Abstract: EGU General Assembly, poster, Abstract EGU2009-8637

Abstract: Seabird Group 10th International Conference

Abstract: The description of the recent progresses in ground based magnetic observatory operation encompasses
several 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 orientation
problem 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.

Abstract: EGU, April 2007, Vienne (AT).

Abstract: We have presented here the results of a statistical study of two polar magnetic indices, computed from data from two near-pole geomagnetic observatories: Thule in the northern hemisphere and new, Concordia (Dome C) observatory near the southern geomagnetic pole in Antarctica. We found that:
The northern PMn and southern PMs polar magnetic indices show a good correlation with the solar wind/IMF parameters (the average correlation coefficient is ~ 0.87). Meanwhile, the southern PMs index shows a significantly better correlation than the northern PMn index, which demonstrates that the new Concordia observatory may play an important role in improving the Space Weather prediction.
The obtained results also show a high correlation between these two polar magnetic indices: the average correlation coefficient for this period was ~0.9 while for equinoctial months it increased up to 0.94-0.96.
Using the polar magnetic indices in two hemispheres may also significantly improve the prediction of other parameters, including the auroral electrojet AL index which shows substorm activity. Using the polar magnetic indices in two hemispheres allows us to predict the auroral electrojet AL index with a very high reliability (the correlation coefficient between predicted and actual AL indices is ~0.9, while for the equinoctial months the correlation coefficient was ~0.92).
The results of this study show an important role which is played by the magnetic disturbances in both polar ionospheres in developing the global magnetic activity, and the necessity to account for the magnetic disturbances in both ionospheres for improving the Space Weather prediction in the Geospace environment.