Climatology of Equatorial Ionization Anomaly (EIA): GOLD Observations and Coupled GITM-SAMI3 Simulations

Equatorial ionization anomaly (EIA) is a prominent phenomenon in the low and mid-latitude ionosphere and is characterized by the two arcs of intense plasma density on either side of the magnetic equator. Since its launch, the Global-scale Observations of the Limb and Disk (GOLD) has continuously observed the Earth's nighttime ionosphere from 20:10 UT to 00:15 UT the following day on a daily basis and has provided unprecedented information about the nighttime EIA. In this work, we have analyzed the six years (2019-2024) of OI 135.6 nm radiance data from the GOLD mission to investigate the influence of solar activity and seasons on the EIA crests' peak amplitude, peak location, and latitudinal extension (width) at different longitudes spanning from America to Africa during the quiet conditions (Kp<3). For the first time, we report a comprehensive study of asymmetry in the EIA crests' width, which differs significantly in different longitudes. To understand the mechanisms driving the longitudinal differences in EIA, we have employed the coupled GITM-SAMI3 model.