强磁暴期间TIEGCM模式与CHAMP卫星热层大气密度的比较分析

Comparison and Analysis of the Thermospheric Density between TIEGCM and CHAMP during a Severe Geomagnetic Storm

利用NCAR-TIEGCM模式计算了2003年11月20—21日强磁暴期间410km高度上的大气密度，并与CHAMP／STAR加速度计反演数据进行对比和分析．结果表明，模式结果能够准确反映磁暴期间大气密度的分布和变化情况，与实测结果在变化趋势和量级上具有较好的一致性，但在精细结构和数值大小上仍存在一定差异．模式低估了磁暴期间大气密度的增幅，实测大气密度增幅高达250％-400％，而模式结果为100％-125％．模式结果与实测数据的偏差在高纬地区高于低纬地区，日侧高于夜侧．通过模式和实测数据的分析发现，磁暴期间大气密度扰动具有日夜侧和南北半球不对称性．此外，模式能够准确反映磁暴期间大气密度扰动从高纬向低纬的传播以及大气密度对SYM—H指数响应的延迟特性．

The thermospheric densities at the altitude of 410km during the geomagnetic storm on Nov. 20--21, 2003 are calculated by NCAR-TIEGCM model, and the results are compared and ana- lyzed with the observational data from CHAMP/STAR. The results show that the model can exactly represent the distribution and variation of the density during geomagnetic storm, and the model results have a good consistency with the CHAMP data in trends and orders. But some differences do exist in detailed structure and magnitude. The model underestimated the increases of the density during geomagnetic storm with the values of 100%~125%, instead of the 250%~400% observed by CHAMP. The deviations between the model and CHAMP at high latitude are bigger than those of low latitude, and dayside bigger than nightside. It is also found that the density disturbance during geomagnetic storm presents day-night asymmetry and Southern-Northern hemisphere asymmetry. The model can exactly represent the propagation of the density disturbance from high latitude to low latitude, and the time delay in response of the density to geomagnetic storm.