Characteristics of VLF Emission during SSC : A Preliminary Report on SSC Effect on 21st September 1977

Abstract

SSC on 21st September 1977 is found to have given impact to VLF emission source in the magnetosphere and also to a power line system on the ground. A new feature of SSC effects to VLF emission was obtained on the basis of direction-finding technique for VLF waves, and revealed that the emission zone in the north expands southward during the rising phase of the SSC, adding to the known SSC effects, increases in average frequency, band width and integrated power of VLF emission Power line harmonic noise, specifically in even harmonics, increased prommently and oscillated correlated with geomagnetic pulsation after the SSC. This phenomenon is explained as the result of wave distortion effect in transformers in a power line system when the electric current originated to the earth current induced at the time of the SSC flowed through a pair of neutral points of the transformers grounded to the earth.