Planetary and Gravity Waves as Drivers of Sudden Stratospheric Warmings (PEGASUS)

行星波和重力波是平流层突然变暖的驱动因素（PEGASUS）

• 批准号: NE/S00985X/1
• 负责人: Corwin Wright
• 金额: $ 80.62万
• 依托单位: University of Bath
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FS00985X%2F1
• 关键词: Planetary; Gravity; Waves; Drivers; Sudden

Sudden stratospheric warmings (SSWs) are some of the most dramatic events in the entire atmosphere. Over just a few days, the high-altitude jet stream stops and sometimes even reverses, and polar stratospheric temperatures can shoot up as much as 50 degrees Celsius. Their effects propagate upwards, where they modulate the near-Earth space environment of the ionosphere, and downwards, where they can cause extreme winter weather in densely-populated regions such as Europe and North America.SSWs occur on average twice every three winters, but may occur several times in one winter and then not at all for several years afterwards. Forecasting them more than a few days in advance is extremely challenging. Their effects are also very difficult to predict - while (for example) the 'Beast From The East' of February 2018 in Europe and the 'Polar Vortex Winter' of January 2014 in the eastern United States were directly attributable to SSWs which happened a few days earlier, many SSWs have occurred with almost no effect on surface weather.In PEGASUS, we will use new satellite measurement techniques and advanced computer models to better understand the physics of how SSWs develop, and of how and why they affect both surface weather and space weather. We will (i) test a recent theory that changes our understanding of how and why SSWs happen, (ii) investigate the details of how, when and where SSWs affect surface weather and (iii) measure the effects of SSWs on the global upper atmosphere, with implications for GPS and radio communications.(i) Traditionally, we thought that SSWs were triggered by extremely large and unusually intense 'planetary waves' travelling through the atmosphere. These large waves seriously disrupt the jet stream, making it collapse and triggering an SSW. However, recent work has shown that this conceptual model does not properly explain the observed SSW record. Instead, a new theory challenges this model at a fundamental level. This new theory is that smaller-scale 'gravity waves' over the weeks before the SSW nudge the jet stream into a less robust state, weak enough that normal winter weather can be enough to trigger the start of an SSW. The precise distribution of these gravity waves, in space, time and intensity, may also affect how severe the surface effects of the SSW are. There is thus an important need to test this new theory. PEGASUS will do so. We will use advanced new satellite methods of measuring both the large planetary waves and the much smaller gravity waves to study the development of every SSW in the last sixteen years. We will also study idealised mathematical models (i.e. models which strip away unnecessary details) to understand the underlying physics and mathematics of how SSWs evolve and develop. This will provide a robust and critical test of the new theory.(ii) This combination of observational and theoretical insight will let us test and assess how well forty leading climate models reproduce SSWs. We will use this information to select the best such models, tested against both observations and theory from (i). We will then study these selected models in close detail to understand what features of SSWs cause them to affect the surface and the upper atmosphere, with the aim of better predicting both SSW development and surface effects in future. In particular, we will closely study the differences between the surface effects of two different types of SSW, known as 'splits' and 'displacements' based on how they affect the jet stream.(iii) Finally, we will quantify how SSWs affect global GPS signals and radio communications, allowing us to understand not just the surface weather effects of SSWs but also their space-weather effects. This will use a chain of five state-of-the-art radars spanning from pole-to-pole, and global measurements of upper-atmospheric composition from satellite measurements.

