Abstract:
X-Ray solar flare related Forbush decreases (Fds) observed during the period of solar cycle 23 and rising phase of 24 (2000-2012) have been studied with coronal mass ejections (CMEs) and disturbances in solar wind plasma parameters. It is observed that all the X-Class, X-ray solar flare related Forbush decreases (Fds) are associated with halo and partial halo coronal mass ejections (CMEs) and most of them (82.35%) have higher speed CMEs with speed >1000Km/s. Large positive correlation with correlation coefficient 0.68 has been found between magnitude of X-ray solar related Forbush decreases (Fds) and speed of associated CMEs. Further all these Forbush decreases (Fds) have been identified as being associated with disturbances in solar wind plasma parameters, (Temperature, Density, Velocity). Positive correlations with correlation coefficient 0.44 and 0.37 have been determined between magnitudes of X-Ray solar flare related Forbush decreases (Fds) and peak value and magnitude of associated disturbances in solar wind plasma temperature, 0.32 and 0.42 between magnitudes of X-Ray solar flare related Forbush decreases (Fds) and peak value and magnitude of associated disturbances in solar wind plasma density. Positive correlations with correlation coefficient 0.32 and 0.14 have also been determined between magnitudes of X-Ray solar flare related Forbush decreases (Fds) and peak value and magnitude of associated disturbances in solar wind plasma velocity.
Keywords: Forbush decreases (Fds), Coronal Mass Ejections (CMEs), Solar Wind Disturbances.
Deepti Shukla, Dr. Shiva Soni, Dr. Preetam Singh Gour