Time Delay of the Substorm Onset from the IMF Southward Turning

Abstract

The time delay of the substorm onset defined by the onset of the earliest Pi2 magnetic pulsations from a southward turning of the north-south component of the interplanetary magnetic field (IMF-Uz) has been investigated for 21 characteristic IMF events. It was found that the time delay had little dependence on the intensity of the IMF southward component in the range of the intensity examined (i.e. from —1.5 to — 9 nT), or rather it was constant (about 1 hr) except for a few cases. This result suggests that the time delay can be interpreted as a response time inherent in the magnetosphere. © 1980, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.