We investigate 21st-century hydroclimate changes over the United States (US) during winter and the sources of projection uncertainty under three emission scenarios (SSP2–4.5, SSP3–7.0, and SSP5–8.5) using CMIP6 models. Our study reveals a robust intensification of winter precipitation across the US, except in the Southern Great Plains, where changes are very small. By the end of the 21st century, winter precipitation is projected to increase by about 2–5% K⁻¹ over most of the US. The frequency of very wet winters is also expected to increase, with 6–7 out of 30 winters exceeding the very wet threshold under the different scenarios. Our results suggest that the enhancement of future winter precipitation is modulated largely by coupled dynamic and thermodynamic responses, though partly offset by thermodynamic responses. Overall, our results highlight a high likelihood of increasing impacts from winter precipitation due to climate change.

我们使用 CMIP6 模型研究了美国 (US) 冬季 21 世纪水文气候变化以及三种排放情景（SSP2–4.5、SSP3–7.0 和 SSP5–8.5）下的预测不确定性来源。我们的研究表明，美国各地冬季降水大幅增加，但南部大平原除外，那里的变化非常小。到 21 世纪末，美国大部分地区的冬季降水量预计将增加约 2-5% K ^-1 。预计非常潮湿冬季的频率也会增加，在不同情景下，每 30 个冬季中有 6-7 个冬季会超过非常潮湿的阈值。我们的结果表明，未来冬季降水的增加很大程度上是由动力和热力学响应耦合调节的，尽管热力学响应部分抵消了这一影响。总体而言，我们的结果凸显了气候变化导致冬季降水的影响很有可能增加。