Far-flung influences on midlatitude climate and weather extremes: The stratospheric pathway

遥相关是将地球不同地区之间的天气和气候变化联系起来的过程，通常相隔数千公里。它们对于在未来数周到数十年的区域尺度上做出可靠的天气和气候预测非常重要，尤其是在数十亿人居住的中纬度地区。最近有很多推测认为，尽管平流层空气稀薄，海拔高，但它可能在这些遥相关中起着重要作用。更具体地说，热带和北极的气候变率都可能影响平流层极地涡旋，这是一个海拔10公里以上的强风区域，环绕冬季极点。在极端情况下，这个涡旋可能会在被称为平流层突然变暖的戏剧性事件中暂时破裂，其影响向下传播到地球表面（参见这个解释性视频：https://youtu.be/VnlFFaF_l7I）.There)对于这种潜在的“平流层路径”背后的机制仍然有很多需要了解的。开放的研究问题包括，但不限于，热带和极地影响如何相互作用，这些远程影响如何影响平流层极地涡旋的三维结构（如上所示），平流层信号如何传达到地面，以及它们如何影响极端天气的风险。该项目将使用尖端的计算和数据分析工具来解决这些重要问题。项目目标和方法：该学生将有机会加入一个关于北极远程连接的重大新合作项目，该项目还包括布里斯托尔大学、牛津大学、雷丁大学、班戈大学、南安普敦大学和国家海洋学中心的科学家。这将使他们有机会建立更广泛的合作者网络，并在定期项目会议上讨论和展示结果。为了在这个重要的研究领域取得进展，学生将使用我们小组最近开发的Isca气候建模框架（https://execlim.github.io/IscaWebsite/index.html）。Isca是一种相对简单和独特灵活的模型，可用于模拟不同复杂程度的大气，因此是探索基本机制的理想选择。从这些实验中获得的知识将用于分析观测到的气候记录，最先进的“大集合”气候预测，以及英国气象局合作者的季节到十年预测。在导师的支持下，鼓励候选人根据自己的兴趣塑造研究重点。

Teleconnections are processes which link variations in weather and climate between different parts of the globe, often many thousands of kilometres apart. They are important for making reliable predictions of weather and climate at the regional scale, from weeks to decades ahead, particularly in the midlatitudes where billions of people live. Recently there has been much speculation that the stratosphere may play a significant role in these teleconnections, despite its thin air and high altitude.More specifically, climate variability in both the tropics and the Arctic may influence the stratospheric polar vortex, a region of intense winds at above 10 km in altitude, encircling the winter pole. In extreme cases, this vortex may temporarily break down in dramatic events known as sudden stratospheric warmings, with impacts propagating downwards to the Earth's surface (see this explainer video: https://youtu.be/VnlFFaF_l7I).There is still much to be understood about the mechanisms underlying this potential 'stratospheric pathway'. Open research questions include, but are not limited to, how tropical and polar influences interact, how these remote influences affect the 3D structure of the stratospheric polar vortex (as illustrated above), how stratospheric signals are communicated down to the surface, and how they impact the risk of extreme weather. This project will use cutting-edge computational and data analysis tools to tackle these important problems.Project Aims and Methods:The student will have the opportunity to join a major new collaboration on Arctic teleconnections which also includes scientists at the Universities of Bristol, Oxford, Reading, Bangor, Southampton, and the National Oceanography Centre. This will give them the opportunity to build a wider network of collaborators, and to discuss and present results at regular project meetings. To make progress in this significant research area, the student will use the Isca climate modelling framework, recently developed within our group (https://execlim.github.io/IscaWebsite/index.html). Isca is a relatively simple and uniquely flexible model that can be used for simulating the atmosphere at varying levels of complexity and is therefore ideal for probing fundamental mechanisms. Knowledge gained from these experiments will be applied to the analysis of observed climate records, state-of-the-art 'large ensemble' climate projections, as well as seasonal-to-decadal predictions from collaborators at the UK Met Office. With support from the supervisors, the candidate will be encouraged to shape the focus of research to suit their interests.