2014—2016年FY-3C与COSMIC掩星电离层特征参数的比较

Comparison of ionospheric characteristic parameters retrieved from FY-3C and COSMIC radio occultation during 2014 to 2016

利用由FY-3C和COSMIC两个全球导航卫星系统无线电掩星任务提供的2014—2016共3年的电离层电子密度廓线,基于时间间隔7. 5 min、经纬度间隔2. 5°的时空匹配窗口,对两个掩星任务的电离层峰值密度(NmF2)和峰值高度(hm F2)进行了比较。结果表明:由两个任务得到的特征参数相关性良好,各年之间相关性水平基本稳定,其中各年NmF2和hm F2相关系数的平均值分别为0. 87和0. 75; FY-3C的特征参数相对于COSMIC的偏差很小,各年NmF2的绝对偏差均值和相对偏差均值分别不超过±0. 25×10~5el/cm^3和±15. 0%,hm F2的绝对偏差均值和相对偏差均值分别不超过±7. 00 km和±1. 80%。此外,由两个任务得到的特征参数在空间上均表现出赤道及低纬地区数值较高且呈"条带状"分布的特点,且两个任务都监测到了2016年相对于2014年和2015年NmF2和hm F2均存在显著下降的现象。

The ionospheric EDPs(electron density profiles)obtained during 2014 to 2016 from two GNSS(global navigation satellite system)RO(radio occultation)missions,the FY-3C mission and the COSMIC mission,were used to compare the ionospheric peak density NmF2 and the ionospheric peak height hmF2 of two missions under the collocation criterion with the time window of 7.5 min and the space window of 2.5°.The results show that the peak parameters derived from the two RO missions are highly correlated,with the yearly average correlation coefficient of NmF2 and hmF2 being 0.87 and 0.75,respectively.The biases of the peak parameters derived from the two RO missions are very small,with the absolute and the relative bias of NmF2 and hmF2 being less than±0.25×105 el/cm3and±15.0%,and±7.00 km and±1.80%,respectively.In addition,the stripshaped spatial distributions of the two ionospheric characteristic parameters from both of the two RO missions show that the values of NmF2 and hmF2 are larger in the areas of the equator and low latitudes than in other regions,and that the values of NmF2 and hmF2 decline significantly in 2016 compared with 2014 and 2015.