Both coronal holes and active regions are source regions of the solar wind. The distribution of these coronal structures across both space and time is well known, but it is unclear how much each source contributes to the solar wind. In this study we use photospheric magnetic field maps observed over the past four solar cycles to estimate what fraction of magnetic open solar flux is rooted in active regions, a proxy for the fraction of all solar wind originating in active regions. We find that the fractional contribution of active regions to the solar wind varies between 30% to 80% at any one time during solar maximum and is negligible at solar minimum, showing a strong correlation with sunspot number. While active regions are typically confined to latitudes ±30^∘ in the corona, the solar wind they produce can reach latitudes up to ±60^∘. Their fractional contribution to the solar wind also correlates with coronal mass ejection rate, and is highly variable, changing by ±20% on monthly timescales within individual solar maxima. We speculate that these variations could be driven by coronal mass ejections causing reconfigurations of the coronal magnetic field on sub-monthly timescales.

日冕洞和活动区都是太阳风的源区。这些日冕结构在空间和时间上的分布是众所周知的，但尚不清楚每个来源对太阳风的贡献有多大。在这项研究中，我们使用在过去四个太阳周期中观察到的光球磁场图来估计有多少磁开放太阳通量植根于活动区域，代表所有太阳风起源于活动区域的比例。我们发现活动区域对太阳风的部分贡献在太阳活动极大期的任何时间都在 30% 到 80% 之间变化，而在活动极小期时可以忽略不计，显示出与太阳黑子数量的强相关性。虽然活动区域通常限于纬度 ±30 ^∘在日冕中，它们产生的太阳风可以到达纬度高达±60 ^∘。它们对太阳风的部分贡献也与日冕物质抛射率相关，并且变化很大，在单个太阳极大值内的每月时间尺度上变化 ±20%。我们推测这些变化可能是由日冕物质抛射引起的，导致日冕磁场在次月时间尺度上重新配置。