Overview of the Solar Activity During Solar Cycle 23

ISSN： 0038-0938

Source： Solar Physics, Vol.233, Iss.1, 2006-01, pp. : 139-153

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Abstract

A brief description and final results of the flare index and some other indices of solar activity for cycle 23 from January 1, 1996 to December 31, 2003 are given. It is found that there is enough evidence to support that the present cycle is magnetically weak. The patterns of similar activity indices that arise under different physical conditions during cycle 23 were compared with the flare index. The photospheric magnetic flux and flare activity show very low values at the maximum of cycle 23 compared with the maximum phase of cycle 22. The major flare production during this cycle is very low while the quiet geomagnetic conditions are remarkably high during the rising and the maximum phase of the current cycle. The north–south asymmetry of CMEs, sunspot number, sunspot area, and flare index were studied. N–S asymmetry had increased in favor of the southern hemisphere for solar cycle 23 after the inverse polarities were installed. The intermediate-term periodicities in the daily flare index data for the northern and the southern hemispheres and full disc were calculated using the Fourier transform, and it was found that 64, 83, and 125 days periodicities are in operation during the maximum phase of the solar cycle 23.