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

急流是北半球和南半球温带地区的西风带。 它们引导风暴路径穿越美国、欧洲、亚洲以及澳大利亚、新西兰和南美洲，并在中纬度地区的降水和极端天气中发挥着关键作用。 这项研究探讨了急流和风暴路径对海洋表面温度缓慢变化的响应，以及由于温室气体排放和火山喷发产生的火山气溶胶而导致的大气顶部辐射强迫的响应。 中纬度风暴路径的位置和强度影响着世界上很大一部分人口的降水和极端天气。该项目将制定验证和改进天气和气候预报系统的策略。 政策制定者、行业利益相关者和公众依靠风暴路径和未来潜在趋势的模型预测来做出明智的决策。 该研究还将支持三名研究生的教育和培训。它将为他们提供对大气环流的物理理解、基于计算机的天气和气候建模以及高性能科学计算经验的机会。气候模型通常预测急流因全球变暖而向极地移动，但急流变化的幅度和结构存在相当大的不确定性。 该项目将通过探索水分的作用来对比主要依赖于干动力学理论的现有机制，水分是预测急流的不确定性的重要来源。 由于温暖的空气可以容纳更多的水分，预计未来大气将受到潮湿过程的更强烈影响。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.