geomagnetic activity at 19-24 cycles
Sumaruk Yu., Sumaruk P.
Institute of Geophysics National Academy of
Science of Ukraine, Kiev, Ukraine
instrumental observations at the magnetic observatories of INTERMAGNET
and the data of the international centers on solar–terrestrial
physics, geomagnetic and solar activities reached their maximums late
in the 1950s (Wmax = 190 in 1957). Subsequently, activities
Geomagnetic and solar activities were lower in cycle 20 (Wmax = 106 in
1964–1976) and were minimal during the growth phase of cycle 24
(Wmax = 62 in 2009–2013).
The GSMF value decreases at solar activity minimums.
Geomagnetic activity sharply decreases and lags behind solar activity
represented by Wolf numbers. The delay time decreases in the course of
time; in cycles 22 and 23, solar and geomagnetic activities developed
The abrupt decrease in geomagnetic activity in cycle 24 can be
explained as follows:
(a) the GSMF value decreases;
(b) the 200-year cycle minimum approaches (the minimum is anticipated
in 2050–2060 between cycles 25 and 27;
(c) activity develops at negative GSMF.