Periodicities of Sunspot Number and Coronal Index Time Series During Solar Cycle 23 |
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| Authors: | Chowdhury Partha Dwivedi B N |
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| Institution: | (1) Kandilli Observatory and Earthquake Research Institute Çengelköy, Bo aziçi University, 81220 Istanbul, Turkey |
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| Abstract: | We investigate the presence and temporal evolution of short- and intermediate-term periodicities in the daily data of sunspot
numbers and coronal index for the time span from May 1996 to December 2008, which covers the entire Solar Cycle 23. The daily
sunspot number data have been analyzed for the full disk, and for northern and southern hemispheres of the Sun. Using the
wavelet power spectrum technique, we find a number of quasi-periodic oscillations in all the data sets. We also find a prominent
period of 22 to 35 days in the high-frequency range, and detect the Rieger period of 150 to 160 days in both data sets during
different phases of Cycle 23. We also detect ∼1.3 year oscillation in both sunspot and coronal index time series. In addition,
we find a number of other short and mid-term periods. We discuss possible explanations of the observed periodicities in the
light of previous results and existing numerical models. |
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