Pulsing hiss, pulsating aurora and micropulsations

Simultaneous conjugate observations between the GEOS 2 geostationary satellite, an all-sky TV camera operated at Andenes, Norway and a magnetometer at Tromsø, are presented. A close correlation was found between the occurrence of pulsing ELF hiss on GEOS 2, pulsating aurora observed with the TV camera and the ground detected micropulsations. However, a one-to-one correlation between the individual pulses of all three phenomena was generally not found. Ten events were chosen for a case study where the optical pulsations could be classed into two types (either classical pulsating patches or propagating forms). Classical pulsations were seen to be associated with Pi( b) micropulsations while propagating forms showed a one-to-one correlation with Pi( c) micropulsations. Type matching between the optical pulsations and two different types of ELF hiss, agreed well on a statistical basis, but the exact relationship for individual events was not so clear. On occasions, the micropulsations possessed major frequency components whose periods were longer than the periods of the other two phenomena. This is shown to imply that the observed micropulsations were of ionospheric origin in these cases.