极区中间层-低热层大气风场和成分对地磁活动响应的研究

The mesosphere and low thermosphere (MLT) region is an interesting region where the neutral atmosphere changes to the ionization atmosphere. The MLT region is influenced by geomagnetic effects produced by solar activity through the interaction between the solar wind and Earth's magnetosphere-ionosphere-thermosphere (MIT) system. Many studies have reported that geomagnetic activity can significantly affect global MLT composition through energetic particle precipitation into the MLT region. This leads to a large increase in odd nitrogen and odd hydrogen, and a strong depletion of ozone in the global MLT region. In this study, the horizontal wind observed by northern and southern polar meteor radars and medium radars were utilized to examine geomagnetic influence in MLT region. By analyzing satellite observation in MLT region, we also examine the increase of odd nitrogen and the depletion of ozone caused by energetic particle precipitation during geomagnetic disturbance. At last, we also examine the modulation of the polar mesospheric summer echo (PMSE) observed by the Davis Mesosphere-Stratosphere-Troposphere (MST) radar during geomagnetic forcing and attempt to investigate influence of the energetic particle precipitation on the dust plasma in MLT region.

中间层-低热层（Mesosphere and Low Thermosphere, MLT）是地球中性大气到电离大气的过渡区域。太阳活动产生的能量可以通过地球磁层-热层-电离层系统传递到中间层-低热层大气中，引起有趣的日地耦合现象。研究表明，中间层-低热层的大气密度和化学成分对地磁活动存在明显的响应。但是，地磁活动是否可以影响中间层-低热层中性大气风场仍不是很清楚。本项目将分别利用南北极流星雷达和中频雷达观测资料来研究中间层-低热层中性大气风场对地磁活动的响应。同时，利用全球卫星观测资料来研究中间层-低热层大气化学成分如氮氧化物和臭氧等对地磁活动引起的高能粒子沉降的响应，并且讨论中性大气和大气化学物质成分在地磁活动期间变化的联系。最后，利用南极中间层-平流层-对流层（MST）雷达观测的极区中间层夏季回波数据，进一步研究地磁活动对极区中间层-低热层大气中的尘埃等离子体的影响

中间层-低热层（Mesosphere and Low Thermosphere, MLT）是中性大气到电离大气的过渡区域。太阳活动产生的能量可以通过地球磁层-热层-电离层系统传递到中间层-低热层大气中，引起有趣的日地耦合现象。本项目利用了南北极地基雷达中间层-低热层大气风场观测资料来研究强磁暴和重现性地磁活动对中间层-低热层大气风场影响，首次发现了地磁活动显著影响极区大气风场和大气潮汐的观测证据。同时利用卫星观测资料研究了地磁活动期间高能粒子沉降对中间层-低热层大气化学成分（HOx和O3）影响，并探讨化学成分的变化对背景中性大气的影响。最后，研究地磁活动期间中间层-低热层大气温度以及中间层顶出现高度变化过程，系统探讨了地磁活动期间高能粒子沉降对中间层-低热层大气的影响。