海南VHF雷达观测到的低纬F区电离层场向不规则体事件分析

摘要

Hainan VHF radar has the rapid scan observation capability of two-dimensional imaging of ionospheric irregularities,which is essential for investigating the generation and evolution of FieldAligned Irregularities (FAI).In this study,the ionospheric irregularities observed by Hainan VHF radar on the night of Oct.27,2011 have been analyzed.The main results show that the observed irregularities can be divided into three stages.In the initial formation stage,the irregularities appear very weak and develop very slowly,which mainly expand upward and last for about 14 minutes.In the expansion and enhancement stage,the irregularities rapidly expand and develop both in upward and zonal directions,which last for about 14 minutes.The intensity of irregularities early increases rapidly and later slightly decreases.The spatial scale of irregularities exceeds more than 200km.In the stage of eastward drift and leaving,the intensity of irregularities further decreases,and the expansion area reaches the maximum.It mainly shows the eastward drift and last for nearly 30 minutes.This observation firstly gives the formation and development processes of ionospheric irregularities over the Hainan region,which seems to be quite different from that of other regions.%中国海南VHF雷达具有快速扫描观测及对电离层不规则体进行二维成像的能力.采用时间序列上的连续观测,可以获得场向不规则体发展变化的一系列二维空间图像.本文对海南VHF雷达2011年10月27日夜间观测到的电离层不规则体事件进行分析,主要结果表明,本次观测到的不规则体可分为三个阶段.在初步形成阶段,不规则体开始出现时非常微弱,发展变化很慢,主要表现为向上可扩展,持续时间约14 min.在扩大增强阶段,不规则体快速向上并向两侧扩展,持续时间约14min;不规则体强度前期迅速增大,后期略有减弱,空间尺度达200 km以上.在东漂离开阶段,不规则体强度进一步减弱,扩展面积达到最大,主要表现为东向漂移,持续时间近30 min.这次观测首次给出了海南地区上空电离层不规则体的形成和发展过程.结合其他台站的观测进行对比分析发现,海南观测到的雷达羽与其他地区的雷达羽具有明显不同,海南地区的雷达羽特性及其对应的物理过程有待进一步观测研究.