Forbush Effects Created by Coronal Mass Ejections with Magnetic Clouds

In this paper, we study the effect of magnetic clouds on variations in the cosmic ray density recorded by neutron monitors. The statistical patterns and characteristic features of such events are distinguished from data on 252 Forbush effects caused by interplanetary disturbances containing magnetic clouds. The behavior of the main parameters of solar wind, cosmic rays, and geomagnetic activity during the passage of magnetic clouds past the Earth, as well as the characteristic features of the internal structure of magnetic clouds, are discussed. It is shown that the cosmic ray variations are closely related to the maximal parameters of the solar wind and the interplanetary magnetic field inside the magnetic clouds. It is established that the maximal velocity inside the magnetic cloud is most often registered at the beginning of the event, while the maximal value of the interplanetary magnetic field is registered both at the beginning and in the middle of the event by the time distribution of the solar wind maximal parameters. It is also found that there is a sufficiently close correlation of the variations of cosmic ray density in a magnetic cloud with its size expressed in the hyroradii.