利用卫星和GPS观测研究低纬局部等离子体浓度增强现象

本文同时利用DMSP、ROCSAT-1卫星数据和地基的GPS观测数据,研究一种与低纬等离子体泡相伴随的局部等离子体浓度增强现象.地基GPS的观测表明电离层总电子含量(TEC)也能反映这种等离子体浓度增强.通过4个观测事例的详细分析表明:这种等离子体浓度增强主要出现在磁纬±10°～±20°的局部区域,有时在近磁赤道区和中纬地区的电离层顶部也能观测到;与等离子体泡的出现规律相似,这种等离子体浓度增强主要出现在地方时21∶00以后,并在午夜后也能观测到.当等离子体浓度增强和等离子体泡发生时,在午夜前一般对应着背景垂直速度明显向上的扰动,在午夜后一般处于等离子体垂直速度下降至反向前的时间段,表明东向电场对于低纬不规则体的产生有非常重要的作用.

The case studies about the localized plasma density enhancement at low latitude from satellite and GPS observations

The phenomena of localized plasma density enhancements are studied using the plasma density data from DMSP F15 satellite, ROCSAT-1 satellite and the dual-frequency GPS data from IGS receivers at low latitude. The observation of GPS-TEC can also reflect this kind of plasma density enhancement. The four case studies indicate that this kind of plasma density enhancements is mainly located at about ±10°～±20° magnetic latitude region, while the plasma density enhancements can also occasionally occur at the topside ionosphere near the magnetic equator. Similar to plasma bubbles, the localized plasma density enhancement often occurred after 21∶00LT. It also can be observed at post-midnight. The observation indicates that plasma density enhancements occur when the vertical drift velocity has an upward perturbation at pre-midnight, or before the vertical downward drift velocity reversed at post-midnight. It is suggested the eastward electric field plays an important role in the production of the plasma density enhancements and plasma bubbles.