We statistically investigate the spectral scalings of magnetic fluctuations at the upstream and downstream regions near the Venusian bow shock and perform a differentiation by shock geometry. Based on the Venus Express data, 115 quasi-parallel ( $$Q_{\parallel }$$ Q ‖ ) bow shock crossings and 303 quasi-perpendicular ( $$Q_{ \bot }$$ Q ⊥ ) bow shock crossings are selected. The statistical results suggest that the bow shock tends to modify the upstream spectra flatter to 1/ f noise in the magnetohydrodynamics (MHD) regime and steeper to turbulence in the kinetic regime after the magnetic fluctuations crossing the bow shock, and this modification for the $$Q_{\parallel }$$ Q ‖ and $$Q_{ \bot }$$ Q ⊥ bow shocks is basically consistent. However, the upstream spectral scalings are associated with the shock geometry. The changes of the spectral scalings of magnetic fluctuations near the $$Q_{\parallel }$$ Q ‖ bow shocks are not as significant as near the $$Q_{ \bot }$$ Q ⊥ bow shock crossings. That might result from the fluctuations generated by the backstreaming ions which can escape across the $$Q_{\parallel }$$ Q ‖ bow shock into the foreshock. Our results suggest that the energy cascade and dissipation near Venus can be modified by the Venusian bow shock, and the $$Q_{\parallel }$$ Q ‖ bow shock plays an important role on the energy injection and dissipation in the solar wind interaction with Venus. The large dispersion of spectral scalings indicates that this fluctuation environment is complicated, and the shock geometry is not the only key factor in the fluctuations across the Venusian bow shock. Other possible factors in the shock modification to the upstream fluctuations will be explored in future.

中文翻译：

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金星弓形激波上游和下游磁涨落的光谱标度

我们对金星弓形激波附近的上游和下游区域的磁涨落的频谱尺度进行了统计研究，并通过激波几何学进行了区分。根据金星快车的数据，选择了 115 个准平行（ $$Q_{\parallel }$$ Q ‖ ）弓激波交叉点和 303 个准垂直（ $$Q_{ \bot }$$ Q ⊥ ）弓激波交叉点. 统计结果表明，在磁流体动力学 (MHD) 状态下，弓形激波倾向于将上游频谱修改为更平坦的 1/ f 噪声，并且在磁波动穿过弓形激波后，在动力学状态中更陡峭到湍流，并且这种修改对于 $ $Q_{\parallel }$$ Q ‖ 和 $$Q_{ \bot }$$ Q ⊥ 弓形震荡基本一致。然而，上游频谱比例与激波几何相关。$$Q_{\parallel }$$ Q ‖弓形激波附近磁涨落谱标度的变化不如$$Q_{ \bot }$$ Q ⊥ 弓形激波附近显着。这可能是由回流离子产生的波动引起的，这些离子可以穿过 $$Q_{\parallel }$$Q ‖ 弓形激波进入前激波。我们的研究结果表明，金星附近的能量级联和耗散可以被金星弓形激波改变，而 $$Q_{\parallel }$$ Q ‖弓形激波对太阳风相互作用中的能量注入和耗散起着重要作用与金星。光谱尺度的大分散表明这种波动环境是复杂的，激波几何并不是金星弓形激波波动的唯一关键因素。