The Jet Streams in a Warming World: Incorporating Moisture into Our Understanding of Midlatitude Circulation Change

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The jet streams are belts of westerly winds in the extratropics of both the Northern and Southern Hemispheres. They steer storm tracks across the United States, Europe, and Asia, as well as Australia, New Zealand, and South America and play a critical role in precipitation and extreme weather in the mid-latitudes. This research explores the response of the jet streams and storm tracks to slow variations of ocean surface temperatures and radiative forcing at the top of the atmosphere due to greenhouse gas emissions as well as volcanic aerosols by major eruptions. The position and intensity of the mid-latitude storm tracks affect precipitation and extreme weather for a substantial fraction of the world's population. This project will develop strategies to validate and improve weather and climate forecast prediction systems. Policy makers, industry stakeholders, and the public rely on model forecasts of storm tracks, and of potential trends in the future, to make informed decisions. The research will also support the education and training of three graduate students. It will provide them the opportunity to develop a physical understanding of the atmospheric circulation, computer-based modeling of weather and climate, and experience with high performance scientific computing.Climate models generally predict a poleward shift in the jet streams in response to global warming, but there is considerable uncertainty in the amplitude and structure of jet stream changes. This project will contrast established mechanisms that rely primarily on dry dynamical theory by exploring the role of moisture, which is a significant source of uncertainty for predicting jet streams. As warmer air can hold more moisture, it is expected that the atmosphere will be more strongly influenced by moist processes in the future.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.