Forbush decrease observed by SEVAN particle detector network on November 4, 2021

TL;DR

This study reports the detection of a Forbush decrease by the SEVAN network during a 2021 geomagnetic storm, comparing measurements across multiple locations and analyzing associated electric and magnetic disturbances.

Contribution

It provides a multi-site comparison of Forbush decrease measurements and analyzes near-surface electric and geomagnetic field disturbances during a significant space weather event.

Findings

Detected a 5-10% Forbush decrease across multiple SEVAN sites.

Compared measurements at mountain and sea level locations.

Observed disturbances in electric and geomagnetic fields at ICME arrival.

Abstract

On November 3-4 2021, an interplanetary coronal mass injection (ICME) hits the magnetosphere, sparking a strong G3-class geomagnetic storm and auroras as far south as California and New Mexico. All detectors of the SEVAN network registered a Forbush decrease (FD) of 5-10 percentdeep in 1 minute time series of count rates. We present the results of a comparison of Fd registered on mountain altitudes on Aragats (Armenia), Lomnicky Stit (Slovakia), Musala (Bulgaria), and at sea level DESY (Hamburg, Germany), and in Mileshovka, Czechia. We present as well purity and barometric coefficients of different coincidences of SEVAN detector layers on Aragats. We demonstrate disturbances of the near-surface electric (NSEF) and geomagnetic fields at the arrival of the ICME on Earth.