对流输运在TOI断裂形成等离子体云块中的作用研究

The role of convection transport in TOI breaking into polar cap patches

极盖等离子体云块是极区电离层常见特征之一,其形成演化过程是当前重要研究课题.光电离高密度等离子体在对流输送作用下从日侧穿过极隙,通过极盖到达夜侧,已成为共识.日侧磁场重联作用下的极区对流输运过程,在舌状等离子体结构(TOI)“断裂”形成极盖等离子体云块中发挥重要作用.利用极区全域GPS/TEC观测数据,结合SuperDARN雷达实测的对流速度,对等离子体云块形成过程进行案例研究,重点分析两种TOI断裂形成等离子体云块的发生机制.研究结果显示,等离子体对流输运过程在TOI断裂形成等离子体云块过程中发挥关键性作用,对流形态或局部对流速度矢量急剧变化都可能导致TOI结构不稳定,使TOI结构断裂形成等离子体云块.

As a significant weather phenomenon in polar space,the polar cap patch formation is one of important issues.It is commonly considered that the high-density sunlit plasma can be transported from dayside,through cusp,over the polar cap,and eventually to the dawnside.Observations suggest that the strong convection flow due to the dayside magnetic reconnection has an important role in TOI(Tongue of ionization)“breaking off”,forming polar cap patches.Based on observations to polar GPS/TEC and SuperDARN convection,this paper analyzes the cases of polar cap patches formation process,focusing on two mechanisms of TOI breaking into polar cap patches.The results show that the plasma transportation takes a key role in TOI breaking into polar cap patches,and both the convection pattern and the rapid change of velocity of partial TOI can bring out instability,causing TOI breaking into polar cap patches.