Asymmetric distribution of the ionospheric electric potential in the opposite hemispheres as inferred from the SuperDARN observations and FAC-based convection model

We compare the SuperDARN convection patterns with the predictions of a new numerical model of the global distribution of ionospheric electric potentials. The model utilizes high-precision statistical maps of field-aligned currents (FAC) derived from measurements made by polar-orbiting low-altitude satellites. Both the solar and auroral precipitation contributions are included in order to derive the ionospheric conductance. Taking into account the electrodynamic coupling of the opposite hemispheres, the model allows one to obtain the convection patterns developed simultaneously in both hemispheres for given input parameters. SuperDARN, with its database containing global northern and southern convection maps, provides the unique opportunity to compare the model predictions of electric fields with observations. In the present study we focus on the effect of significant interhemispheric asymmetry governed by the IMF clock angle and solar zenith angle. We calculate the convection patterns for specific cases caused by the sign of B_Y and season and demonstrate the capability of the FAC-based model reproduce the radar observations. The simulation confirms that the solar zenith angle should be linked to the IMF clock angle to fully characterize the convection patterns. The model predicts that the cross-polar cap potential drop is regularly larger in the winter hemisphere than in the summer hemisphere.     

一次行星际磁场南向突变的高纬电离层对流响应特征

本文利用北半球的超级双极光雷达网数据,考察了一次行星际磁场南向突变时高纬电离层对流的响应特征,着重分析了响应的时间尺度. 对所研究的事件,行星际磁场南北分量在1.5 min内从+7 nT突变到-8 nT,而在突变前后约40 min内都保持相对稳定. 结果表明,电离层对流的初始响应发生在磁正午附近,相对于行星际磁场突变到达磁层顶的时间有大约3 min的滞后;响应与磁地方时有明显依赖关系,离磁正午越远,响应的滞后时间越长,晨昏两侧的对流响应比磁正午滞后约6 min,磁午夜的对流响应比磁正午滞后约12 min;对流重新趋于稳定的时间与磁地方时没有明显的依赖关系,该时间尺度约为10～14 min.     

基于深度学习的SuperDARN雷达极区电离层对流电势模型构建及预测

电离层等离子体对流是表征电离层电动力学的重要现象,对空间天气有着重要的指示作用.SuperDARN雷达网是研究中高纬电离层对流的重要手段,也是获得对流电势数据的重要来源.本文基于SuperDARN雷达12月份的对流电势数据,采用BP模型、FC-LSTM模型以及ED-ConvLSTM时空序列模型构建了高纬电离层等离子体对...