利用掩星技术研究南极地区顶部电离层特性

Analysis of Topside Ionosphere in Antarctica Based on Radio Occultation

掩星观测能够提供地面到低轨卫星轨道高度处的整个电离层电子密度剖面,对于顶部电离层的研究有重要的作用。本文利用COSMIC(constellation observing system for meteorology ionosphere and climate)掩星数据反演了电子密度剖面,提取了F2层峰值高度(hmF2)、F2层峰值密度(NmF2)、垂直标尺高(vertical scale height,VSH)等电离层参数,研究了南极地区的F2层在太阳活动周期内的变化、年际变化、周日变化等,并且重点分析了南极地区的顶部电离层的垂直结构特征,尤其是威德尔海异常在垂直方向上的变化。结果表明,整个南极的hmF2每日均值在250~300km左右,NmF2每日均值在1~8×1011 el/m3之间,VSH每日均值在100~250km,威德尔海异常主要表现在顶部电子密度的增强和底部电子密度的减少。

Radio occultation can provide the ionospheric electron density profile from the ground to the height of LEO orbit,which play an important role in the research of topside ionosphere.In this paper,COSMIC(Constellation Observing System for Meteorology Ionosphere and Climate)radio occultation data are used to obtain the electron density profile,and the ionospheric parameters,such as hmF2(peak height of F2layer),NmF2(peak electron density of F2layer),VSH(vertical scale height),are extracted.The changes of F2 layer in Antarctica are studied in the solar activity cycle,annual cycle and diurnal cycle,respectively.The vertical structure characteristics of top ionosphere in Antarctica,especially for Weddell Sea anomaly,are studied in detail.The results show that the daily averages of the whole Antarctic hmF2,NmF2 and VSH are 250 km,(1-4)× 1011el/m3,100~200km,respectively,during low solar activity,and up to 250-300 km,(1-8)× 1011el/m3,150-250 km,respectively,during high solar activity.Weddell Sea Anomaly is mainly characterized by the electron density enhancement at the top and the electron density reduction at the bottom,which lasts four months,from late spring to early autumn.