| Vol. 27, Issue 5 |
Ahluwalia [617] examines changes in the rigidity (which is related to energy spectra) of galactic cosmic rays over three solar cycles. The rigidity is shown to be correlated with the magnitude of the interplanetary magnetic field (IMF) but not with the fluctuations within the IMF. It is also shown to be correlated with the planetary index Ap, which could be used as a proxy for the IMF if no in situ data are available. This work helps us understand heliospheric energy transport. Clack et al. [625] show in two examples of corotating interaction regions (CIRs) that the magnetic field vectors within them are closely confined to a plane that reflects the global orientation of the interaction region. The CIRs were observed in opposite solar hemispheres by the Ulysses spacecraft in 1992 and 1993 and in 1996 and 1997. The authors use the spacecraft's magnetic field measurements to infer the three-dimensional structure and orientation of CIRs. The CIRs contain planar magnetic structures, on small and large scales, which are oppositely tilted in the northern and southern hemispheres. On 24 September 1998, a large-scale solar wind discontinuity arrived at the Earth's magnetosphere. The associated magnetic storm reached its maximum the next day. Chi et al. [633] use the gradient technique of magnetic pulsations, applied to data from two U.S. ground magnetometer stations, to provide remote sensing for density variations of the plasmasphere under the storm's influence. They find a significant depletion of the density during the recovery phase of the storm, and they attribute this plasmaspheric erosion to convection stirred up by the electric field associated with the storm. |
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