Abstract. It has been suggested from observations that the 11-year solar cycle influences regional tropospheric temperature and circulation relatively symmetrically around the equator. During periods of low (high) solar activity, the mid-latitude storm tracks are weakened (strengthened) and shifted towards the equator (poles). The mechanisms behind solar influence on climate are still debated and evidence from paleoclimate records often lacks precise dating required for assessing the global context. Well-dated proxy-based evidence for solar activity and natural climate change exist for the Northern Hemisphere, suggesting pattern similar to today for periods of grand solar minima. However, well-dated and high-resolution terrestrial climate reconstructions are lacking for the Southern Hemisphere. Here we present a unique precisely dated record for past changes in humidity and windiness from the Crozet archipelago at 46° S in the Southern Indian Ocean, a site strongly influenced by the westerly wind belt. We find an increased influence of the westerly winds shortly after 2800 cal year BP synchronous with a major decline in solar activity and significant changes in Northern Hemisphere mid-latitude wind and humidity records. Supported by a general circulation model run encompassing a grand solar minimum, we infer that periods of low solar activity are connected to an equator-ward shift of the mid-latitude westerly wind belts in both hemispheres comparable to the climate reaction to 11-year solar cycle variability inferred from reanalysis data. We conclude that solar forcing is connected to the bipolar climate response about 2800 years ago through synchronous changes in atmospheric circulation of similar sign in both hemispheres.

中文翻译：

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西风带对太阳强迫的南北半球同步响应

摘要。观测表明，11 年的太阳活动周期对赤道周围区域对流层温度和环流的影响相对对称。在低（高）太阳活动期间，中纬度风暴路径减弱（加强）并向赤道（两极）移动。太阳对气候影响背后的机制仍在争论中，来自古气候记录的证据往往缺乏评估全球环境所需的精确年代。北半球存在关于太阳活动和自然气候变化的过时的代理证据，表明大太阳极小期的模式与今天相似。然而，南半球缺乏过时和高分辨率的陆地气候重建。在这里，我们展示了南印度洋南印度洋南纬 46° 的克罗泽群岛过去湿度和风力变化的独特精确日期记录，该地点受西风带的影响很大。我们发现在 2800 cal year BP 之后不久西风的影响增加，与太阳活动的大幅下降和北半球中纬度风和湿度记录的显着变化同步。在包含大太阳活动极小期的一般环流模型的支持下，我们推断太阳活动低的时期与两个半球中纬度西风带的赤道移动有关，这与气候对 11 年太阳活动的反应相当从再分析数据推断出的周期变异性。