Modeling the ionospheric prereversal enhancement by using coupled thermosphere‐ionosphere data assimilation
Modeling the ionospheric prereversal enhancement by using coupled thermosphere‐ionosphere data assimilation
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DOI：
10.1002/2016gl071812
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发表时间：
2017-02
影响因子：
5.2
通讯作者：
Chia‐Hung Chen;C. Lin;Wei-han Chen;T. Matsuo
中科院分区：
文献类型：
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作者：
Chia‐Hung Chen;C. Lin;Wei-han Chen;T. Matsuo
本文报道了利用集合卡尔曼滤波将总电子含量（TEC）同化到热层-电离层耦合模型中，改进了东向前向增强（PRE）电场（E场）的规范和预报。通过数据同化，同时调整电离层等离子体密度、热层风、温度和成分。日侧PRE - E场计算较前一状态的改善主要是通过东风增强实现的。改进后的E场计算增强了等离子体喷泉，加深了赤道槽。结果表明，由于黄昏时纬向电子密度梯度增大和离子阻力减小，Pedersen电导率水平梯度增大，东风水平梯度增大。这种修正提供了较好的条件，并获得了更接近观测值的增强PRE星等。PRE - E场的调整是通过模型捕获的自洽热层和电离层耦合过程实现的。该研究表明，在10 min循环周期内的tec同化可以更好地预测赤道等离子体夜间不稳定的PRE - E场。
We report that assimilating total electron content (TEC) into a coupled thermosphere‐ionosphere model by using the ensemble Kalman filter results in improved specification and forecast of eastward prereversal enhancement (PRE) electric field (E field). Through data assimilation, the ionospheric plasma density, thermospheric winds, temperature, and compositions are adjusted simultaneously. The improvement of duskside PRE E field calculation over the prior state is achieved primarily by intensification of eastward neutral wind. The improved E field calculation promotes a stronger plasma fountain and deepens the equatorial trough. As a result, the horizontal gradients of Pedersen conductivity and eastward wind are increased due to greater zonal electron density gradient and smaller ion drag at dusk, respectively. Such modifications provide preferable conditions and obtain a strengthened PRE magnitude closer to the observation. The adjustment of PRE E field is enabled through self‐consistent thermosphere and ionosphere coupling processes captured in the model. This study suggests that the PRE E field that is critical in driving the evening equatorial plasma instability could be better forecasted by assimilation of TECs in the 10 min cycling.