中国区域电离层TEC与月均值偏差的空间相关性研究

A study of spacial correlation of monthly mean deviation of ionospheric TEC over China

本文利用美国喷气动力实验室(JPL)提供的电离层总电子含量(TEC)的地图网格产品,计算了中国区域上空电离层TEC与月均值偏差及其空间相关系数矩阵,从而分析了TEC与月均值偏差空间相关性的分布特征,根据统计学中定义的相关距离提取了这种偏差在经、纬度方向上的空间特征尺度.并以2008年和2011年为例,着重考察了TEC月偏差的空间特征尺度与太阳活动水平、地磁条件和季节变化之间的关系.结果发现,TEC与月均值偏差的空间相关性呈现椭圆形高斯分布的特征,沿纬线方向的特征尺度大于沿经线方向,不同纬度区域偏差的空间相关性特征差异明显,高纬的特征尺度在两个方向上均小于低纬,而不同经度区域在相同地方时条件下表现差异不大;两个方向的特征尺度在白天、太阳活动水平高和地磁活动剧烈时均存在增大的现象.

Using the the ionospheric total electron content （TEC） map grid products provided by the Jet Propulsion Laboratory （JPL）, we calculate the deviation of the TEC to the monthly- averaged TEC over China. Spatial correlation coefficient matrix of the deviation is also calculated to analyze its distribution characteristic. According to the definition of correlation distance in statistics, we extract the spatial characteristic scales in the zonal and meridian directions. Taking the example of 2008 and 2011, we further analyze the dependence of such spatial characteristic scales on the aolar activity level, geomagnetic conditions, and seasons. The results show that the spatial correlation approximately obeys the elliptic Gaussian distribution; the spatial characteristic scale in the zonal direction is larger than that in the meridian direction; the spatial correlationcharacteristics change significantly with the latitude~ the scales at high latitudes is smaller than those at low latitudes in both directions; the areas with the same local time but different longitudes have little differences;the characteristic scales in both directions tend to be larger when it′s in the daytime, of high solar activity level, and in high intense magnetic activity.