平流层突然变暖（SSW）是整个大气中最引人注目的事件之一。在短短几天内，高空急流停止，有时甚至逆转，极地平流层温度可飙升至50摄氏度。它们的影响向上传播，调制电离层的近地空间环境，向下传播，在欧洲和北美等人口稠密地区造成极端冬季天气。SSW平均每三个冬天发生两次，但可能在一个冬天发生几次，然后在几年后根本没有发生。提前几天预测它们是非常具有挑战性的。它们的影响也很难预测，（例如，2018年2月欧洲的“东方野兽”和2014年1月美国东部的“极地涡旋冬季”可直接归因于几天前发生的SSW，许多SSW发生时几乎对地面天气没有影响。在PEGASUS，我们将使用新的卫星测量技术和先进的计算机模型，以更好地了解SSW如何发展的物理学，以及它们如何和为什么影响地面天气和空间天气。我们将（i）测试最近的理论，改变了我们的理解如何以及为什么SSW发生，（ii）调查SSW如何，何时以及在何处影响地面天气的细节和（iii）测量SSW对全球高层大气的影响，对GPS和无线电通信的影响。(i)传统上，我们认为SSW是由穿过大气层的非常大且异常强烈的“行星波”引发的。这些巨浪严重扰乱了急流，使其崩溃并触发SSW。然而，最近的工作表明，这个概念模型不能正确解释所观察到的SSW记录。相反，一个新的理论在根本层面上挑战了这个模型。这种新理论认为，在SSW之前的几周内，较小规模的“重力波”将急流推入一种不那么强劲的状态，弱到足以使正常的冬季天气足以触发SSW的开始。这些重力波在空间、时间和强度上的精确分布也可能影响SSW表面效应的严重程度。因此，迫切需要检验这一新理论。飞马会这么做的。我们将使用先进的新卫星方法来测量大的行星波和小得多的重力波，以研究过去16年来每一个SSW的发展。我们还将研究理想化的数学模型（即剥离不必要细节的模型），以了解SSW如何演变和发展的基本物理和数学。这将为新理论提供一个强有力的和关键的测试。(ii)这种观测和理论洞察力的结合将使我们能够测试和评估四十个领先的气候模型再现SSW的效果。我们将使用这些信息来选择最好的模型，并根据（i）中的观察和理论进行测试。然后，我们将仔细研究这些选定的模型，以了解SSW的特征导致它们影响地面和高层大气，目的是更好地预测SSW的发展和未来的地面效应。特别是，我们将仔细研究两种不同类型的SSW，被称为“分裂”和“位移”的基础上，他们如何影响射流的表面效果之间的差异。(iii)最后，我们将量化SSW如何影响全球GPS信号和无线电通信，使我们不仅能够了解SSW的表面天气效应，还可以了解它们的空间天气效应。这将使用一系列五个最先进的雷达，从极点到极点，并通过卫星测量对高层大气成分进行全球测量。

项目成果

Interannual variability of the 12-hour tide in the mesosphere and lower thermosphere in 15 years of meteor-radar observations above Rothera (68°S, 68°W)

罗瑟拉上空 15 年流星雷达观测中中层和低热层 12 小时潮汐的年际变化（68

• DOI: 10.1002/essoar.10510647.1
• 发表时间: 2022
• 作者: Dempsey S

Aeolus wind lidar observations of the 2019/2020 Quasi-Biennial Oscillation disruption with comparison to radiosondes and reanalysis

风神激光雷达对 2019/2020 年准两年期振荡中断的观测与无线电探空仪的比较和再分析

• DOI: 10.5194/egusphere-2023-285
• 发表时间: 2023
• 作者: Banyard T

Observations of Typhoon Generated Gravity Waves From the CIPS and AIRS Instruments and Comparison to the High-Resolution ECMWF Model

利用 CIPS 和 AIRS 仪器观测台风产生的重力波并与高分辨率 ECMWF 模型进行比较

• DOI: 10.1029/2022jd038170
• 发表时间: 2023
• 期刊: Atmospheres
• 作者: Cullens C

Martian Gravity Waves Observed by the Thermal Emission Imaging System (THEMIS) During Northern Summer

热发射成像系统（THEMIS）在北半球夏季观测到的火星重力波

• DOI: 10.1029/2022je007653
• 发表时间: 2023
• 期刊: Planets
• 作者: Battalio J

Atmospheric Gravity Waves: Processes and Parameterization

大气重力波：过程和参数化

• DOI: 10.1175/jas-d-23-0210.1
• 发表时间: 2023
• 期刊: Journal of the Atmospheric Sciences
• 影响因子: 3.1
• 作者: Achatz U