Study of the recovery characteristics of intense cosmic-ray decreases

We study the recovery characteristics of large-amplitude cosmic-ray decreases by utilizing the ground based neutron monitor observations. We divide large-amplitude cosmic-ray transient decreases (called Forbush decreases) in the galactic cosmic-ray intensity into different groups based on their decrease time and recovery time. We apply an exponential fit to the recovery profile of Forbush decreases after obtaining the average profile for different groups using superposed epoch analysis. After a similar superposed epoch analysis of the three selected interplanetary plasma and interplanetary magnetic field parameters, we apply exponential fit on the decay time profile of these parameters, during recovery the of Forbush decreases. We compare the characteristics of interplanetary plasma and field parameters with the characteristics of Forbush decreases during its recovery phase. We isolate the interplanetary plasma field parameters whose characteristic decay time best-fits the characteristic recovery time of Forbush decrease. Our results suggest that the decay rate of the solar wind plasma speed is best related to the recovery rate of the Forbush decrease.