A Study of Observations of Ionospheric Upwelling Made by the EISCAT Svalbard Radar During the International Polar Year Campaign of 2007
A Study of Observations of Ionospheric Upwelling Made by the EISCAT Svalbard Radar During the International Polar Year Campaign of 2007
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DOI：
10.1002/2017ja024802
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发表时间：
2018-03
期刊：
影响因子：
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通讯作者：
T. W. David;D. Wright;S. Milan;S. Cowley;J. Davies;I. McCrea
中科院分区：
文献类型：
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作者：
T. W. David;D. Wright;S. Milan;S. Cowley;J. Davies;I. McCrea
我们利用2007国际极年活动期间获得的EISCAT斯瓦尔巴特群岛雷达数据，研究通量超过1013 m−2 s−1的电离层上升流事件。在这项研究中，我们已经将上升流事件分为低，中，高通量上升流，我们报告这些不同类别的发病率和季节分布。据观察，高上升流通量是比较罕见的，低通量上升流事件是一种常见的现象。分析表明，在地磁扰动期间，低、中和高通量上升流在当地中午附近的出现率分别为31%、16%和2%。与先前关于垂直和场向流的研究一致，观察到离子上升流在广泛的地磁条件下发生，下降流通量发生率低于上升流发生率。然而，与以前的观测结果相反，在高度扰动的地磁条件下，中午前后的上升流发生率高于中等地磁条件。对季节分布的分析表明，虽然高通量上升流在夏季当地中午左右达到峰值，其发生主要是由高地磁扰动驱动的，但低通量上升流的发生广泛分布在所有季节，地磁活动条件和一天中的时间。中通量上升流事件虽然分布在所有季节，但显示出与高Kp密切相关的发生峰值。此外，在高度扰动条件下，低通量和中等通量上升流事件在冬季出现最少，而高通量上升流事件的最少发生在秋季。
We have used EISCAT Svalbard Radar data, obtained during the International Polar Year 2007 campaign, to study ionospheric upflow events with fluxes exceeding 1013 m−2 s−1. In this study, we have classified the upflow events into low, medium, and high flux upflows, and we report on the incidence and seasonal distribution of these different classes. It is observed that high upflow fluxes are comparatively rare and low flux upflow events are a frequent phenomenon. Analysis shows that occurrence peaks around local noon at 31%, 16%, and 2% for low, medium, and high‐flux upflow, respectively, during geomagnetically disturbed periods. In agreement with previous studies on vertical and field‐aligned flows, ion upflow is observed to take place over a wide range of geomagnetic conditions, with downflow flux occurrence being lower than upflow occurrence. In contrast to previous observations, however, the upflow occurrence is greater around noon during highly disturbed geomagnetic conditions than for moderate geomagnetic conditions. Analysis of the seasonal distribution reveals that, while high‐flux upflow has its peak around local noon in the summer, with its occurrence being driven predominantly by high geomagnetic disturbance, the occurrence of low‐flux upflow is broadly distributed across all seasons, geomagnetic activity conditions, and times of day. The medium‐flux upflow events, although distributed across all seasons, show an occurrence peak strongly related to high Kp. Furthermore, during highly disturbed conditions, the low‐flux and medium‐flux upflow events show a minimum occurrence during the winter, whereas minimum occurrence for the high‐flux upflow events occurs in autumn.