Koushik N, Kumar K Kishore, Pramitha M
Space Physics Laboratory, Vikram Sarabhai Space Centre, Indian Space Research Organisation, Thiruvananthapuram, 695022, India.
Department of Physics and Astronomy, Clemson University, Clemson, SC, 29634, USA.
Sci Rep. 2022 Feb 21;12(1):2937. doi: 10.1038/s41598-022-06864-7.
Dramatic meteorological phenomena in the winter polar stratosphere known as Sudden Stratospheric Warming (SSW) events are well recognized for their impacts felt across the whole atmosphere. Apart from the influence of tropospheric forcing and stratospheric control, many studies have addressed the possible role of external factors on the occurrence of SSW events. Here, with the help of reanalysis datasets, we present a hitherto unexplored connection between the tropical upper stratosphere and the polar vortex. We identify enhanced planetary wave driving around the tropical stratopause and poleward progression of the zero-wind line as early indicators for the occurrence of SSW events. We demonstrate that the poleward progression of the zero wind line results in efficient focusing of planetary waves into the polar vortex which culminates in its disruption. Statistically, nearly 70% of the SSW events that took place so far have been preceded by enhanced tropical stratopause wave driving which points towards identifying this as a potential precursor for the occurrence of SSW events. After the year 2000, significantly a greater number of SSW events have been found to be preceded by enhanced tropical stratopause wave driving.
冬季极地平流层中被称为平流层突然增温（SSW）事件的剧烈气象现象，因其对整个大气的影响而广为人知。除了对流层强迫和平流层控制的影响外，许多研究探讨了外部因素在SSW事件发生中可能扮演的角色。在此，借助再分析数据集，我们揭示了热带高层平流层与极涡之间一种此前未被探索的联系。我们确定热带平流层顶周围增强的行星波驱动以及零风线向极地方向的推进是SSW事件发生的早期指标。我们证明零风线向极地方向的推进导致行星波有效地聚焦到极涡中，最终导致极涡破裂。从统计数据来看，到目前为止发生的近70%的SSW事件之前都有热带平流层顶波驱动增强的情况，这表明可将其视为SSW事件发生的一个潜在先兆。2000年之后，发现有明显更多的SSW事件之前存在热带平流层顶波驱动增强的情况。
