2005年8月24日强磁暴事件对高层大气密度的扰动

对2005年8月24日发生的突发型强磁暴(Kp峰值达到9)事件,利用星载大气密度探测器在轨实时的连续探测数据进行了处理和分析.结果表明,此次强磁暴事件期间,引起560 km高度附近大气密度剧烈扰动,并存在着两种响应过程.一种是跟随地磁扰动程度变化的全球性大气密度涨落变化,响应时间滞后6h左右,最大涨落变化比为2.5;另一种为磁暴峰期出现在高纬地区的大气密度突发性跃增,增变比高达5.5.后者存在着区域上的不对称性及时间上的突发性和增幅的差异.此次强磁暴峰期还同时出现了南北半球高纬地区的大气密度跃增双峰.同时还表明这种增变峰可能存在着由高纬向低纬地区迅速推移的现象,在中纬地区推移速度可达15°/h(纬度)左右.

Disturbance of the Upper Atmospheric Density During August 24, 2005 Severe Geomagnetic Storm Event

During 2005 the Solar activity level was very low, since this year February the monthly mean F10.7 < 100. At August 24 a severe geomagnetic storm event (Kp = 9) occurred with a sudden commencement. This is a good case for the analysis of the influence of a severe geomagnetic storm on the density of the upper atmosphere. In this paper the measured data of the satellite borne atmospheric density detector. From analyzing these measurements the following results were concluded. During this severe geomagnetic storm event, the atmospheric density showed strong disturbances. There are two responses, one is a global thermosphere density enhancement follow the variations of the geomagnetic disturbance, the responding processes were 6 hours late after the geomagnetic disturbance started, the biggest change ratio is 2.5. Another is abnormal density disturbance at high latitude areas during the peak period of geomagnetic disturbances, the biggest change ratio is 5.5, and with an asymmetry feature for the sauthern and northern hemispheres. In situ measurements also show that traveling of the atmospheric density disturbance from high latitude to lower latitude region very fast, the velocity is about 15?(latitude)/h at middle latitude region.