太平洋与大西洋如何协同调节美国东南部降水变率？
How do the Pacific and Atlantic Oceans synergize to modulate Southeastern United States Precipitation Variability?
AI总结：
本研究通过条件天气形势分析，揭示了高层大气遥相关与低层北大西洋副热带高压的相互作用如何协同调节美国东南部降水的异常变率。
摘要：
本研究探讨了美国东南部（SEUS）异常正负降水事件背后的机制，强调了高层大尺度大气遥相关与低层北大西洋副热带高压（NASH）之间的相互作用。通过对太平洋-北美-大西洋区域高低层位势高度进行新颖的条件天气形势分析，我们识别出代表源自太平洋和大西洋的持续性与反复性环流模式的独特聚类。我们对低层条件天气形势的分析揭示了影响SEUS地区降水模式的NASH两个不同相位。在一个相位中，NASH北部边界的减弱和东移减少了中心低空急流，增强了气旋式环流，并增加了SEUS的降水。在另一个相位中，与SEUS降水增加相关的过度潜热加热触发了波列模式，从而增强了NASH的强度。相反，在异常负降水事件期间则出现相反的条件。此外，高层条件天气形势表明，东亚夏季季风的大尺度动力学触发了Rossby波模式，从高层对SEUS降水变率做出了相当大的贡献。因此，我们的研究突出了高低层全球大气遥相关在塑造SEUS降水模式中的关键作用。
英文摘要：
This study explores the mechanisms behind anomalous positive and negative rainfall events in the southeastern United States (SEUS), emphasizing the interplay between upper-level large-scale atmospheric teleconnections and the lower-level North Atlantic Subtropical High (NASH). Through a novel conditional weather regime analysis of geopotential height at both lower and upper levels across the Pacific-North America-Atlantic region, we identify distinct clusters representing persistent and recurring circulation patterns originating from the Pacific and Atlantic Oceans. Our analysis of lower-level conditional weather regimes reveals two distinct phases of the NASH that influence rainfall patterns in the SEUS region. In one phase, the weakening and eastward shift of the NASH's northern boundary reduces the central low-level jet, enhances cyclonic circulation, and increases rainfall in the SEUS. In the other phase, the excessive latent heating associated with enhanced SEUS rainfall triggers a wave train pattern that strengthens the intensity of NASH. Conversely, the opposite conditions apply during anomalous negative rainfall events. Additionally, the upper-level conditional weather regime indicates that large-scale dynamics of East Asian summer monsoons trigger the Rossby wave patterns, contributing considerably to the variability in SEUS rainfall from the upper levels. Therefore, our research highlights the crucial role of global atmospheric teleconnections at upper and lower levels in shaping SEUS precipitation patterns.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
