全球电离层TEC起伏特性分析

利用全球电离层TEC地图（GIMs）数据，在已经建立TEC气候学模式的基础上，计算了1998年以来固定UT时间的全球TEC起伏指数σ_DGEC．采用偏相关分析方法对σ_DGEC与太阳活动（F107指数）及其起伏（dF107）、地磁活动（Ap指数）、季节变化因子（太阳偏置角）等因素，以及上述因素的非线性组合等的相关性进行分析，发现σ_DGEC与F107、Ap指数具有最强的相关性，与F107指数和半年变化因子的交叉项F107×S、F107指数的二次方具有较好的相关性，同时，与F107指数与年变化因子的交叉项F107×A及F107扰动指数偏离值（dF107）的二次方也具有一定的相关性．据此，以这些因子作为驱动量，建立了σ_DGEC的多元回归模型．鉴于σ_DGEC反映全球范围内电离层TEC起伏的平均特性，并与太阳活动F107指数、地磁活动Ap指数具有良好的相关性，为此我们建议，将全球TEC相对起伏指数σ_DGEC作为描述全球电离层扰动状态及电离层天气特征的一个新参量．

A global ionospheric TEC perturbation index

The global perturbation index, σ_DGEC, of the total electron density (TEC) was estimated from the global ionospheric maps (GIMs) produced by Jet Propulsion Laboratory (JPL). With the use of the Partial Correlation Analysis method we analyze the correlation between the global TEC perturbation index and several other factors such as the solar radio flux at 10.7 cm (F107) and its perturbation (dF107), the geomagnetic Ap index, as well as the seasonal factors. The result reveals that σ_DGEC is much correlated with F107 and Ap, it is also correlated with the products of different factors, such as F107×S , F107²,F107×A and dF107². Thus, we choose these factors and their multipliers to create a multiple regression model of σ_DGEC. The index σ_DGEC may efficiently represent the characteristics of the global TEC perturbation and strongly correlates with the solar activity and the magnetic disturbance. Thus, it is suggested that the global TEC perturbation index σ_DGEC be chosen as a new parameter in describing the ionospheric disturbances, especially the state of the space weather in the ionosphere.