Abstract: Xth SCAR International Biology Symposium, Sapporo, Japon, 26-31/07/2009

Abstract: Xth SCAR International Biology Symposium", Sapporo (Japon), 26-31 juillet.

Abstract: Xth SCAR International
Biology Symposium. 26-31 Juillet 2009, Sapporo, Japan

Abstract: XIVth IAGA WORKSHOP ON GEOMAGNETIC OBSERVATORY INSTRUMENTS, DATA ACQUISITION AND PROCESSING; September 13 – 23, 2010; Changchun, Jilin Province, China.
The magnetic measurements at the Welschbruch Geophysical Station in Vosges (France) are disturbed by the passes of vehicles on the nearby road. The signing of these disturbances is clearly identified and reproducible. The vehicles are assumed to produce a dipolar field. Tests have shown that the magnetic dipole is not simply due to induced magnetization and hence has an unknown orientation, not parallel to the ambient magnetic field. A first model, parameterized by the time of passage, speed and dipole components, provides already a fairly good prediction of the observed signal. This prediction may be improved if a small amount of induction field, produced by the time varying vehicle disturbance, is introduced in the model, by means of an empirical induction matrix.

Abstract: XIVth IAGA WORKSHOP ON GEOMAGNETIC OBSERVATORY INSTRUMENTS, DATA ACQUISITION AND PROCESSING; September 13 – 23, 2010; Changchun, Jilin Province, China.
The K index was devised by Bartels et al. (1939) to provide an objective monitoring of the irregular geomagnetic activity, namely the magnetic signature of the solar wind and IMF effects on the Earth's magnetic field. It was then routinely used to monitor the magnetic activity at permanent magnetic observatories, as well as at temporary stations. The increasing number of digital and sometimes unmanned observatories and the creation of INTERMAGNET put the question of computer production of K at the centre of the debate. Four algorithms were selected during the Vienna meeting (1991), and endorsed by IAGA for computer production of K indices
To start with, we recall how geomagnetic data sampling may impact on computer-derived values of K-indices, and lead to underestimated values resulting in a statistical bias. We use one of the algorithms endorsed by IAGA, the so-called FMI algorithm developed by the Finnish Meteorological Institute, to investigate the impact of the geomagnetic data sampling interval on computer produced K values. We use this algorithm since it gives results that are fairly comparable to those hand-scaled on analogue magnetograms by an experienced observer.
The impact of the sampling interval on computer-produced K values is investigated through the comparison of the computer derived K values for the period 2009, January 1st to 2010, May 31 at the Port aux Français magnetic observatory using magnetic data series with different sampling rate (the smaller: 1 second; the larger 1 minute). The impact is investigated on both 3-hour range values and K indices data series, as a function of the activity level, for low and moderate geomagnetic activity (there was no intense magnetic storm during 2009, and very few during the first months of 2010).