Long lead‐time space‐weather forecasting requires accurate prediction of the near‐Earth solar wind. The current state of the art uses a coronal model to extrapolate the observed photospheric magnetic field to the upper corona, where it is related to solar wind speed through empirical relations. These near‐Sun solar wind and magnetic field conditions provide the inner boundary condition to three‐dimensional numerical magnetohydrodynamic (MHD) models of the heliosphere out to 1 AU. This physics‐based approach can capture dynamic processes within the solar wind, which affect the resulting conditions in near‐Earth space. However, this deterministic approach lacks a quantification of forecast uncertainty. Here we describe a complementary method to exploit the near‐Sun solar wind information produced by coronal models and provide a quantitative estimate of forecast uncertainty. By sampling the near‐Sun solar wind speed at a range of latitudes about the sub‐Earth point, we produce a large ensemble (N = 576) of time series at the base of the Sun‐Earth line. Propagating these conditions to Earth by a three‐dimensional MHD model would be computationally prohibitive; thus, a computationally efficient one‐dimensional “upwind” scheme is used. The variance in the resulting near‐Earth solar wind speed ensemble is shown to provide an accurate measure of the forecast uncertainty. Applying this technique over 1996–2016, the upwind ensemble is found to provide a more “actionable” forecast than a single deterministic forecast; potential economic value is increased for all operational scenarios, but particularly when false alarms are important (i.e., where the cost of taking mitigating action is relatively large).

中文翻译：

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使用简单的一维“逆风”方案，使用近太阳条件的大集合进行概率太阳风预报。

长时间的提前期空间天气预测需要对近地太阳风的准确预测。当前的现有技术使用日冕模型将观测到的光球磁场外推到上部电晕，在这里它通过经验关系与太阳风速相关。这些近日太阳风和磁场条件为直到1 AU的三维大气层磁流体动力学（MHD）三维数值模型提供了内部边界条件。这种基于物理学的方法可以捕获太阳风中的动态过程，这些过程会影响近地空间中的结果条件。但是，这种确定性方法缺乏对预测不确定性的量化。在这里，我们描述了一种补充方法，可以利用日冕模型产生的近太阳太阳风信息，并提供对预测不确定性的定量估计。通过在次地球点附近的纬度范围内对近太阳太阳风速进行采样，我们产生了一个大的合奏（N  = 576）时间序列在太阳地球线的底部。通过三维MHD模型将这些条件传播到地球上在计算上是禁止的。因此，使用了计算有效的一维“逆风”方案。结果表明，近地太阳风速系综的方差可提供预报不确定性的准确度量。在1996年至2016年间应用此技术，发现上风集合提供的预测要比单一确定性预测更具“实用性”。在所有操作场景下，潜在的经济价值都会增加，尤其是在虚假警报很重要的情况下（即，采取缓解措施的成本相对较高时）。