Recognition of disturbances with specified morphology in time series. Part 1: Spikes on magnetograms of the worldwide INTERMAGNET network |
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| Authors: | Sh R Bogoutdinov A D Gvishiani S M Agayan A A Solovyev E Kin |
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| Institution: | 1.Geophysical Center,Russian Academy of Sciences,Moscow,Russia;2.National Geophysical Data Center,National Oceanic and Atmospheric Administration,Boulder,USA |
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| Abstract: | The International Real-time Magnetic Observatory Network (INTERMAGNET) is the world’s biggest international network of ground-based
observatories, providing geomagnetic data almost in real time (within 72 hours of collection) Kerridge, 2001]. The observation
data are rapidly transferred by the observatories participating in the program to regional Geomagnetic Information Nodes (GINs),
which carry out a global exchange of data and process the results. The observations of the main (core) magnetic field of the
Earth and its study are one of the key problems of geophysics. The INTERMAGNET system is the basis of monitoring the state
of the Earth’s magnetic field; therefore, the information provided by the system is required to be very reliable. Despite
the rigid high-quality standard of the recording devices, they are subject to external effects that affect the quality of
the records. Therefore, an objective and formalized recognition with the subsequent remedy of the anomalies (artifacts) that
occur on the records is an important task. Expanding on the ideas of Agayan Agayan et al., 2005] and Gvishiani Gvishiani
et al., 2008a; 2008b], this paper suggests a new algorithm of automatic recognition of anomalies with specified morphology,
capable of identifying both physically- and anthropogenically-derived spikes on the magnetograms. The algorithm is constructed
using fuzzy logic and, as such, is highly adaptive and universal. The developed algorithmic system formalizes the work of
the expert-interpreter in terms of artificial intelligence. This ensures identical processing of large data arrays, almost
unattainable manually. Besides the algorithm, the paper also reports on the application of the developed algorithmic system
for identifying spikes at the INTERMAGNET observatories. The main achievement of the work is the creation of an algorithm
permitting the almost unmanned extraction of spike-free (definitive) magnetograms from preliminary records. This automated
system is developed for the first time with the application of fuzzy logic system for geomagnetic measurements. It is important
to note that the recognition of time disturbances is formalized and identical. The algorithm presented here appreciably increases
the reliability of spike-free INTERMAGNET magnetograms, thus increasing the objectivity of our knowledge of the Earth’s magnetic
field. At the same time, the created system can accomplish identical, formalized, and retrospective analysis of large archives
of digital and digitized magnetograms, accumulated in the system of Worldwide Data Centers. The relevant project has already
been initiated as a collaborative initiative of the Worldwide Data Center at Geophysical Center (Russian Academy of Sciences)
and the NOAA National Geophysical Data Center (Unite States). Thus, by improving and adding objectivity to both new and historical
initial data, the developed algorithmic system may contribute appreciably to improving our understanding of the Earth’s magnetic
field. |
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