中层平流层环流变化中大尺度模态的再探讨
A Revisit of Large-Scale Patterns in Middle Stratospheric Circulation Variations
AI总结：
本文应用本征微态方法分析1980-2022年ERA5平流层纬向风，识别出QBO及南北极环流模态，发现南极模态存在11年太阳周期信号，并构建了能预测南极极涡的线性模型。
摘要：
平流层大气环流的变化显著影响对流层天气和气候，理解这些变化可为平流层飞行器的研发与运行提供指导。尽管经过一个世纪的进展，由于平流层的复杂性，其环流中的大尺度模态仍未被充分理解。为解决这一问题，我们应用本征微态方法（EMA）分析了1980-2022年间ERA5再分析资料中70-10 hPa的纬向风。我们重点关注前三个主要模态，它们分别对应于准两年振荡（QBO）以及北极和南极的平流层环流。在去除高频分量后，我们观察到南极平流层环流模态存在显著的11年周期，这可能与太阳活动周期有关。相比之下，北极模态表现出5-6年的周期，而没有11年的周期性。这一差异可能源于极涡破裂的季节性时机：南极极涡持续到晚春和夏季，使其对太阳辐射更为敏感，而北极极涡在冬季和早春达到峰值。第四模态表现出南半球偶极子的特征，并与南极模态显著相关，领先约两个月。最后，我们开发了一个线性预测模型，该模型展示了对南极极涡的预测能力。
英文摘要：
Variations in stratospheric atmospheric circulation significantly influence tropospheric weather and climate, and understanding these variations can guide stratospheric aircraft development and operations. Despite a century of progress, large-scale patterns in stratospheric circulation remain poorly understood due to the stratosphere's complex nature. To address this, we applied the eigen microstate approach (EMA) to analyze zonal wind from 70-10 hPa using ERA5 reanalysis data from 1980-2022. We focused on the three leading modes, corresponding to the quasi-biennial oscillation (QBO) and stratospheric circulation in the Arctic and Antarctic. After removing high-frequency components, we observed a significant 11-year cycle in the Antarctic stratospheric circulation mode, possibly linked to the solar cycle. In contrast, the Arctic mode showed a 5-6-year cycle without 11-year periodicity. This difference likely arises from the seasonal timing of polar vortex breakdowns: the Antarctic vortex persists into late spring and summer, making it more sensitive to solar radiation, while the Arctic vortex peaks in winter and early spring. The fourth mode showed features of a Southern Hemisphere dipole and was significantly correlated with the Antarctic mode, leading it by about two months. Finally, we developed a linear prediction model that demonstrated predictive skill for the Antarctic polar vortex.
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