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

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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.