An inner boundary condition for solar wind models based on coronal density
An inner boundary condition for solar wind models based on coronal density
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DOI：
10.1051/swsc/2022026
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发表时间：
2022-07
影响因子：
3.3
通讯作者：
K. A. Bunting;H. Morgan
中科院分区：
文献类型：
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作者：
K. A. Bunting;H. Morgan
随着社会越来越依赖易受空间气象事件影响的技术，对太阳风的准确预报变得越来越重要。这项工作描述了一个内边界条件的太阳风模型的基础上获得的日冕等离子体密度从日冕观测的层析成像地图，提供了一种新的替代磁外推。断层密度图提供了一个直接的约束日冕结构在日心距离为4至8 Rs，从而避免了需要模拟复杂的非径向低日冕。一个经验的逆关系将密度转换为太阳风的速度，太阳风的速度被用作内边界条件的日光层逆风外推（HUXt）模型，以给出在地球上的环境太阳风的速度。动态时间规整（DTW）算法被用来量化层析成像/HUXt输出和原位数据之间的协议。然后使用穷举搜索方法来调整下边界速度范围，以优化模型。早期的结果表明，40%的测量和建模的速度之间的平均绝对误差减少相比，耦合MAS/HUXt模型。因此，使用从断层摄影获得的密度图作为内部边界约束是日冕磁模型的有效替代方案，并提供了一个显着的进步，在该领域的常规天基日冕观测的可用性。
Accurate forecasting of the solar wind has grown in importance as society becomes increasingly dependent on technology that is susceptible to space weather events. This work describes an inner boundary condition for ambient solar wind models based on tomography maps of the coronal plasma density gained from coronagraph observations, providing a novel alternative to magnetic extrapolations. The tomographical density maps provide a direct constraint of the coronal structure at heliocentric distances of 4 to 8 Rs, thus avoiding the need to model the complex non-radial lower corona. An empirical inverse relationship converts densities to solar wind velocities which are used as an inner boundary condition by the Heliospheric Upwind Extrapolation (HUXt) model to give ambient solar wind velocity at Earth. The dynamic time warping (DTW) algorithm is used to quantify the agreement between tomography/HUXt output and insitu data. An exhaustive search method is then used to adjust the lower boundary velocity range in order to optimize the model. Early results show a 40% decrease in mean absolute error between measured and modelled velocities compared to that of the coupled MAS/HUXt model. The use of density maps gained from tomography as an inner boundary constraint is thus a valid alternative to coronal magnetic models, and offers a significant advancement in the field given the availability of routine space-based coronagraph observations.