AGS-PRF: Wave-mean Flow Interactions in a Moist and Warmer Atmosphere

中纬度地区的天气系统，如气旋和沿沿着移动的高压系统，即使没有云和降水也可能存在。这些单独的气旋和高压系统不仅仅是被动地沿着沿着西风急流绕着地球仪盘旋。相反，它们在确定中纬度西风急流的时间平均强度以及它的平均纬度位置和跨度方面起着重要的作用。急流与沿其沿着移动的天气系统之间的相互作用在文献中被称为“波-平均流相互作用”。然而，水文循环是大气环流的一个组成部分。除了它的副产品，降雨，为所有人类使用和生态系统提供主要水源，水文循环有助于通过蒸发冷却热带海洋表面，并使极地地区比仅仅考虑通过向极地潜热传输获得的太阳能要温暖得多。本项目探讨了与单个风暴产生的降雨相关的潜热释放如何共同对中纬度西风急流的时间平均强度及其时空变化做出贡献。气候变暖时，水文循环的加强将如何改变中纬度西风急流的强度、平均纬度位置和跨度。PI在他的论文研究中开发了一种新的诊断工具，用于研究湿波-平均流相互作用。在这里，他使用这个新开发的工具来诊断湿波-平均流相互作用，并使用观测数据和大气环流模式输出将它们与对应物进行对比，而不考虑潜热释放。由于未来全球变暖预测的不确定性与未来水文循环强度的预测高度相关，更好地了解湿波平均相互作用的基本动态可能有助于减少全球变暖预测的不确定性。此外，该项目还支持一名刚开始科学生涯的博士后研究员，从而为该领域未来的科学工作者提供支持。

Weather systems in middle latitudes, such as cyclones and high pressure systems that move along jet streams, could still exist even without clouds and precipitation. These individual cyclones and high pressure systems do not just passively loop along westerly jet streams that meander around the globe. Instead they play important roles in determining the time mean intensity of the mid-latitude westerly jet stream as well as its mean latitudinal position and span. The interplay between the jet stream and weather systems that move along it is referred to as "wave-mean flow interaction" in the literature. Nevertheless, the hydrological cycle is an integral component of atmospheric circulations. Besides its by-product, rainfall, that provides the main source of water for all human uses and ecosystems, the hydrological cycle helps to cool tropical ocean surface via evaporation and keep Polar Regions much warmer than what would be by just considering the solar energy available there via poleward latent heat transport. This project explores how latent heat release associated with rainfall produced by individual storms also contributes collectively to the time mean intensity of mid-latitude westerly jet, as well as its temporal and spatial variations. It also concerns how the strengthening of hydrological cycle in a warmer climate would alter the intensity, mean latitudinal position and span of mid-latitude westerly jet. The PI developed a new diagnostic tool for studying moist wave-mean flow interactions in his dissertation research. Here he uses this newly developed tool to diagnose moist wave-mean flow interactions and contract them against the counterparts without considering latent heat release using both observational data and atmospheric general circulation model outputs.Since the future global warming projection uncertainties are highly related to future projections of hydrological cycle strength, a better understanding of the underlying dynamics of moist wave-mean interactions may help to reduce the global warming projection uncertainties. In addition, the project supports a postdoctoral researcher who is at the beginning of his scientific career, thereby providing for the future scientific workforce in this area.