During geomagnetically quiet and solar minimum conditions, spatial variations of the early morning thermosphere‐ionosphere (TI) system are expected to be mainly governed by wave dynamics. To study the postmidnight dynamical coupling, we investigated the early morning equatorial ionization anomaly (EIA) using Global‐scale Observations of the Limb and Disk (GOLD) measurements of OI‐135.6 nm nightglow emission and global navigation satellite system (GNSS)‐based total electron content (TEC) maps. The EIA structures in the OI‐135.6 nm emission over the American landmass resemble, spatially and temporally, those observed in the GNSS‐TEC maps. The early morning EIA (EM‐EIA) crests are well separated in latitude and mostly located over the middle of South America during October–November. In February–April the crests are less separated in latitude and predominantly located over the west coast sector of South America. Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension (WACCMX) simulations with constant solar minimum and quiet‐geomagnetic conditions show that EM‐EIA can occur globally and shows properties similar to longitudinal Wave 4 pattern. Thus, we propose that EM‐EIA is driven by dynamical changes associated with the lower atmospheric waves.

中文翻译：

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从金观测到的清晨赤道电离异常

在地磁平静和太阳极少的条件下，预计清晨热层-电离层（TI）系统的空间变化将主要由波浪动力学控制。为了研究午夜后的动力耦合，我们使用全球规模的OI-135.6 nm夜辉发射和全球导航卫星系统（GNSS）的肢体和磁盘观测（GOLD）测量，调查了清晨的赤道电离异常（EIA）。电子含量（TEC）图。美国大陆上OI-135.6 nm发射中的EIA结构在空间和时间上类似于GNSS-TEC地图中观察到的结构。EIA（EM-EIA）清晨的波峰在纬度上分隔得很好，并且在10月至11月期间位于南美中部。在二月至四月，波峰在纬度上的间隔较小，并且主要位于南美的西海岸地区。具有恒定太阳最低和安静地磁条件的热球和电离层扩展（WACCMX）模拟的整个大气群落气候模型表明，EM-EIA可以全球发生，并且表现出类似于纵向波4模式的特性。因此，我们建议EM-EIA是由与较低大气波有关的动力学变化驱动的。