TY  - STD
AU  - Schott J.J.
PY  - 2007//
TI  - Progresses and challenges in magnetic observatory operation
N2  - The description of the recent progresses in ground based magnetic observatory operation encompassesseveral aspects: instrumentation, acquisition, accuracy estimation, data processing, data transmission, opening of new observatories. In the present state of the art, manual absolute measurements remain the most accurate way of controlling the base lines of the magnetometers, whatever their type. Their obvious drawback is that the observatories have to be operated by a trained observer. This condition may be difficult to fulfil in remote areas. In addition, economic pressure may result in a reduction of the observer staffs. Efforts are made for several years towards more automatization of the absolute measurements. Two recently proposed solutions (Rasson and Van Loo, one one hand, Auster et al. on the other hand) will be discussed. Both solutions, however, still need the presence of an observer. The most elegant way of solving the problem would be to imagine continuous recording absolute magnetometers. An idea, originally proposed by Alldredge (1960) led to the development of the DIDD instrument (Hegymegi, Krmendi). Although many improvements were brought to the successive versions, it still requires manual base line controls. In addition, the instrumental reference frame is not easy to determine. More recently, a new concept was implemented, based upon the modulation of the signal of an optical pumping magnetometer by two orthogonal coils (Gavrand et al.,2001 ). Although it should be more stable than the DIDD system, similar problems arise with the orientation of the instrument. Numerical acquisition, based upon some kind of data logger, is now the standard, the typical reference being the Intermagnet network. Currently, concerns focus on resolution, sampling rate and time stamp. These issues become particularly crucial with the solicitation for moving towards subminute – typically one second- sampling rates. Worldwide synchronized one second data (in addition properly filtered) acquisition and dissemination will probably be a big challenge for the next future. Even data processing and accuracy estimation for the current one minute sampling rate have not yet reached their mature estate. Efforts have still to be made towards a more homogeneous processing protocol and accuracy estimation based upon safe statistical methods. The last issue includes sensor orientation and calibration aspects. Various calibration methods are regularly suggested but the sensor orientationproblem is probably underestimated. Finally, we will evoke the efforts made towards a more homogeneous worldwide distribution of ground-based observatories with a particular emphasis on observatories opened or planned in remote areas. However, it is obvious that due to the poor distribution of emerged lands, this endeavor will remain limited. Extending the netword to ocean bottom observatories could be an exciting challenge for the next future, although technically difficult and financially demanding.
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ID  - SchottJ.J.2007
ER  -