不同高度和不同地磁扰动期间热层大气密度模式值与探测值的显著差异

热层大气密度是空间大气环境的重要参数,经过多年的研究已开发了多种大气模式,但其误差普遍较大,尤其在磁暴期间偏差值甚至超过100%.本文利用中国星载大气密度探测器和CHAMP卫星加速度计在轨获得的连续探测数据,针对近10年(2003—2014)中多次强磁暴事件和多次中等强度扰动事件,即2003年11月、2004年7月和2005年8~9月多次强磁暴事件(Kp值均达到9),2006年4月、2012年4月的两次中等强度磁暴事件(Kp值分别达到7和6),分析和比对不同强度磁扰事件期间不同高度全球大气密度就位探测值与模式值(NRLMSISE00)之间的差别.在2005年8月24日强磁扰事件中,560 km高度中国卫星就位探测值上涨幅度约2~3倍,扰动区中的增变比高达5.7倍,375 km高度CHAMP卫星就位探测值上涨幅度约0.8倍,扰动区中增变比达4.0倍,期间大气密度模式值不仅没有出现明显的涨落,更没有出现强烈的区域扰动;在2003年11月和2004年7月的强磁扰事件中,CHAMP卫星就位探测值均有显著涨变和强烈扰动变化,而模式值无明显扰动变化;在中等强度磁扰事件中,高度560 km附近就位探测值在北、南半球高纬地区显著上涨,远高于模式值,高度350 km附近就位探测值在地球阴影区域显著上涨,上涨幅度也大于模式值.分析结果表明现有大气模式对地磁扰动(尤其是强磁暴事件)期间全球热层大气密度的响应并不明显,需要进一步改善.

Significant difference of the thermospheric density between the model and observation values of satellite during different geomagnetic storm events and different altitudes

As an important parameter of space environment, thermospheric atmospheric density has been characterized by a variety of models after years of research. However, atmospheric model errors are generally large, and the deviation even excesses 100% especially during geomagnetic storm events. Comparison between the observation and model (NRLMSISE00) of global atmospheric density at different altitudes during magnetic disturbance events with various intensities is discussed in this paper. The observation data was obtained from Chinese in situ atmospheric density explorer and CHAMP satellite for nearly 10 years (2003—2014). Here we concentrate on the variations of atmospheric density during the four strong geomagnetic storm events (November 2003, July 2004, August 2005, and September 2005, Kp reached 9), and during two medium geomagnetic storm events (April 2006 and April 2012, Kp reached 7 and 6). The observation value of Chinese satellite rose by more than 2 to 3 times, and even up to about 5.7 times on August 24, 2005 when strong geomagnetic disturbance event occurred. The observation value of CHAMP satellite rose by more than 0.8 times, and even up to about 4.0 times on August 24, 2005 when strong geomagnetic disturbance event occurred. But the model data show neither obvious fluctuations nor strong regional disturbances. The observation value of atmospheric density at 560km had a significant rise in the high latitudes of the Northern and Southern hemisphere during medium-intensity geomagnetic disturbance, which was much higher than the model data. The observation data of atmospheric density at 350km also rose significantly in the Earth's nightside, which was also greater than the mode data. It is indicated that atmospheric models cannot respond well to the global strong atmospheric density disturbances during geomagnetic storms and it should be further improved.