Collaborative Research: Structure and Influence of Coherent Vertical Pulses of Wave Activity Flux in Observations and Models, from Daily to Seasonal Timescales

平流层是位于地表上方约8-10公里的一个大气层，它可以通过与下方对流层的相互作用影响北半球的冬季天气。这些相互作用可能需要几周的时间来发展和成熟，并可能提前两到六周提供有关天气模式变化的信息，特别是在秋季和冬季。其中一些相互作用的一个重要起点是欧亚大陆北部对流层风的变化，这种变化发生在相对较短的时间内，通常不到两周。这种风的变化与“波浪活动通量的垂直脉冲”有关，它可以影响极地平流层，并最终影响地面天气。本研究旨在全面了解这些短期“脉冲事件”及其对半球的影响，方法是研究这些事件的空间结构和时间演变，并研究它们在启动较慢的对流层-平流层相互作用中的作用，这种相互作用最终导致远离脉冲的地区（包括北美、欧洲和亚洲部分地区）的天气变化。这一改进的认识也将提供一种潜力评估，以便在预测天气变化的某些方面时考虑到这些脉冲事件，可提前数周。将利用观测数据来研究这些事件，以检查其结构和调查其潜在的物理机制，并利用天气预报模型的输出来评估模型在多大程度上能够真实地再现这些事件及其影响。这项调查将使人们更好地了解对流层和平流层如何相互作用以及冬季天气变化的原因之一。该项目还将教育和培训研究生，包括通过开发教学门户、学生通过社交媒体展示教程以及提供实验预测等方式进行公共宣传和教育。

The stratosphere, an atmospheric layer about 8-10 km above the surface, can influence winter weather over the Northern Hemisphere via its interactions with the troposphere beneath. These interactions can take several weeks to develop and mature, and may provide information about changes to weather patterns two to six weeks in advance, particularly during the fall and winter. An important starting point for some of these interactions is a change in the tropospheric winds over Northern Eurasia that occurs over a relatively short period, generally less than two weeks. This change in winds is associated with the "vertical pulses of wave activity flux", which can influence the polar stratosphere and, eventually, surface weather. This research aims to provide a comprehensive understanding of these short-term "pulse events" and their hemispheric influence by examining the spatial structure and temporal evolution of the events and investigating their role in the initiation of slower troposphere-stratosphere interactions that end up resulting in changes to weather over regions remote from the pulses, including over parts of North America, Europe, and Asia. This improved understanding will also provide an evaluation of the potential for considering these pulse events in the prediction of some aspects of weather variability up to several weeks in advance. The events will be studied using observational data for examining their structure and investigating their underlying physical mechanisms, and also using the output of weather forecast models to assess how realistically models are able to reproduce these events and their influence. This investigation will provide a better understanding of how the troposphere and stratosphere interact and of one of the causes of variations in winter weather. The project will also educate and train graduate students and include public outreach and education through development of a teaching portal, student presentation of tutorials through social media, and provision of an experimental forecast.