Coronal mass ejections (CMEs) are the major space-weather transients with large magnetic field structures. They have a typical size of 0.3 AU by the time they reach the Earth. Considering the conventional solar modulation concept, we expect a decrease in the cosmic ray intensity observed at the Earth during the passage of a CME. In this talk, I shall discuss two occasions when we saw an unusual increase in cosmic ray intensity observed at ground-based cosmic ray detectors. Both these occasions were unique, the CMEs associated with them having different natures. One was associated with a fast-moving CME with a very strong shock, while the other was a slow CME with a weaker shock. I will explain how cosmic ray observations have provided detailed pieces of information about these solar transient events and their effects on our near-Earth environment.
|