@inproceedings{fdi:010020073,
  title = {{C}ontribution de la {F}rance {\`a} l'observation du champ magn{\'e}tique terrestre},
  author = {{B}itterly, {J}. and {M}andea {A}lexandrescu, {M}. and {S}chott, {J}.{J}. and {V}assal, {J}acques},
  editor = {},
  language = {{FRE}},
  abstract = {{T}he aim of our paper is to show the importance of geomagnetic data to the knowledge of the main geomagnetic field and its secular variation, and also of the temporal, in order to survey the {E}arth's environment. {F}irstly, we recall the results obtained on the high-resolution secular variation of the geomagnetic field in two sites situated in {W}estern {E}urope ({L}ondon and {P}aris) over the last four centuries. {T}he declination data are remarkably well correlated between the two sites and can be used to construct a more complete and accurate synthetic series, in which many gaps or times with scattered or uncertain data can be amended. {T}he built declination synthetic series is believed to be valid for much {W}estern {E}urope, and information about the secular variation in this area are obtained. {B}ut, to characterise the geomagnetic field, the spatial variations are also important. {T}o monitor the field variations, an international program has been developed since 1988. {U}nder the {INTERMAGNET} program, high quality data from a global network of geomagnetic observatories are sent in near real time via satellite and computer links to world-wide collection and disseminatin points called "{G}eomagnetic {I}nformation {N}odes" or {GIN}s. {A}ll {INTERMAGNET} observatories operate with the same common specifications (resolution, filtering, sampling rate, data formats etc.) {T}oday, the {INTERMAGNET} observatories data-sets of 1.0 minute values with good baselines are available within minutes and hours from about 60 observatories. {A}nother {INTERMAGNET} goal is to fill out the global geomagnetic observatory distribution. {I}n fact, a recent study specified the minimum number of equally spaced observatories needed to do a degree and order 10 spherical harmonic model of the main field. {T}he model required a minimum of 92 observatories on about a 2,000 km spacing. {E}ight sites would require ocean bottom observatories... ({D}'apr{\`e}s r{\'e}sum{\'e} d'auteur)},
  keywords = {{CHAMP} {MAGNETIQUE} ; {TERRE} ; {CONDUCTIVITE} ; {OBSERVATOIRE} ; {VARIATION} {TEMPORELLE} ; {VARIATION} {SECULAIRE} ; {VARIATION} {SPATIALE} ; {MODELISATION}},
  numero = {},
  pages = {145--157},
  booktitle = {{R}apport quadriennal 1995-1998},
  year = {1999},
  URL = {https://www.documentation.ird.fr/hor/fdi:010020073},
}