TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 62 (No. 2), pp. e5-e8, 2010


On the feasibility of promptly producing quasi-definitive magnetic observatory data

Aline Peltier1 and Arnaud Chulliat2

1Laboratoire Géologie des Systémes Volcaniques, Institut de Physique du Globe de Paris, CNRS, UMR 7154, 4 place Jussieu, France
2Laboratoire de Géomagnetisme, Institut de Physique du Globe de Paris, CNRS, UMR 7154, 4 place Jussieu, France

(Received December 1, 2009; Revised January 29, 2010; Accepted February 3, 2010; Online published February 22, 2010)

Abstract: Magnetic observatories currently distribute two types of data: preliminary data, available in less than 72 hrs in the case of INTERMAGNET observatories, and definitive baseline-corrected data, produced only once a year. Several users and groups of users have expressed the need for baseline-corrected observatory data produced in a continuous manner. The main applications for such quasi-definitive data include geomagnetic field modeling and the calculation of geomagnetic activity indices. We present an original method for producing quasi-definitive data at the end of each calendar month using temporary baselines. Preliminary and definitive data at nine INTERMAGNET observatories are used to test this method, simulating the production of quasi-definitive data throughout the year 2008. The temporary baselines obtained are very close to the definitive ones, except during the last few days of each time interval. The means and standard deviations of the differences between quasi-definitive and definitive data do not exceed 0.3 nT, well below the current INTERMAGNET standard of accuracy. This result demonstrates the feasibility of promptly producing quasi-definitive data at most magnetic observatories of INTERMAGNET type.
Key words: Magnetic observatory, geomagnetic modeling, baseline, data processing, quasi-definitive data.

Corresponding author E-mail: peltier@ipgp.fr

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