occurs. The highest (63 μGal) gravity signal was measured on a station located above the pond and is well explained by the direct effect of the ...
Water Resources Research, 2013
The purpose of this paper is to investigate the role of the correlation between atmospheric press... more The purpose of this paper is to investigate the role of the correlation between atmospheric pressure and gravity in the context of a single scalar admittance. We consider two GGP data sets from Boulder and Strasbourg, both of which we processed from the raw data before decimating to 1minute files. The cross correlation and scalar admittance between gravity and pressure were determined for 3 averaging windows of 1 hour, 6 hours and 1 day. The data clearly show that cross correlation and admittance are related; furthermore, the shorter the averaging window the more the scatter in both quantities. We found that when the correlation was high the admittance tended towards a value that was higher for shorter windows and higher frequencies. Our attempts to use the correlation to improve the traditional assumption of a single scalar factor (e.g. -0.3 µgal mbar-1) were unsuccessful, probably due to the inherent noise in the gravity residuals.
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Papers by Jacques Hinderer