SIMULTANEOUS ELECTRIC AND MAGNETIC-FIELD OBSERVATIONS OF PCL-2, AND PC3 PULSATIONS

This paper presents results from a combined analysis of ULF fluctuatio ns in the geoelectric and geomagnetic fields. Data were obtained at So uth Pole station during the 1985-1986 South Pole Balloon Campaign. Mag netic field perturbations were measured by the two-axis induction or ' 'search coil'' magnetometer at South Pole station. Vector electric fie ld data were obtained by a standard double-probe experiment on the bal loon payloads. The objective of this study is to investigate the relat ionship between the electric and the magnetic components of geomagneti c micropulsations in the Pc1-3 frequency bands (0.01 to 0.5 Hx). The e ntire 468-hour database of the balloon campaign has been searched for examples of strong discrete magnetic micropulsation emissions in these bands. The two best days were found to be January 7 and 8, 1986. Two emissions were seen on both days, a Pc3 emission between 30 and 40 mHz that extended for about 3 hours on either side of magnetic noon and a Pc1-2 emission that started around magnetic noon and lasted for sever al hours. The amplitude histories of the emissions were found to be ro ughly comparable when account was taken of the effect of varying preci pitation on the ionospheric conductivity. The two components of the ma gnetic field did not show significant coherence. Consequently, little coherence was expected or found between the electric and magnetic comp onents. An ionospheric transmission model has been used to interpret t he observed BIE ratio in terms of the horizontal wave number of the so urce. The wave number that was inferred for the Pc3 emissions implies a phase speed roughly equal to the phase speed of simultaneous traveli ng convection vortex events.