Investigating the Role of Solar-geomagnetic Parameters on Fully-automated Forbush decrease Events

The abrupt reductions in the time-intensity flux of galactic cosmic rays (CRs), known as Forbush decreases (Fds) are widely regarded as reliable indicators of space weather disturbances driven by solar tran-sients such as coronal mass ejections. However, accurately detecting these signals poses a challenge when studying Sun-Earth-related phenomena, leading to the creation of various FD catalogs in the literature. In this paper, we analyze daily-averaged CR data from three neutron monitor (NM) stations located at altitudes above 1100 meters-Climax (CLMX), Calgary (CALG), and Emiliosegre (ESOI) over the period from 1999 to 2006. Hourly CR data were used to validate the results. Using the most precise FD detection method, we identified 205, 54, and 97 FDs with magnitudes of CR(%) > 3 reductions from the CALG, CLMX, and ESOI NM stations, respectively. We compared the catalogs of these large-magnitude FDs to assess the sensitivity of the NM stations. Besides large FDs, a sub-routine of the FD detection program equally searched for small FDs (CR(%) ≤ 3) at these three stations. Totals of 97, 248, and 247 small-amplitude FDs were detected at CALG, CLMX, and ESOI respectively. Since the fully automated method (FAM) employed in the current work statistically identifies FDs, the catalogs of Forbush events presented in the current work may contain recurrent and non-recurrent events. However, event-by-event examination is needed to classify them. Additionally, we identified 30 large FD events that happened simultaneously at the three stations. For these 30 simultaneous FDs, the average event magnitudes were-26.14%,-6.03%, and-8.08% for the CALG, CLMX, and ESOI stations, respectively. Correlation/regression results indicate highly statistically significant relations at the 95% confidence level between solar-geomagnetic variables and CR flux intensity. The catalogs of FDs used in this study are more accurate than some existing FD lists derived directly from cosmic ray raw data without accounting for the influence of the 11-year solar cycles, making them potentially valuable for researchers investigating solar-climate connections.