foF2 Seasonal Asymmetry Diurnal Variation Study during Very Quiet Geomagnetic Activity at Dakar Station

IF 1 Q3 GEOCHEMISTRY & GEOPHYSICS
Sibri Alphonse Sandwidi, D. A. Gnabahou, F. Ouattara
{"title":"foF2 Seasonal Asymmetry Diurnal Variation Study during Very Quiet Geomagnetic Activity at Dakar Station","authors":"Sibri Alphonse Sandwidi, D. A. Gnabahou, F. Ouattara","doi":"10.1155/2020/8896188","DOIUrl":null,"url":null,"abstract":"This paper aims to study the foF2 seasonal asymmetry diurnal variation at Dakar station from 1976 to 1995. We show that equinoctial asymmetry is less pronounced and somewhere is absent throughout 21 and 22 solar cycles. The absence of equinoctial asymmetry may be due to Russell-McPherron mechanism and the vertical drift . The solstice anomaly or annual anomaly is always observed throughout both 21 and 22 solar cycles as measured at Dakar ionosonde. The maximum negative value of σfoF2, fairly equal to -65%, is observed during the decreasing phase at solstice time; this value appeared usually at 0200 LT except during the maximum phase during which it is observed at 2300 LT. The maximum positive value, fairly equal to +94%, is observed at 0600 LT during solar minimum at solstice time. This annual asymmetry may be due to neutral composition asymmetric variation and solar radiation annual asymmetry with the solstice time. The semiannual asymmetry is also observed during all solar cycle phases. The maximum positive value (+73%) is observed at 2300 LT during solar maximum, and its maximum negative (-12%) is observed during the increasing phase. We established, as the case of annual asymmetry, that this asymmetry could not be explained by the asymmetry in vertical velocity phenomenon but by the axial mechanism, the “thermospheric spoon” mechanism, and the seasonally varying eddy mixing phenomenon.","PeriodicalId":45602,"journal":{"name":"International Journal of Geophysics","volume":" ","pages":"1-10"},"PeriodicalIF":1.0000,"publicationDate":"2020-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2020/8896188","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Geophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1155/2020/8896188","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOCHEMISTRY & GEOPHYSICS","Score":null,"Total":0}
引用次数: 2

Abstract

This paper aims to study the foF2 seasonal asymmetry diurnal variation at Dakar station from 1976 to 1995. We show that equinoctial asymmetry is less pronounced and somewhere is absent throughout 21 and 22 solar cycles. The absence of equinoctial asymmetry may be due to Russell-McPherron mechanism and the vertical drift . The solstice anomaly or annual anomaly is always observed throughout both 21 and 22 solar cycles as measured at Dakar ionosonde. The maximum negative value of σfoF2, fairly equal to -65%, is observed during the decreasing phase at solstice time; this value appeared usually at 0200 LT except during the maximum phase during which it is observed at 2300 LT. The maximum positive value, fairly equal to +94%, is observed at 0600 LT during solar minimum at solstice time. This annual asymmetry may be due to neutral composition asymmetric variation and solar radiation annual asymmetry with the solstice time. The semiannual asymmetry is also observed during all solar cycle phases. The maximum positive value (+73%) is observed at 2300 LT during solar maximum, and its maximum negative (-12%) is observed during the increasing phase. We established, as the case of annual asymmetry, that this asymmetry could not be explained by the asymmetry in vertical velocity phenomenon but by the axial mechanism, the “thermospheric spoon” mechanism, and the seasonally varying eddy mixing phenomenon.
达喀尔站极静地磁活动期间foF2季节不对称日变化研究
本文旨在研究1976 ~ 1995年达喀尔站foF2季节不对称日变化。我们发现,在21和22个太阳周期中,春分不对称不太明显,有些地方不存在。分点不对称的存在可能与罗素-麦克菲龙机制和垂直漂移有关。在达喀尔电离层探空仪测量的21和22个太阳周期中,总能观测到至日异常或年异常。σfoF2的最大值为-65%,出现在至日递减阶段;这个值通常出现在0200lt,除了在2300 LT观测到的最大阶段。最大正值,相当等于+94%,是在0600lt观测到的,太阳最小值在至时。这种年不对称可能是由于中性成分的不对称变化和太阳辐射的年不对称与冬至时间有关。半年一次的不对称性在所有太阳周期阶段也被观察到。最大正值(+73%)出现在2300 LT的太阳活动极大期,最大负值(-12%)出现在增加阶段。以年不对称为例,我们确定了这种不对称不能用垂直速度现象的不对称来解释,而可以用轴向机制、“热层勺子”机制和季节变化的涡旋混合现象来解释。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
求助全文
约1分钟内获得全文 求助全文
来源期刊
International Journal of Geophysics
International Journal of Geophysics GEOCHEMISTRY & GEOPHYSICS-
CiteScore
1.50
自引率
0.00%
发文量
12
审稿时长
21 weeks
期刊介绍: International Journal of Geophysics is a peer-reviewed, Open Access journal that publishes original research articles as well as review articles in all areas of theoretical, observational, applied, and computational geophysics.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
确定
请完成安全验证×
copy
已复制链接
快去分享给好友吧!
我知道了
右上角分享
点击右上角分享
0
联系我们:info@booksci.cn Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。 Copyright © 2023 布克学术 All rights reserved.
京ICP备2023020795号-1
ghs 京公网安备 11010802042870号
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术官方微信