Power spectra analysis for interplanetary high energetic charged particles measured by GOES from January 1987 to June 1998

The proton fluence in the interplanetary medium is measured by GOES of NASA at three different energetic levels as >1 Mev, >10 MeV, and >100 MeV. The data for the period (January 1987-June 1998) are published in “Solar Geophysical Data” of NOAA, Boulder, Colorado, USA. The data are provided merely as a tool to distinguish when events occur. Where, during the period of January 1987-June 1998 more than seventy solar proton events affecting the Earth environment are recorded by the GOES Spacecraft at geosynchronous orbit, for energies >10 MeV. Also, in 22 March 1991 during the declining phase of solar cycle 22, a very high energetic solar proton flare was released at UT 22 h 47 m from NOAA/SESC active region No. 6555. The proton flux of particles had energies >10 MeV was 43,000 particle flux units (pfu), measured by GOES spacecraft. It is the highest measured one during the solar cycle 21 and 22. The power spectra analysis are applied on the time series of the daily proton fluence measured by GOES for the period (January 1987-June 1998) for the three energetic levels. The results show a variability in the proton fluence as short and long-term periodicities close to the periodicities of the solar activity