It has been noticed recently that the equatorial ionization anomaly (EIA) in the Brazilian eastern, middle, and western sectors present significant longitudinal variability within a short separation due to the presence of typical magnetic field structure over South America. Therefore, the main motivation of this study is to investigate day‐to‐day and month‐to‐month characteristics of the EIA in three closely spaced longitudinal sectors over the Brazilian region during the year 2016 in the descending phase of the solar activity. These three longitudinal sectors are perpendicular to the magnetic equator at its largest declination over the globe. The EIA showed a semiannual variation in all sectors with a major maximum during the summer, a minimum during the winter, and secondary maximum during spring. In addition, the EIA shows its classical behavior with a trough around the magnetic equator and crests at low latitudes (from ±15° to ±20°). When the EIA is not developed, the maximum ionization is located around the dip equatorial latitudes and the anomaly crest is absent. The number of days within 1 year that showed clear EIA development in the west, middle, and east sectors is 248 (78.2%), 236 (74.4%), and 265 (83.6%), respectively. The undeveloped/absence of EIA is also found often during the months of winter, and the numbers of such days during 2016 in the west, middle, and east are 69 (21.8%), 81 (25.6%), and 52 (16.4%), respectively. Also, the shape, strength, extent, and lifetimes of EIA crest have shown significant variabilities between the three sectors during different seasons. Further, a comparative analysis is carried out on the variations of EIA crest and lifetime between GPS observations and IRI‐2016 model, and the results are discussed.

中文翻译：

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太阳周期下降阶段巴西地区赤道电离异常（EIA）的每日和每月变化24

最近已经注意到，由于南美各地典型的磁场结构的存在，巴西东部，中部和西部地区的赤道电离异常（EIA）在短距离内呈现出明显的纵向变化。因此，这项研究的主要动机是研究在太阳活动下降阶段于2016年在巴西区域三个紧密间隔的纵向区域中EIA的每日和每月的特征。这三个纵向扇形垂直于磁赤道，磁赤道在全球范围内最大。EIA显示所有部门的半年度变化，夏季最大，冬季最小，春季最大。此外，EIA表现出其经典的行为，即围绕磁赤道的低谷和低纬度（从±15°到±20°）的波峰。当EIA未发展时，最大电离位于赤道赤道纬度附近，并且不存在异常波峰。一年之内，西部，中部和东部地区的环境影响评估显示明显发展的天数分别为248（78.2％），236（74.4％）和265（83.6％）。在冬季的几个月中也经常发现EIA不发达/缺乏EIA，2016年西部，中部和东部的此类日子分别为69（21.8％），81（25.6％）和52（16.4％） ）， 分别。此外，EIA波峰的形状，强度，范围和寿命在不同季节还显示出三个扇区之间的显着差异。进一步，