The Effects of Magnetic Storm Phases on F-Layer Irregularities from Auroral to Equatorial Latitudes

Determining the morphology of F layer irregularities as a function of longitude in the equatorial region is vital for understanding the physics of the development of these irregularities. We aim to lay the observational basis which then can be used to test theoretical models. Theoretical models have been developed, notably in the papers by R.T. Tsunoda Rev. Geophys. 26, 719, 1988 and by T. Maruyama and N. Matuura J. Geophys. Res. 89, 10903, 1984. The question is whether the models are consistent with the morphology as we see it. According to our criteria, the data used should be confined to observations taken near the magnetic equator during quiet magnetic periods and at times within a few hours after sunset. Anomaly region data should be omitted for studying the generation mechanism. The questions to be answered by proposed mechanisms are 1 why do the equinox months have high levels of occurrence over all longitudes 2 why are there relatively high levels of occurrence in the Central Pacific Sector in the July-August period and in the 0-75 deg West Sector in the November-December period 3 why are there very low levels of occurrence in November and December in the Central Pacific Sector and in July and August in the 0-75 deg West Sector Satellite in-situ data, scintillation and spread F observations will be reviewed. The limitation of each data set will be outlined particularly as relevant to the bias produced by the existence of thin versus extended layers of irregularities. A cartoon as to the occurrence pattern, as we see it, as a function of longitude will be shown.