{"title":"2021 年 5 月东亚地区地磁静止期日落后电离层电子密度增强的纬度特征","authors":"Honglian Hao, Biqiang Zhao, Xinan Yue, Feng Ding, Guozhu Li, Wenjie Sun, Zhipeng Ren, Libo Liu","doi":"10.1029/2024JA033047","DOIUrl":null,"url":null,"abstract":"<div>\n \n \n <section>\n \n <p>This study investigated the latitudinal variations of post-sunset enhancements in the ionospheric electron density during the geomagnetic quiet period in May 2021 with a combination of high-precision ionospheric parameters obtained from four ionosondes, Beidou geostationary satellite (BD-GEO) receiver network and Sanya incoherent scatter radar (SYISR). We identified four categories of post-sunset enhancement phenomena (Types 1–4), each with unique spatial and temporal evolutions, yet uniformly accompanied by a decrease in hmF2. Measurements of plasma drift vector velocities from SYISR and hmF2 gradients across various latitudes provided pivotal insights, confirming that the ionospheric post-sunset enhancements can result from downward plasma motion due to westward electric field, downward field-aligned drift, or a combination of both. For Type 1, dominated by field-aligned drift, plasma density enhancements not only intensify at low latitudes but may also extend to mid-latitudes, exhibiting a distinct temporal delay with increasing latitude. In contrast, Type 4, primarily driven by the westward electric field, is characterized by modest increases in plasma density confined to localized low-latitude regions, with no observable latitudinal time delay in the peak of enhancements. Types 2 and 3, which are subject to the combined influence of the westward electric field and field-aligned drift, exhibit plasma density increases at certain low-latitude areas, with Type 2 presenting a delayed pattern and Type 3 showing none with rising latitude. Meanwhile, neutral winds can partially account for the observed post-sunset enhancement from low to middle latitudes. These findings offer new insights into the factors influencing ionospheric behavior after sunset.</p>\n </section>\n </div>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Latitudinal Characteristics of the Post-Sunset Enhancements in Ionospheric Electron Density During the Geomagnetic Quiet Period in May 2021 Over East-Asian Region\",\"authors\":\"Honglian Hao, Biqiang Zhao, Xinan Yue, Feng Ding, Guozhu Li, Wenjie Sun, Zhipeng Ren, Libo Liu\",\"doi\":\"10.1029/2024JA033047\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div>\\n \\n \\n <section>\\n \\n <p>This study investigated the latitudinal variations of post-sunset enhancements in the ionospheric electron density during the geomagnetic quiet period in May 2021 with a combination of high-precision ionospheric parameters obtained from four ionosondes, Beidou geostationary satellite (BD-GEO) receiver network and Sanya incoherent scatter radar (SYISR). We identified four categories of post-sunset enhancement phenomena (Types 1–4), each with unique spatial and temporal evolutions, yet uniformly accompanied by a decrease in hmF2. Measurements of plasma drift vector velocities from SYISR and hmF2 gradients across various latitudes provided pivotal insights, confirming that the ionospheric post-sunset enhancements can result from downward plasma motion due to westward electric field, downward field-aligned drift, or a combination of both. For Type 1, dominated by field-aligned drift, plasma density enhancements not only intensify at low latitudes but may also extend to mid-latitudes, exhibiting a distinct temporal delay with increasing latitude. In contrast, Type 4, primarily driven by the westward electric field, is characterized by modest increases in plasma density confined to localized low-latitude regions, with no observable latitudinal time delay in the peak of enhancements. Types 2 and 3, which are subject to the combined influence of the westward electric field and field-aligned drift, exhibit plasma density increases at certain low-latitude areas, with Type 2 presenting a delayed pattern and Type 3 showing none with rising latitude. Meanwhile, neutral winds can partially account for the observed post-sunset enhancement from low to middle latitudes. These findings offer new insights into the factors influencing ionospheric behavior after sunset.</p>\\n </section>\\n </div>\",\"PeriodicalId\":15894,\"journal\":{\"name\":\"Journal of Geophysical Research: Space Physics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.6000,\"publicationDate\":\"2024-10-19\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Geophysical Research: Space Physics\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1029/2024JA033047\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Geophysical Research: Space Physics","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1029/2024JA033047","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
Latitudinal Characteristics of the Post-Sunset Enhancements in Ionospheric Electron Density During the Geomagnetic Quiet Period in May 2021 Over East-Asian Region
This study investigated the latitudinal variations of post-sunset enhancements in the ionospheric electron density during the geomagnetic quiet period in May 2021 with a combination of high-precision ionospheric parameters obtained from four ionosondes, Beidou geostationary satellite (BD-GEO) receiver network and Sanya incoherent scatter radar (SYISR). We identified four categories of post-sunset enhancement phenomena (Types 1–4), each with unique spatial and temporal evolutions, yet uniformly accompanied by a decrease in hmF2. Measurements of plasma drift vector velocities from SYISR and hmF2 gradients across various latitudes provided pivotal insights, confirming that the ionospheric post-sunset enhancements can result from downward plasma motion due to westward electric field, downward field-aligned drift, or a combination of both. For Type 1, dominated by field-aligned drift, plasma density enhancements not only intensify at low latitudes but may also extend to mid-latitudes, exhibiting a distinct temporal delay with increasing latitude. In contrast, Type 4, primarily driven by the westward electric field, is characterized by modest increases in plasma density confined to localized low-latitude regions, with no observable latitudinal time delay in the peak of enhancements. Types 2 and 3, which are subject to the combined influence of the westward electric field and field-aligned drift, exhibit plasma density increases at certain low-latitude areas, with Type 2 presenting a delayed pattern and Type 3 showing none with rising latitude. Meanwhile, neutral winds can partially account for the observed post-sunset enhancement from low to middle latitudes. These findings offer new insights into the factors influencing ionospheric behavior after sunset.