Accurate representation of ensemble members of coupled Ionosphere-Thermosphere (I-T) is crucial to the ionosphere forecast in the ensemble Kalman filter (EnKF) data assimilation system. In this paper, besides the model drivers used in previous studies, including the solar 10.7 cm radio flux (F10.7), auroral hemispheric power (HP) and cross-tail potential drop (CP), the eddy diffusion coefficient (ED), and nighttime vertical O⁺ flux at the top boundary are also perturbed to generate ensemble members. Based on our developed EnKF data assimilation system, the impact of perturbing different model external forcing parameters on ensemble generation and forecast capability of ionosphere and thermosphere has been investigated in detail through a series of sensitivity tests and data assimilation experiments. This system uses the National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) as a background model. The findings are summarized as follows: (a) Associated with perturbing two additional model forcing parameters, better ensemble members of ionosphere and thermosphere states of the background model can be generated during both daytime and nighttime. (b) The improvement of the forecast capability of the ionosphere and thermosphere variables can be further enhanced. This study can provide a reference for ensemble generating strategy for the coupled I-T EnKF data assimilation in the future.

中文翻译：

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扰动涡扩散和上边界对电离层EnKF同化系统的影响

准确表示耦合电离层-热层 (IT) 的集合成员对于集合卡尔曼滤波器 (EnKF) 数据同化系统中的电离层预测至关重要。在本文中，除了之前研究中使用的模型驱动因素，包括太阳 10.7 cm 射电通量 (F10.7)、极光半球功率 (HP) 和横尾电位降 (CP)、涡流扩散系数 (ED)、和夜间垂直 O ⁺顶部边界的通量也受到扰动以生成整体成员。基于我们开发的EnKF数据同化系统，通过一系列敏感性测试和数据同化实验，详细研究了扰动不同模式外强迫参数对电离层和热层集合生成和预报能力的影响。该系统使用美国国家大气研究中心 (NCAR) 热层电离层电动力学一般环流模型 (TIEGCM) 作为背景模型。研究结果总结如下： (a) 与扰动两个额外的模型强迫参数相关，可以在白天和夜间生成背景模型的电离层和热层状态的更好集合成员。(b) 可以进一步提高电离层和热层变量的预报能力。该研究可为未来耦合IT EnKF数据同化的集成生成策略提供参考。