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Statistical characterisation of full-disk EUV/XUV solar irradiance and correlation with solar activity

J. Greenhough·S. C. Chapman·R. O. Dendy·V. M. Nakariakov·G. Rowlands
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Abstract

We investigate the distribution of fluctuations in solar irradiance when integrated over the full disk, obtained using extreme ultraviolet/soft X-ray observations from the SOHO CELIAS/SEM instrument. This time series sums over both the contributions of single distinguishable flares, and of many other processes. By detrending we select events with timescales of less than a few hours such as waves, slow flows, and CMEs. The statistics generated by this range of phenomena can be characterised by power-law-tailed distributions. We show that (i) during the high-activity period 2000 Jan-June the tail exponent a(T)=1.5 +/- 0.1; (ii) during the low-activity period 1996 Jan-June a(T)=3.0 +/- 0.2; and (iii) in general a(T) decreases with increasing activity.

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J. Greenhough, S. C. Chapman, R. O. Dendy, V. M. Nakariakov, G. Rowlands. 2003-07-28. Statistical characterisation of full-disk EUV/XUV solar irradiance and correlation with solar activity. https://doi.org/10.1051/0004-6361%3A20031292

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