Observation of equatorial nighttime medium‐scale traveling ionospheric disturbances in 630‐nm airglow images over 7 years
Observation of equatorial nighttime medium‐scale traveling ionospheric disturbances in 630‐nm airglow images over 7 years
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DOI：
10.1029/2012ja017758
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发表时间：
2012-10
影响因子：
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通讯作者：
D. Fukushima;K. Shiokawa;Y. Otsuka;T. Ogawa
中科院分区：
文献类型：
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作者：
D. Fukushima;K. Shiokawa;Y. Otsuka;T. Ogawa
[1] 我们报告了 2002 年 10 月至 2009 年 10 月 7 年间在印度尼西亚 Kototabang（地理经度：100.3°E；地理纬度：0.2°S；地磁纬度：10.6°S）观测到的夜间中尺度移动电离层扰动（MSTID）。MSTID 是通过使用高度Kototabang 的灵敏全天空气辉成像仪。 7年观测到的MSTID水平相速度、周期和水平波长的平均值和标准差分别为320±170 m/s、42±11 min和790±440 km。观测到的 MSTID 的发生率随着太阳活动的减弱而降低。 MSTID 的平均水平波长随着太阳活动的减少而增加。在 7 年的观测中，南向 MSTID 占主导地位。这些事实与观测到的 MSTID 是由热层中的重力波引起的假设相一致。此外，我们将观测到的 MSTID 的传播方向与对流层对流活动的位置进行了比较，这些事件中产生观测到的 MSTID 的重力波可能存在于低层大气中。在 81% 的 MSTID 事件中，在距 MSTID 源方向 ±30 度范围内发现了强对流层对流。在这种事件中，重力波可能是由对流层的深层对流产生的，并直接传播到热层中。
[1] We report on nighttime medium-scale traveling ionospheric disturbances (MSTIDs) observed at Kototabang, Indonesia (geographic longitude: 100.3°E; geographic latitude: 0.2°S; and geomagnetic latitude: 10.6°S) during a 7-year period from October 2002 to October 2009. MSTIDs were observed in 630-nm nighttime airglow images by using a highly sensitive all-sky airglow imager at Kototabang. The averages and standard deviations of horizontal phase velocity, period, and horizontal wavelength of MSTIDs observed during the 7 years were 320 ± 170 m/s, 42 ± 11 min, and 790 ± 440 km, respectively. The occurrence rate of the observed MSTIDs decreased with decreasing solar activity. The average horizontal wavelength of MSTIDs increased with decreasing solar activity. Southward MSTIDs were dominant throughout the 7 years of observations. These facts are consistent with the hypothesis that the observed MSTIDs are caused by gravity waves in the thermosphere. Moreover, we compared the propagation directions of the observed MSTIDs with the locations of tropospheric convection activity for the events where gravity waves producing the observed MSTIDs could have existed in the lower atmosphere. Strong tropospheric convection was found within ±30 degrees from the source directions of MSTIDs in 81% of the MSTID events. In such events, gravity waves were possibly generated from deep convection in the troposphere and directly propagated into the thermosphere.