Modeling the behavior of ionosphere above Millstone Hill during the September 21-27, 1998 storm
Modeling the behavior of ionosphere above Millstone Hill during the September 21-27, 1998 storm
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DOI：
10.1016/j.jastp.2004.04.004
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发表时间：
2004-08
影响因子：
1.9
通讯作者：
J. Lei;Libo Liu;W. Wan;Shunrong Zhang
中科院分区：
文献类型：
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作者：
J. Lei;Libo Liu;W. Wan;Shunrong Zhang
采用理论电离层模型来研究 1998 年 9 月 21 日至 27 日风暴期间磨石山非相干散射雷达 (ISR) 观测到的电离层行为。 9月25日观察到的NmF2呈现显着的负相位，并且还观察到G条件（hmF2<200 km ）。基于标准输入参数（气候模型值）的模型结果与安静条件下观测到的电子密度吻合较好，但在扰动时期则存在较大差异。外层温度 Tex、中性风、原子氧密度 [O] 和分子氮密度 [N2] 以及太阳通量是根据 ISR 离子温度剖面和电子密度剖面推断的。我们的计算结果表明，9 月 25 日受干扰日的最高 Texis 高于 1700 K，[O] 平均减少了 2.2 倍，300 公里处的 [N2] 增加了约 1.8 倍。因此，[N2]/[O]比值的巨大变化很好地解释了此次风暴期间磨石山的负相位。此外，在受干扰的夜间，观测结果显示 NmF2 强烈减少，同时风暴突然开始 (SSC) 后 hmF2 显着增加。基于推断的Tex进行模拟，发现日落至午夜后F2层的抬升主要与赤道大风有关，子夜后hmF2的第二次上升是由于重组增加导致F2层底面Nein耗尽所致，而hmF2的“午夜塌陷”则归因于大规模的移动大气扰动。
A theoretical ionospheric model is employed to investigate the ionospheric behavior as observed by the incoherent-scatter radar (ISR) at Millstone Hill during the September 21–27, 1998 storm. The observed NmF2presented a significant negative phase on September 25, and a G condition (hmF2<200 km ) was also observed. The model results based on the standard input parameters (climatological model values) are in good agreement with the observed electron densities under quiet conditions, but there are large discrepancies during disturbed periods. The exospheric temperature Tex, neutral winds, atomic oxygen density [O] and molecular nitrogen density [N2], and solar flux are inferred from the ISR ion temperature profiles and from the electron density profiles. Our calculated results show that the maximum Texis higher than 1700 K , and an averaged decrease in [O] is a factor of 2.2 and an increase in [N2] at 300 km is about 1.8 times for the disturbed day, September 25, relative to the quiet day level. Therefore, the large change of [N2]/[O] ratio gives a good explanation for the negative phase at Millstone Hill during this storm. Furthermore, at the disturbed nighttime the observations show a strong NmF2decrease, accompanied by a significant hmF2increase after the sudden storm commencement (SSC). Simulations are carried out based on the inferred Tex. It is found that the uplift of F2layer during the period from sunset to post-midnight is mainly associated with the large equatorward winds, and a second rise in hmF2after midnight results from the depleted Nein the bottom-side of F2layer due to the increased recombination, while the “midnight collapse” of hmF2is attributed to the large-scale traveling atmospheric disturbances.