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

中纬度的天气系统，如沿着急流移动的气旋和高压系统，即使没有云和降水，也可能仍然存在。这些单独的气旋和高压系统并不只是被动地沿着蜿蜒在全球各地的西风急流循环。相反，它们在确定中纬度西风急流的时间平均强度及其平均纬度位置和跨度方面起着重要作用。急流和沿其移动的天气系统之间的相互作用在文献中被称为“波-均流相互作用”。然而，水循环是大气环流的一个组成部分。除了为所有人类用途和生态系统提供主要水源的副产品降雨外，水循环还有助于通过蒸发来冷却热带海洋表面，并使极地地区保持温暖，而不是仅仅考虑那里通过向极地输送潜热可获得的太阳能。该项目探讨了与个别风暴产生的降水有关的潜热释放如何对中纬度西风急流的时间平均强度及其时空变化做出集体贡献。气候变暖，水文循环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。在他的论文研究中，PI为研究湿波-均流相互作用开发了一种新的诊断工具。在这里，他使用这个新开发的工具来诊断潮湿的波-平均流相互作用，并使用观测数据和大气环流模式输出来比较它们，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，更好地理解湿波-平均相互作用的潜在动力学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其科学生涯的博士后研究人员，从而为这一领域未来的科学队伍做好准备。

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.