VLF Emissions and Geomagnetic Disturbances at the Auroral Zone

Part II Chorus Increases and Geomagnetic Pulsations at the Auroral Zone

Abstract

A close relation has been found between increases of chorus indices continuing for a few hours and geomagnetic pulsations at the auroral zone, using the chorus indices and rapid-run magnetograms at College, Alaska, during July, 1959 to December, 1960.
During this period 79 increases of chorus indices occurred in relatively quiet geomagnetic-conditions after geomagnetic bay-like disturbances. Of 79 chorus increases, 52 were associated with geomagnetic pulsations with periods between 1 and 6 minutes and 11 were associated with pulsations having periods of about 30 seconds.
The chorus increases may be generated by penetration of high speed charged particles into the exosphere, which may also be related to the geomagnetic pulsations.
A possible mechanism of the generation of geomagnetic pulsation has been discussed.