Abstract: published in Data Science Journal (part of the "Proceedings of the XIV
IAGA Workshop on Geomagnetic Observatory Instruments, Data Acquisition,
and Processing")
Abstract:
The K index was devised by Bartels et al. (1939) to provide an
objective monitoring of irregular geomagnetic activity. The K index 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 the computer production of K
indices. We used one of them (FMI algorithm) to investigate the impact
of the geomagnetic data sampling interval on computer produced K values
through the comparison of the computer derived K values for the period
2009, January 1st to 2010, May 31st at the Port-aux-Francais magnetic
observatory using magnetic data series with different sampling rates
(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.