The Double Peak Superposition on the Equatorial Ionization Anomaly Crests During the 23 April 2023 Storm
Yanyan Yang, Chao Xiong, Shun‐Rong Zhang, Rui Yan, He Huang, Zeren Zhima, Weixing Pu, Song Xu, Jianping Huang, Hengxin Lu, Xu Yue, Xuhui Shen
Abstract
Abstract The typical equatorial ionization anomaly (EIA) exhibits two crests around the magnetic equator. Here we reported evidence for a double‐peak superposition at the EIA crest of each hemisphere, forming a four‐peak structure, with the additional peaks located ∼10° poleward of normal crests, as observed by CSES at 500 km altitudes on dayside, during the 23 April 2023 geomagnetic storm. Such a unique structure occurred when the eastward prompt penetration electric field (PPEF) was developed. Interestingly, distinctive large‐scale traveling ionospheric disturbances derived from GNSS‐TEC data propagated equatorward but not coincidently interacted with the EIA poleward peaks. The short‐duration intense PPEF may be the most plausible mechanism, which could cause the “fountain” plasma highly elevated into the topside which gradually fell into CSES altitudes on poleward sides of regular EIA crests, causing the superposition of crest in addition to nominal crest generated by the regular wind dynamo.