Longitudinal variability of complexities associated with equatorial electrojet and its coupling with Solar Quiet Daily variation Sq field

IF 2.8 3区地球科学 Q2 ASTRONOMY & ASTROPHYSICS

Advances in Space Research Pub Date : 2024-08-03 DOI:10.1016/j.asr.2024.07.075

Babatunde Rabiu, Samuel Ogunjo, Oluwakemi Dare-Idowu, Ibiyinka Fuwape

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Abstract

The large-scale solar quiet (Sq) current and the Equatorial Electrojet (EEJ) current are two structures produced by electric current in the Earth’s ionosphere. For a long time, the characteristics of these two currents, particularly whether the EEJ is an extended portion of the Sq current has been a hot topic within the community. This study examined magnetic data obtained from ground-based magnetometers at 6 representative stations for the year 2009 and for geomagnetically quiet days (). The selected stations are along the magnetic equator in the South America (Huancayo), Africa (Ilorin; Addis Ababa), and the Philippines (Langkawi, dip latitude ; Davao, dip latitude ; Yap, dip latitude ). Results showed that both current systems are complex, and this complexity varies significantly from one longitudinal station to another. The strongest and weakest complexity were found in Huancayo and Ilorin, respectively. Afterwards, using four entropy quantifiers (Phase synchronization, Mutual Information, Ensemble Symbolic Coupling Traces, and S-independence), this study examined the relationship between the EEJ and Sq currents. Results revealed clearly a significant information exchange between both currents; that is, the Sq and EEJ currents are indeed coupled. As a step further, using the transfer entropy approach, a directional investigation was carried out to ascertain the direction of information flow between the Sq and EEJ stations. Observations revealed that due to the weak coupling obtained over the African sectors, only the currents over these stations exchanged information. This study further discussed the possible physical mechanisms responsible for the identified variabilities.

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赤道电射流相关复杂性的纵向变化及其与太阳静日变化 Sq 场的耦合关系

大尺度日静（Sq）流和赤道电射流（EEJ）是地球电离层中电流产生的两种结构。长期以来，这两种电流的特征，特别是 EEJ 是否是 Sq 电流的延伸部分一直是学术界的热门话题。本研究考察了 2009 年和地磁静止日（）6 个代表性站点的地基磁强计获得的磁数据。所选站点位于南美洲（万卡约）、非洲（伊洛林；亚的斯亚贝巴）和菲律宾（兰卡威，倾角纬度；达沃，倾角纬度；雅浦，倾角纬度）的磁赤道沿线。结果表明，这两种海流系统都很复杂，而且复杂程度在不同经度站之间有很大差异。万卡约和伊洛林的复杂性分别最强和最弱。随后，本研究利用四个熵量器（相位同步、互信息、组合符号耦合轨迹和 S-独立性），研究了 EEJ 与 Sq 海流之间的关系。结果清楚地表明，这两种电流之间存在重要的信息交流；也就是说，Sq 电流和 EEJ 电流确实是耦合的。为了进一步确定 Sq 站和 EEJ 站之间的信息流方向，我们利用传递熵方法进行了定向调查。观测结果表明，由于非洲扇区的耦合较弱，只有这些站点上的海流进行了信息交换。这项研究进一步讨论了造成已查明变异的可能物理机制。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Advances in Space Research 地学天文-地球科学综合

CiteScore

5.20

自引率

11.50%

发文量

800

审稿时长

5.8 months

期刊介绍： The COSPAR publication Advances in Space Research (ASR) is an open journal covering all areas of space research including: space studies of the Earth''s surface, meteorology, climate, the Earth-Moon system, planets and small bodies of the solar system, upper atmospheres, ionospheres and magnetospheres of the Earth and planets including reference atmospheres, space plasmas in the solar system, astrophysics from space, materials sciences in space, fundamental physics in space, space debris, space weather, Earth observations of space phenomena, etc. NB: Please note that manuscripts related to life sciences as related to space are no more accepted for submission to Advances in Space Research. Such manuscripts should now be submitted to the new COSPAR Journal Life Sciences in Space Research (LSSR). All submissions are reviewed by two scientists in the field. COSPAR is an interdisciplinary scientific organization concerned with the progress of space research on an international scale. Operating under the rules of ICSU, COSPAR ignores political considerations and considers all questions solely from the scientific viewpoint.