Global characterization of the equatorial ionospheric anomaly with data from the global ultraviolet imager

The Equatorial Anomaly (EA) is host to the highest ionospheric densities in the Earth's atmosphere. Disturbances within the EA result in plasma density depletions and large density gradients. In this dissertation we present a method for measuring EA morphology using nighttime 135.6 nm radiance observed by the Global Ultraviolet Imager (GUVI) on-board the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) spacecraft. The method uses the singular value decomposition to estimate an along-track intensity profile as TIMED passes over the EA. The method is unique in that it removes intensity depletions due to equatorial plasma bubbles (EPBs) from the estimated intensity profile. Thus, the profiles reflect plasma distribution in response to equatorial E x B drifts and neutral winds.; A set of metrics including crest maximum intensity (CM) and crest latitude (CL) is extracted from the intensity profiles. EPBs are also detected. By using these metrics, extensive observations of EA and EPB morphology show that EA morphology can be well characterized by data taken from the 2030-2130 MLT range. Further, this dissertation identifies crest symmetry in intensity and latitude as an indicator of both EA and EPB morphology. For all longitudes, the crest-to-trough ratio (CTR) is shown to be well correlated with the EPB rate. While the CTR may drop with solar flux, EPB levels do not. Thus, the absolute CTR, is less an indicator than the change in the CTR, as a function of longitude for a given season and solar flux. One significant exception to this correlation is observed in the Pacific sector during the June solstice. In this case the EPB rate is high despite a low CTR.; In order to estimate global EA morphology for all night local times, the data, are used to train empirical models of the CMS and CLS. Our results indicate that EA enhancement is well correlated with F10.7 cm solar flux, especially during equinox. In terms of seasonal dependence we find that at equinox, north and south crest latitude symmetry occurs before 2300 MLT except in the African-Indian sector where CSL≥CNL . Before 2300 MIT during the June solstice, CNM≤CSM andCNL≥C SL while the reverse is true during the December solstice. We also study the driver-response relationship between the equatorial zonal electric field and the EA. This is done by comparing the vertical plasma drift velocity as predicted by the Scherliess and Fejer empirical model with our EA crest models. Comparing the maximum CM (MaxCM) and maximum CL (MaxCL) observed in a crest with the maximum vertical drift of the prereversal enhancement (MaxVD), we find that the equinox EA response time as a function of longitude is 2.5 to 5 hours in the north crest and 2 to 3.25 hours in the south crest. During the solstices minimum response times were observed at under 1 hour. The magnitude of MaxCM is coarsely correlated with MaxVD. During equinox MaxCL is well correlated with MaxVD.