How Will Global Warming Change the Storm Tracks? Investigating the Importance of Diabatic Processes using High-resolution Simulations

预计未来几十年，随着气候变暖，热带气旋的路径和强度将发生变化，尽管这些变化的幅度甚至迹象仍然不确定。较弱的对流层温度对比和增强的比湿度的潜在竞争效应，由于对流层预期加深、对流层上部斜压性增强和全球环流改变的不确定影响而进一步复杂化，导致预测对流层外气旋和风暴路径变化的不确定性很大，反过来，对单个风暴动力学的研究表明，通过非绝热产生的低层位涡释放潜热，对风暴的发展以及产生破坏性的大风和暴雨至关重要。这些动态在温暖潮湿的大气中应该更加活跃，但相关特征的尺度低于全球气候模式的分辨率空间尺度。该项目将检验以下假设：个别风暴和风暴路径，包括其具有气候重要性的热量和水分向极地输送，对模式分辨率敏感，而且这种敏感性在较温暖的气候中更高。将执行一个高分辨率模式模拟当前和气候变化条件下北大西洋风暴路径的方案，以便在区域和全球配置中使用天气研究和预报模式来检验这一假设。该项目的智力价值在于系统地探索风暴中的非绝热效应与全球气候系统之间的双向相互作用。热带风暴和风暴路径的变化通过影响水的供应以及破坏性的风、洪水和巨浪的风险，对社会产生潜在的重要影响。对这些变化的更可靠预测以及对其相关不确定性的更好理解是本研究的潜在社会效益和本项目的更广泛影响。其他更广泛的影响包括对研究生和本科生研究人员的指导，基于项目结果的教育和推广，以及在气候应用中使用WRF模型对更广泛的气候研究界的价值。

It is expected that the tracks and intensities of extratropical cyclones will change over coming decades as climate warms, though the magnitudes and even the signs of these changes remain uncertain. The potentially competing effects of weaker lower-tropospheric temperature contrasts and enhanced specific humidity, further complicated by the uncertain influences of an expected deepening of the troposphere, stronger baroclinicity in the upper troposphere, and an altered global circulation, lead to great uncertainty in projecting changes in extratropical cyclones and stormtracks and, in turn, in projecting how their roles in Earth's climate system will change.Studies of the dynamics of individual storms reveal that the release of latent heat, through the diabatic production of low-level potential vorticity, is critical for storm development and for producing damaging winds and flooding rains. These dynamics should be more vigorous in a warmer and moister atmosphere, but the scales of the relevant features fall below the resolved spatial scales of global climate models. This project will test the hypothesis that individual storms and the stormtracks, including their climatically important poleward transports of heat and moisture, are sensitive to model resolution, and that this sensitivity is greater in a warmer climate. A program of high-resolution model simulations of the North Atlantic stormtrack under current day and climate-change conditions will be carried out to test this hypothesis using the Weather Research and Forecasting (WRF) model, in regional and global configurations. The intellectual merit of this project is in systematically exploring the two-way interactions between diabatic effects in storms and the global climate system. Changes in extratropical storms and stormtracks have potentially important impacts on society, through their effects on the availability of water and on the risks of damaging winds, flooding rains, and high waves. More reliable projections of these changes and improved understanding of their associated uncertainties are a potential societal benefit from this research and a broader impact of this project. Additional broader impacts include the mentoring of graduate and undergraduate researchers, education and outreach based on project results, and the value, to the broader climate research community, of using the WRF model in climate applications.