It is believed that the physical mechanism responsible for the transference of energy from the solar wind to the Earth magnetosphere is the reconnection between the interplanetary magnetic field and the terrestrial magnetic field (Tsurutani & Gonzalez, 1997). The necessary criterion for a Intense Geomagnetic Storms to occur, Dst < -100nT, is the existence of a dawn-dusk interplanetary electric field larger than 5 mV/m, for a period larger than 3 hours. Cosmic rays have been studied as a natural phenomenon that can tell us much about both Earth's environment in space and distant astrophysical processes (Jokipii, 2000). A solar disturbance propagating away from the Sun affects the pre-existing population of galactic cosmic rays in a number of ways. The most famous one is known as the "Forbush decrease", which is a supression of ground cosmic-ray counts observed during Geomagnetic Disturbances. The objective of this work is to study the response of the Southern Space Observatory - SSO ground Muon Telescope observations, installed in São Martinho da Serra, RS, Brazil, to 3 super intense geomagnetic storms, combining observation provided by L1 satellites and ground detectors.
interplanetary medium; cosmic rays; Muon Telescope; Forbush decreases; space weather; magnetic storms
