Variations in the K-Index of Geomagnetic Activity in the Moscow Region

Resumo

We present the results of a statistical analysis of geomagnetic activity measured at the Mikhnevo Geophysical Observatory of the Institute of Geosphere Dynamics of the Russian Academy of Sciences (54.960° N; 37.774° E) located in Moscow region (central part of the Eastern European Platform) and its relation to the solar activity. We use the station geomagnetic K-index as a characteristic of the geomagnetic activity. We apply the results of instrumental observations of the geomagnetic field carried out at the Mikhnevo Geophysical Observatory from 2009 to 2015 to calculate the K-index using the method of adaptive smoothing. The geophysical situation of the Moscow region is characterized by a significant number of days with a disturbed state of the geomagnetic field (in the period analyzed here, magnetic storms were recorded in 181 cases and a disturbed geomagnetic situation was identified in 333 cases). At the same time, there is a tendency for an increase in geomagnetic activity with time: from 2009 to 2015, the number of days with disturbed geomagnetic conditions increased almost eight times. The recurrence of geomagnetic disturbances is characterized by clearly pronounced periodicity with characteristic periods of about 2 weeks, 27 and 60 days, half a year, and 1 year. The total duration of geomagnetic disturbances, which is characterized by K ≥ 4, varies significantly with time. The evaluation of the correlation between the total monthly number of geomagnetic disturbances characterized by a value of K ≥ 3 and the parameter determining the intensity of solar radio emissions (flux density) at a frequency of 2800 MHz (with a wavelength of 10.7 cm) (F 10.7) provide evidence about the significant correlation between the number of geomagnetic disturbances and solar activity.