Properties of Forbush Decreases with AMS-02 Daily Proton Flux Data

Abstract

A Forbush decrease (FD) is a sudden reduction of Galactic Cosmic Rays (GCRs) that is usually caused by intense solar wind transients, such as Interplanetary Coronal Mass Ejections (ICMEs) and Corotating Interaction Regions (CIRs). Using daily proton fluxes measured by AMS-02 between 2011 May and 2019 October, we identified 142 FD events with an automatic systematic analysis method. The properties of 47 FDs caused by ICMEs and of 54 FDs caused by CIRs were analyzed. We found that the rigidity dependence of the GCR flux decrease is generally better described by an exponential function for both ICME and CIR FDs. We also found that the FD Amplitude of ICME FDs has a moderate correlation with the minimum Dst index and a number of solar wind parameters, such as maximum temperature, pressure, and magnetic field. For CIR FD events, neither FD Amplitude nor Maximum Affected Rigidity had a significant correlation with solar wind parameters.

Effects of Forbush Decreases on the Global Electric Circuit

“…We correlate the PG data with FD measurements examined in Wang et al (2023). Recently Wang et al (2023) examined FDs using AMS-02 observations onboard ISS.…”

“…We correlate the PG data with FD measurements examined in Wang et al (2023). Recently Wang et al (2023) examined FDs using AMS-02 observations onboard ISS. Unlike previous studies that using neutron monitor data on the Earth's surface, the study of Wang et al (2023) used daily proton flux data from the AMS-02 instrument to identify and classify 142 FD events between May 2011 and October 2019.…”

“…Recently Wang et al (2023) examined FDs using AMS-02 observations onboard ISS. Unlike previous studies that using neutron monitor data on the Earth's surface, the study of Wang et al (2023) used daily proton flux data from the AMS-02 instrument to identify and classify 142 FD events between May 2011 and October 2019. Since the orbit of ISS is at an altitude of ∼370-460 km, the FDs observed in Wang et al (2023) are in the ionosphere.…”

“…In recent years, a number of space-born detectors have obtained direct measurements of primary cosmic-ray spectra in space. Wang et al (2023) used daily proton data, measured by the Alpha Magnetic Spectrometer (AMS-02) on the International Space Station, to study the rigidity dependence of a large number of FD events. Alania and Wawrzynczak (2008) had earlier examined possible rigidity dependence of FDs.…”

“…It therefore can cause uncertainty and ambiguity of the classification of FDs. This ambiguity can be partially removed if one uses data of primary cosmic rays from, for example, the AMS-02 measurement onboard ISS, as done in Wang et al (2023). In this work, we examine how the variations of primary cosmic ray intensity affects the GEC by using the amplitude reduction parameter proposed and computed in Wang et al (2023).…”