Assessment of Planetary Indices of Geomagnetic Activity Based on Data from Individual Magnetic Observatories in the Russian Sector

The K index was devised by Bartels et al. (1939) to provide an objective monitoring of irregular geomagnetic activity at subauroral latitudes. K indices are based upon geomagnetic disturbances, measured in horizontal geomagnetic components at magnetic observatories, after &#171; eliminating &#187; the regular daily variation. An individual K index is an integer in the range 0 to 9 corresponding to a class that contains the largest range of geomagnetic disturbances (in either of the two horizontal components) during a 3-hour UT interval. Limits of range vary from one observatory to another since they depend on the corrected geomagnetic latitude of the observatory.A great number of Space Weather applications rely on K-derived magnetic activity indices at subauroral latitudes. These historical indices; endorsed by IAGA such as Kp, aa and am; represent unprecedented homogeneous time series, up to more than 150 years, highly valuable for all studies related to long-term geomagnetic activity.However, one has to keep in mind that local K indices and subauroral related ones (K-derived) were developed during other time, under specific societal and technological conditions.We recall the local K indices derivation processes and characteristics to enlight possible nowadays drawbacks and their simple mitigations.

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On the semiannual and annual variations of geomagnetic activity and components

Annales Geophysicae ◽

10.5194/angeo-22-3583-2004 ◽

2004 ◽

Vol 22 (10) ◽

pp. 3583-3588 ◽

Cited By ~ 15

Author(s):

J.-L. Le Mouël ◽

E. Blanter ◽

A. Chulliat ◽

M. Shnirman

Keyword(s):

Time Scales ◽

Geomagnetic Activity ◽

Activity Index ◽

Magnetic Activity ◽

Amplitude Ratios ◽

Time Constants ◽

Annual Variations ◽

Geographical Variability ◽

Semiannual Variation ◽

Magnetic Observatories

Abstract. The semiannual and annual lines in a long series of magnetic observatories daily values, as well as in the aa-activity index series, are investigated. For both periods, amplitudes and phases of the lines corresponding to the different series present grossly common variations on decadal time scales; relative phases and amplitude ratios between the observatories change with the same time constants. The results are briefly discussed with regards to commonly received theories of the semiannual variation of magnetic activity, and some possible mechanisms for the observed geographical variability are suggested.

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Recovering of local magnetic K-indices from global magnetic Kp-indices using neural networks: an application to Antarctica

Annals of Geophysics ◽

10.4401/ag-6719 ◽

2015 ◽

Vol 58 (4) ◽

Author(s):

Antoni Segarra ◽

Juan José Curto

Keyword(s):

Neural Networks ◽

Geomagnetic Activity ◽

Specific Area ◽

Global Index ◽

Local Index ◽

Global Indices ◽

K Index ◽

Major Interest ◽

Processing Information ◽

Magnetic Observatories

This paper describes a method to obtain local magnetic index, K, from the global index, Kp. Until now, however, for the cases of areas without magnetic observatories, to estimate the geomagnetic activity there, global indices were the only option. The methodology that we used to estimate local index was based on neural networks. This tool has a great potential for processing information from complex systems as in the case of the geomagnetic system. Local K index calculated with this method resulted to be a better option than directly using the global index Kp when we need an indicator of geomagnetic activity in a specific area. The best results of our method were for moderate and high geomagnetic activity, which are of major interest in Space Weather.

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