The two flares of 19 and 30 July 1999 were observed in the H a line using the multichannel flare spectrograph (MFS) at the Astronomical Institute in Ondrˇejov, Czech Republic. We use a modified cloud method to fit the H a line profiles which avoids using the background profile. We obtain the four parameters of the two flares: the source function, the optical thickness at line center, the line-of-sight velocity and the Doppler width. The observed asymmetry profiles have been reproduced by the theoretical ones based on our model. A discussion is made about the results of strong and weak flares using the present method.
The relations between sunspot number, sunspot areas, and solar 10.7 cm radio flux, solar proton events and earthquakes of magnitude M ≥ 5 and M ≥ 8 during the interval from 1996 to 2008 of the solar cycle 23 have been analyzed in this work. We have found that there is a direct relation between solar activity and Earth seismic activity for M ≥ 5 and M ≥ 8, near the maximum of the solar cycle 23, and an inverse relation between them at the descending phase of the cycle.
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