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Solar and geomagnetic activity at 19-24 cycles |
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Sumaruk Yu., Sumaruk P. |
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Institute of Geophysics National Academy of Science of Ukraine, Kiev, Ukraine |
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According to 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 spasmodically decreased. 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 in phase. 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. |
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oral |