Effects of Substorms on High‐Latitude Upper Thermospheric Winds
Effects of Substorms on High‐Latitude Upper Thermospheric Winds
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DOI：
10.1029/2020ja028193
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发表时间：
2020-12
期刊：
影响因子：
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通讯作者：
Y. Zou;L. Lyons;M. Conde;R. Varney;V. Angelopoulos;S. Mende
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文献类型：
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作者：
Y. Zou;L. Lyons;M. Conde;R. Varney;V. Angelopoulos;S. Mende
在磁层亚暴期间，高纬度电离层等离子体对流会发生显着变化。然而，热层上层风是如何变化的还没有得到很好的理解，并且报道了相互矛盾的结论。在这里，我们利用一系列扫描多普勒成像仪（SDI），THEMIS全天空成像仪（ASI）和扑克牌平板非相干散射雷达（PFISR）研究亚暴对高纬度上层热层风的影响。空间数据基础设施提供了对亚暴作出反应的二维空间风动力学镶嵌图，并作为时间的函数，而空间数据基础设施和电离层电离层辐射同步监测仪同时监测极光发射和电离层参数。在亚暴发展阶段，中性风的经典双单体全球环流加强。亚风暴爆发后，这些风的纬向分量在午夜扇形区被强烈抑制，而远离午夜扇形区的风的双胞环流则增强。发作前和发作后增强均高于安静时间值≥100 m/s，并且发作后增强发生在比发作前增强更宽的纬度和当地时间区域。在午夜和午夜后的部门的纬向风分量加速向南到亚极光纬度。我们的研究结果表明，亚暴通过改变风向和风速显着改变了上层热层风环流，因此对整个磁层-电离层-热层系统非常重要。
During magnetospheric substorms, high‐latitude ionospheric plasma convection is known to change dramatically. How upper thermospheric winds change, however, has not been well understood, and conflicting conclusions have been reported. Here, we study the effect of substorms on high‐latitude upper thermospheric winds by taking advantage of a chain of scanning Doppler imagers (SDIs), THEMIS all‐sky imagers (ASIs), and the Poker Flat incoherent scatter radar (PFISR). SDIs provide mosaics of wind dynamics in response to substorms in two dimensions in space and as a function of time, while ASIs and PFISR concurrently monitor auroral emissions and ionospheric parameters. During the substorm growth phase, the classical two‐cell global circulation of neutral winds intensifies. After substorm onset, the zonal component of these winds is strongly suppressed in the midnight sector, whereas away from the midnight sector two‐cell circulation of winds is enhanced. Both pre and postonset enhancements are ≥100 m/s above the quiet‐time value, and postonset enhancement occurs over a broader latitude and local‐time area than preonset enhancement. The meridional wind component in the midnight and postmidnight sectors is accelerated southward to subauroral latitudes. Our findings suggest that substorms significantly modify the upper‐thermospheric wind circulation by changing the wind direction and speed and therefore are important for the entire magnetosphere‐ionosphere‐thermosphere system.