| Abstract: | The solar irradiance data plays a very important role for understanding of Solar internal Structure and the solar terrestrial
relationships. The Total Solar Irradiance (TSI) is integrated solar energy flux over the entire spectrum which arrives at
the top of the atmosphere at the mean sun earth distance. TSI has been monitored from several satellites, e.g. Nimbus 7, Solar
Maximum Mission (SMM), The NASA, Earth Radiation Budget Satellite (ERBS), NOAA9, NOAA10, Eureca and the Upper Atmospheric
Research Satellite (UARS) etc. From these observations it reveals that the total solar irradiance varies about a small fraction
of 0.1 over solar cycle being higher during maximum solar activity condition. In the present paper we have analysed the solar
irradiance data from ERBS during the time period from October 15, 1984 to October 15, 2003. First filtering the data by Simple
Exponential Smoothing we have applied the Rayleigh Power Spectrum Analysis on the processed data in order to search for its
time variation. Study exhibits multi-periodicities on these data around 7, 11, 42, 80, 104, 130, 160, 254, 536, 752, 1142,
1388, 2474 and 4951 days with very high confidence levels (more than 95%). Apart from these strong periods there are some
other weak periods around 22, 47, 53, 67, 69, 149, 167, 365, 489 and 683 days. These periods are significantly similar with
the periods of other solar activities which may suggest that solar irradiance may be associated with other solar activities. |
