Ionospheric upwelling and the level of associated noise at solar minimum

IF 1.7 4区 地球科学 Q3 ASTRONOMY & ASTROPHYSICS
Timothy Wemimo David, Chizurumoke Michael Michael, Darren Wright, A. T. Talabi, A. Ajetunmobi
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引用次数: 0

Abstract

Abstract. We have studied the ionospheric upwelling with a magnitude of above 1013 m−2 s−1 using the data during the European Incoherent Scatter Scientific Association (EISCAT) Svalbard Radar International Polar Year (IPY-ESR) 2007 campaign, which coincides with the solar minimum. The noise level in low-, medium- and high-flux upflows is investigated. We found that the noise level in high-flux upflow is about 93 %, while in the low and medium categories it is 62 % and 80 %, respectively. This shows that robust and stringent filtering techniques must be ensured when analysing incoherent data in order not to introduce bias to the result. Analysis reveals that the frequency of the low-flux upflow events is about 8 and 73 times the medium- and high-flux upflow events, respectively. Seasonal observation shows that the noise level in the upflow classes is predominantly high during winter. The noise is minimal in summer, with a notable result indicating occurrence of actual data above noise in the low-flux class. Moreover, the percentage occurrence of the noise level in the data increases with increasing flux strength, irrespective of the season. Further analysis reveals that the noise level in the local time variation peaked around 17:00–18:00 LT (local time) and minimum around 12:00 LT.
电离层上涌和太阳极小期的相关噪声水平
摘要。我们利用欧洲非相干散射科学协会(EISCAT)斯瓦尔巴雷达国际极地年(IPY-ESR)2007 年活动期间的数据研究了幅度大于 1013 m-2 s-1 的电离层上涌,这次活动恰逢太阳最小值。对低、中、高流量上溢流的噪声水平进行了研究。我们发现,高流量上升气流中的噪声水平约为 93%,而低流量和中等流量上升气流中的噪声水平分别为 62% 和 80%。这表明,在分析不连贯数据时,必须确保采用稳健而严格的过滤技术,以免结果出现偏差。分析表明,低流量上升事件的频率分别约为中流量和高流量上升事件的 8 倍和 73 倍。季节性观测结果表明,上升气流等级的噪声水平主要在冬季较高。夏季的噪声很小,值得注意的是,低流量等级的实际数据高于噪声。此外,随着流量强度的增加,数据中出现噪声的百分比也在增加,与季节无关。进一步分析表明,当地时间变化中的噪声水平在当地时间 17:00-18:00 左右达到峰值,在当地时间 12:00 左右达到最小值。
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来源期刊
Annales Geophysicae
Annales Geophysicae 地学-地球科学综合
CiteScore
4.30
自引率
0.00%
发文量
42
审稿时长
2 months
期刊介绍: Annales Geophysicae (ANGEO) is a not-for-profit international multi- and inter-disciplinary scientific open-access journal in the field of solar–terrestrial and planetary sciences. ANGEO publishes original articles and short communications (letters) on research of the Sun–Earth system, including the science of space weather, solar–terrestrial plasma physics, the Earth''s ionosphere and atmosphere, the magnetosphere, and the study of planets and planetary systems, the interaction between the different spheres of a planet, and the interaction across the planetary system. Topics range from space weathering, planetary magnetic field, and planetary interior and surface dynamics to the formation and evolution of planetary systems.
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