标题： 湍流强度对摆动磁力线和太阳高能粒子事件范围的影响 显示英文标题

标题： The effect of turbulence strength on meandering field lines and Solar Energetic Particle event extents

摘要： 对太阳高能粒子（SEP）传播过程的理解对于了解太阳爆发如何影响近地空间的辐射环境至关重要。 SEP的传播受到太阳风中湍流磁场的影响，导致SEPs向地球的随机传输。 多航天器观测表明，跨场传播强烈地塑造了地球处的SEP通量。 然而，仅通过空间扩散来模拟SEP的跨场传输已被证明是不足的，除非使用不切实际的大跨场扩散系数。 最近的研究表明，在湍流中，能量粒子沿平均场方向的早期传播并不是扩散性的，因为粒子沿着蜿蜒的场线传播。 这种早期传输模式导致粒子快速穿越平均场方向，这与SEP观测结果一致。 在本研究中，我们展示了湍流强度对近地SEP辐射环境演变的重要性。 我们利用一个由1 AU处的SEP平行散射平均自由程$\lambda_{\parallel}^{*}$参数化的湍流传输模型计算传输参数，并表明平行和跨场传输是相关的，导致缓慢平行传输的条件对应于更宽的事件。 我们发现了一个用于最大强度经度分布高斯拟合的标度$\sigma_{\phi,\, \mathrm{max}}\propto (1/\lambda_{\parallel}^{*})^{1/4}$。 在强散射条件下，最高强度的经度向西偏移。 我们的结果强调了理解SEP传输和行星际湍流条件对于建模和预测地球处SEP辐射环境的重要性。 显示英文摘要

摘要： Insights into the processes of Solar Energetic Particle (SEP) propagation are essential for understanding how solar eruptions affect the radiation environment of near-Earth space. SEP propagation is influenced by turbulent magnetic fields in the solar wind, resulting in stochastic transport of SEPs to Earth. Multi-spacecraft observations suggest that the cross-field propagation shapes the SEP fluxes at Earth strongly. However, modelling SEP cross-field transport as spatial diffusion has been shown to be insufficient without use of unrealistically large cross-field diffusion coefficients. Recent work has shown that the early-time propagation of energetic particles across the mean field direction in turbulent fields is not diffusive, as the particles propagating along meandering field lines. This early-time transport mode results in fast access of the particles across the mean field direction, in agreement with the SEP observations. In this work, we demonstrate the significance of turbulence strength on evolution of the SEP radiation environment near Earth. We calculate the transport parameters with a turbulence transport model, parametrised by the SEP parallel scattering mean free path at 1~AU, $\lambda_{\parallel}^{*}$, and show that the parallel and cross-field transport are connected, with conditions resulting in slow parallel transport corresponding to wider events. We find a scaling $\sigma_{\phi,\, \mathrm{max}}\propto (1/\lambda_{\parallel}^{*})^{1/4}$ for the Gaussian fitting of the longitudinal distribution of maximum intensities. The longitudes with highest intensities are shifted towards the west for strong scattering conditions. Our results emphasise the importance of understanding both the SEP transport and the interplanetary turbulence conditions for modelling and predicting the SEP radiation environment at Earth.