Searching for Upper Atmospheric Waves at the Edge of Space (SURGE)

大气模拟正在进入一个从地面延伸到空间的全大气模式的新时代。这些模式将提供重大的社会效益，改进地面和空间天气预报以及对各种过程的预报，包括长期地表气候变化、卫星轨道阻力和全球导航卫星系统和无线电干扰。然而，这些新模式目前无法模拟中高层大气的基本环流。这极大地抑制了它们将这些层耦合在一起并将大气模拟为一个整体的能力。例如，在一个领先的气候模型中，极地中层和较低热层(80-110公里)的风速不仅是错误的，而且与观测结果相比，它们有半年是朝着错误的方向吹的。这一问题普遍存在，影响到几乎所有垂直延伸的大气模式，包括气象局扩展统一模式(Exum)，并成为实现全大气模式愿景的主要障碍。这种偏差的产生是因为几乎所有的全球模型对大气环流的一个基本组成部分：大气重力波(GWS)的表示都不准确。大气GWS在整个大气中输送能量和动量，并负责推动中层大气中的许多大尺度环流。更重要的是，对于中上层大气，这些模型完全没有次要重力波(2GW)的表示，次要重力波是在初级GW破裂时产生的，就像海浪撞击海滩一样。这些2GW的级联可以以非常不同的方式将动量输送到产生它们的主要GW，最近的理论工作表明，这些波对于实现中高层大气的真实环流是必不可少的。因此，迫切需要在全球中上层大气中观测、测量和理解2GW，以便它们能够在下一代全大气气候模式中得到体现，并实现从地表到空间边缘的现实大气预报。在浪涌中，我将使用一套复杂的全球观测和最先进的模型来探测、测量和模拟整个中高层大气中的2GW，并测试它们如何在下一代全大气模型中表示。这将填补对实现从地面到太空的准确大气预报至关重要的基本知识鸿沟。

Atmospheric modelling is entering a new era of whole-atmosphere models which extend from the surface to space. These models will provide significant societal benefit, improving both terrestrial and space-weather predictions and forecasts of processes as diverse as long-term surface climate change, satellite orbital drag and GNSS & radio disruptions. However, these new models currently fail to simulate fundamental circulations of the middle and upper atmosphere. This dramatically inhibits their ability to couple these layers together and simulate the atmosphere as one. For example, in one leading climate model, the winds in polar mesosphere and lower thermosphere (between 80-110km) are not only the wrong speed, but they blow in the wrong direction for half the year compared to observations. This problem is widespread, affecting nearly all vertically-extended atmospheric models including the Met Office Extended Unified Model (ExUM), and is as a major impediment to realising the vision of whole-atmospheric modelling. This bias occurs because nearly all global models have inaccurate representations of a fundamental component of the atmospheric circulation: atmospheric gravity waves (GWs). Atmospheric GWs transport energy and momentum throughout the atmosphere and are responsible for driving many large scale circulations in the middle atmosphere. More importantly for the middle and upper atmosphere, these models have no representation at all of secondary gravity waves (2GWs), which are generated when primary GWs break, like ocean waves crashing on a beach. These cascades of 2GWs can transport momentum in very different ways to the primary GWs that generated them, and recent theoretical work has shown that these waves are essential to achieving realistic circulations in the middle and upper atmosphere. There is therefore a critical needs to observe, measure and understand 2GWs throughout the middle and upper atmosphere globally, such that they can be represented in the next generation of whole-atmosphere climate models and achieve realistic atmospheric forecasts from the surface to the edge of space. In SURGE, I will use a sophisticated suite of global observations and state-of-the-art models to detect, measure and simulate 2GWs throughout the middle and upper atmosphere and test how they can be represented in next generation whole-atmosphere models. This will complete the fundamental knowledge gap crucial for realising accurate atmospheric forecasts from the surface to space.