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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >Zonal currents in the F region deduced from Swarm constellation measurements
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Zonal currents in the F region deduced from Swarm constellation measurements

机译：F地区纬向气流推导出群星座的测量

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摘要

The Swarm constellation has been used to estimate zonal currents in the topside F region ionosphere at about 500 km. Near-simultaneous magnetic field measurements from two altitudes but the same meridian are used for the current density calculations. We consider the period 15 February to 23 June 2014 for deriving a full 24 h local time coverage of the latitudinal distribution over ±50° in magnetic latitude. Intervals with close orbital phasing at the two heights are considered, which repeat every 6 days. From such days seven successive orbits are used where the epochs of equator crossings differ by less than 2 min. Deduced current densities are predominantly eastward (about 20 nA/m~2) on the dayside and westward (about 10 nA/m~2) on the nightside. A number of different drivers contribute to the observed total current. We identified the gravity-driven eastward current as the most prominent at low latitudes. Eastward currents in the Northern Hemisphere are clearly stronger than in the south. This is attributed to the proximity of our study period to June solstice, when the solar radiation is stronger in the north. In addition, interhemispheric winds from the Northern (summer) to the Southern (winter) Hemisphere contribute. They cause eastward currents in the north and westward in the south. We find a relatively large variability of the zonal currents both in space and time. The standard deviation is at least twice as large as the mean value of current density. This large variability is suggested to be related to gravity wave forcing from below.
机译：蜂群星座被用来估计纬向气流上部F地区电离层在约500公里。测量两个海拔不过是一样的子午线是用于电流密度计算。2014年6月23日为当地派生一个完整的24小时时间覆盖的纬向分布在磁纬度在±50°。两个高度接近轨道定相认为,重复每6天。连续七天的轨道的地方使用时代的赤道口岸相差小于2分钟。推导出电流密度主要是东(约20 nA / m ~ 2)的光面和西(大约10 nA / m ~ 2)在阴面。许多不同的司机做出贡献观察到的总电流。当前最gravity-driven向东突出在低纬度地区。北半球显然比在南方。我们的研究期间夏至,当太阳辐射在北方更强。另外,两半球间的风的北部(夏天)南部(冬季)半球贡献。在南方电流在北部和西部。我们找到一个相对大的可变性纬向电流在空间和时间。标准差是至少两倍电流密度的平均值。变异性是建议与重力有关波迫使从下面。

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