A study of variations of galactic cosmic ray intensity based on a hybrid data-processing method

Discussion timeslot (ZOOM-Meeting): 16. July 2021 - 18:00
ZOOM-Meeting URL: https://icrc2021.desy.de/pf_access_abstracts
Corresponding Session: https://icrc2021-venue.desy.de/channel/Presenter-Forum-1-Evening-All-Categories/48
Abstract:
'The low energy cosmic-ray (CR) fluxes measured by space-borne instruments are rngenerally considered to consist of the gradually changing galactic cosmic rays rn(GCRs) and the short-lived solar energetic particles (SEPs). The SEP events cause the sharp and ephemeral increases in the time profile of CR observations with higher occurrence rate in solar maximum. It is necessary to eliminate such rnspikes and obtain the pure GCR component while studying the modulation of GCRs rnboth in short and long time scales. A hybrid data processing method based on rnspike detection and time series analysis techniques is developed to removernthe spikes and decompose the GCR data observed by the Interplanetary Monitoring rnPlatform 8 (IMP 8) into the long-term variation trend and the 27-day variation components. With the hybrid data processing method, the 11-year rnand 27-day variations in the intensity of low energy GCR can be studied rnsystematically. Using the fitted trend component, the time lag in solar modulation of low energy GCRs is studied, and the results show that the time lag is both epoch and energy dependent. The obtained 27-day variation component is anti-correlated with the changes in solar wind velocity even during solar maximum. Implementing the running Fourier series fit procedure, the 27-day rnvariation amplitude of proton flux is computed. It is found that the yearly averaged values show clearly 11- and 22-year variation cycles. In addition, rnthe energy spectrum of the 27-day variation amplitude is softer in $A smaller 0$ solar minimum than that in $A larger 0$ solar minimum.'

Authors: Zhenning Shen
Co-Authors: Qin Gang
Indico-ID: 727
Proceeding URL: https://pos.sissa.it/395/1343