Yakutsk, Russian Federation
The paper considers changes in the daily average values of the Dst, SYM-H, ASY-H, and ASY-D indices and their dependence on the level of magnetic disturbance for the period 1981–2016. These indices are geomagnetic characteristics of the magnetospheric ring current. It has been established that the indices of the asymmetric component of the ring current ASY-H and ASY-D during relatively magnetically quiet periods are not equal to zero. The values of the offsets in the dependences of the ASY-H and ASY-D indices on the level of magnetic disturbance have been determined. The behavior of the index of the degree of symmetry of the ring current, the ratio SYM-H / ASY-H, is analyzed during the year at different levels of disturbance. This ratio has been found to grow in absolute value with increasing disturbance and to exceed 1 at large disturbances (at Dst <–50).
geomagnetic index Dst, geomagnetic indices SYM and ASY, magnetospheric ring current
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