Responses of the middle and upper atmospheric wind to geomagnetic activities
本文利用漠河站、北京站、武汉站流星雷达观测到的中间层—低热层大气风场数据，分析研究了在2012-2018年地磁活动期间80-100公里高度大气的纬向风与经向风对地磁活动的响应特征。统计研究2012-2018年的风场数据，比较了在地磁平静期（Kp ≤ 2）和地磁扰动期（Kp ≥ 4）的日平均纬向风与经向风数据，得到在地磁活动期风场的变化特征，研究结果表明在地磁扰动时风场变化具有季节差异，并且在不同的纬度表现不同。对于纬向风，地磁活动在较高纬度地区更倾向于表现为中间层西风增强，低热层东风增强，其对纬向风的影响大约在3 m/s的量级，而对于纬度较低地区，在80-100 公里大气区域倾向于表现为东风增强，影响约在5 m/s量级左右。在春季地磁活动对纬向风的影响没有纬度差异，在夏/冬季随着纬度的降低中间层东风增强明显。地磁活动对经向风的影响具有季节差异，对春冬季节的影响强于夏秋季节，在冬季，对中低纬地区经向风的影响强于高纬地区。从计算结果来看对纬向风影响约在5 m/s到10 m/s量级，对经向风的影响大约在3 m/s到5 m/s的量级。地磁活动对中性大气风场的影响可以达到80公里，在这一高度，地磁活动对纬向风的影响在春季最强，达到8 m/s，对经向风的影响在春冬季节最强，达到5 m/s。Abstract:
Responses of the middle and upper atmospheric (80-100 km ) wind to geomagnetic activities have been investigated using neutral wind data from 2012 to 2018 years, which were observed by Mohe, Beijing and Wuhan Meteor radars. Daily averaged wind data for geomagnetic quiet condition (Kp ≤ 2) and geomagnetic disturb condition (Kp ≥ 4) were chosen for comparison, and the variation characteristics of wind during geomagnetic disturbances were obtained. The observations show that the influence of geomagnetic activity on zonal wind varied with seasons and latitudes. For zonal wind, the effect of geomagnetic activity at higher latitudes tended to be more westerly wind in the upper mesosphere and more easterly wind in the lower thermosphere, and the differences between disturbed and quiet conditions were on the order of 3 m/s; while for the lower latitudes, it tended to be more easterly wind in the 80-100 km region, and the influence were about 5 m/s. In spring, the three stations had similar tendencies, and had no latitude differences. But the easterly wind in the middle atmosphere became stronger with the decrease of latitude in summer/winter. The effect of geomagnetic activities on the meridional wind had seasonal differences. The influence of geomagnetic activities in spring and winter was stronger than that in summer and autumn. In winter, the effect of geomagnetic activity on the meridional wind in middle and low latitudes was stronger than that in higher latitudes. According to the calculation results, the influence on zonal wind was about 5 m/s to 10 m/s, and on meridional wind was about 3 m/s to 5 m/s. The impact of geomagnetic activities on MLT wind can penetrate down to about 80 km. At this height, the influence on zonal wind was the strongest in spring, reaching 8 m/s, and on meridional wind was the strongest in spring/winter, reaching 5 m/s.
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