Processes in the quiet and disturbed equatorial-low latitude ionosphere: Sundial campaign, 1984

Abstract

A network of ionospheric diagnostic instruments was operated on a world wide basis during the October 5-13. 1984 SUNDIAL campaign. The network provided a unique opportunity for a truly multiple technique global analysis of the equatorial-low latitude ionospheric behavior during the campaign period. The SUNDIAL equatorial-low latitude data set included electric field and spread F data from Jicamarca radar, ionosonde data from 15 stations and magnetograms from 5 stations operated in the American, African, Asian and Indian sectors. Also included are data from electronic polarimeters at 8razilian low-latitude sites. The data analysis has focused attention on the global scale steady state ionospheric behavior and its predictability by global theoretical model of Sojka and Schunk (1985) and by the lnternational Reference lonospheric (IRI). The results are suggestive of the need to modify existing quiet time electric field and neutral wind models in varying degrees for different longitude sectors. The analysis also concerns global scale ionospheric transient behavior in response to exo-ionospheric variabilities under disturbed conditions, in an approach towards a hotter understanding of the factors that effect short-term prediction schemes. Among the important outcomes of this study is the possibility of using longitude chains of equatorial region ionosondes (and magnetometers) for investigation of equatorial ionospheric response to magnetospheric electric field penetration events and disturbance dynamo effects.