We developed a new fitting method of a toroidal model for the analysis of interplanetary flux ropes (IFRs). The pitch angle of the magnetic field at the IFR boundary [ α p $\alpha_{\mathrm{p}}$ ] is fixed to 90 ∘ $90^{\circ}$ in the toroidal model of Romashets and Vandas ( Geophys. Res. Lett. 30 , 2065, 2003 ) (conventional method). To relax this condition for our method, the pitch angle was made one of the free parameters (generalized method). In this paper, we examine the difference between the results of these two toroidal IFR model fitting methods by applying them to magnetic-obstacle (MO) events observed by the Wind and Solar Terrestrial Relations Observatory (STEREO) spacecraft. We found that the generalized method gives an α p $\alpha_{\mathrm{p}}$ near 90 ∘ $90^{\circ}$ (within the range of 90 ∘ ± 30 ∘ $90^{\circ}\pm30^{\circ}$ ) for approximately 60% of events. Thus, the assumption in the conventional method that α p $\alpha_{\mathrm{p}}$ is 90 ∘ $90^{\circ}$ is valid for many cases. This also implies that many flanks of IFR have a magnetic field line nearly perpendicular to the IFR axis. We also found that the generalized method gives a similar normal direction of the torus plane and poloidal magnetic flux as the conventional method. However, the generalized method gives a toroidal magnetic flux that is significantly different from that given by the conventional method for a non-negligible number of events. Thus, we concluded that it is better to use the generalized method than the conventional method in order to get more accurate estimation of the toroidal magnetic flux of IFRs.

中文翻译：

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不同边界节距角处理​​的环形行星际磁通绳模型拟合的比较

我们开发了一种新的环形模型拟合方法，用于分析行星际磁通绳 (IFR)。在 IFR 边界 [ α p $\alpha_{\mathrm{p}}$ ] 处的磁场俯仰角在 Romashets 和 Vandas 的环形模型中固定为 90 ∘ $90^{\circ}$ ( Geophys. Res . Lett. 30 , 2065, 2003 )（常规方法）。为了放宽我们方法的这个条件，俯仰角被设为自由参数之一（通用方法）。在本文中，我们通过将这两种环形 IFR 模型拟合方法应用于风日地关系天文台 (STEREO) 航天器观测到的磁障碍 (MO) 事件，来检验这两种方法的结果之间的差异。我们发现广义方法给出了一个α p $\alpha_{\mathrm{p}}$ 接近 90 ∘ $90^{\circ}$（在 90 ∘ ± 30 ∘ $90^{\circ}\pm30^ 范围内） {\circ}$ ) 大约 60% 的事件。因此，传统方法中的假设 α p $\alpha_{\mathrm{p}}$ 是 90 ∘ $90^{\circ}$ 在许多情况下是有效的。这也意味着 IFR 的许多侧面都有一条几乎垂直于 IFR 轴的磁场线。我们还发现，广义方法给出了与传统方法相似的环面平面和极向磁通量的法线方向。然而，对于不可忽略数量的事件，广义方法给出的环形磁通量与传统方法给出的环形磁通量明显不同。因此，