DRAGON-WEX: The DRake pAssaGe sOuthern oceaN Wave EXperiment

DRAGON-WEX：德雷克海峡南海波浪实验

• 批准号: NE/R001235/1
• 负责人: Tracy Moffat-Griffin
• 金额: $ 14.44万
• 依托单位: British Antarctic Survey
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FR001235%2F1
• 关键词: DRAGON; WEX; DRake; pAssaGe; sOuthern

Gravity waves are atmospheric waves that can be generated by winds blowing over mountains, storms, unstable jet streams and strong convection. As the waves ascend from their sources in the lower atmosphere, into the stratosphere and mesosphere, they transport momentum in a "momentum flux". When the waves become unstable they "break", rather like ocean surface waves breaking on a beach. This acts to transfer their momentum into the atmosphere, exerting a "drag force" that dramatically influences the global atmospheric circulation.Computer General Circulation Models (GCMs) used for numerical weather prediction and climate research must represent these waves realistically if they are to predict the behaviour of the real atmosphere.However, the GCMs display "biases" in which the behaviour they predict does not match that revealed by observations. The largest biases in nearly all GCMs occur in the winter and springtime Antarctic stratosphere. There, they produce a polar region, the "polar vortex", that when compared to observations, is too cold by 5-10 K, has winds that are too strong by about 10 m/s and that persists some 2-3 weeks too long into spring before it breaks up. These significant biases are known as the "cold pole" problem.It is now realised that the biases arise because the GCMs are missing large amounts of gravity-wave flux that must occur in the real atmosphere at latitudes near 60 degrees S. These latitudes include the stormy Southern Ocean and the Drake Passage. However, the nature, sources, variability and fluxes of these "missing" waves are currently very uncertain. In DRAGON-WEX (DRake pAssaGe sOuthern oceaN - Wave EXperiment) we will use satellites, radiosondes and radars to directly measure the waves over the Southern Ocean and Drake Passage near 60 S, determine their properties and investigate their role in coupling together the troposphere, stratosphere and mesosphere. Our results will thus help resolve the cold pole problem.We will apply a very powerful novel 3D method we have developed for analysing satellite data. With our method, we can detect individual gravity waves in the stratosphere in 3D and measure their momentum fluxes. Importantly, because it is a fully 3D method we can do this without the needing the assumptions that critically limit earlier 1D and 2D methods. We will use our method to identify an estimated 100,000 individual gravity waves near 60 S.We will combine the satellite observations with measurements of gravity waves made by radiosondes ("weather balloons") and radars to characterise the "missing" gravity waves, determining their short-term and seasonal variability and investigate their sources - in particular, the contributions made to the waves by the mountains of the Southern Andes and Antarctic Peninsula, storms over the Southern Ocean/Drake Passage, unstable jet streams and by waves propagating into the 60 S region from latitudes to the North or South.We will use a unique combination of meteor radars, one in the Antarctic and a new radar on the remote mountainous island of South Georgia to measure the winds, waves and tides of the mesosphere. We will determine the degree to which fluctuations in the waves we measure in the stratosphere drive the variability of the mesosphere and, in particular, the role of waves in driving anomalous events recently observed at heights near 90 km in the polar mesosphere, when the Northward winds of the general circulation appeared to briefly cease and when the occurrence frequency of polar mesospheric clouds was greatly reduced.We will use meteor radars on the island of South Georgia and at Rothera in the Antarctic to investigate recent suggestions that waves generated by mountains can propagate to heights of 90 km or more - effectively the edge of space.Finally, in Pathways to Impact we will work closely with the Met Office to use our results to test and improve their Unified Model GCM.

重力波是一种大气波，可以由吹过山脉的风、风暴、不稳定的急流和强对流产生。当波从它们在低层大气中的源上升到平流层和中间层时，它们以“动量通量”的方式传输动量。当波浪变得不稳定时，它们会“破碎”，就像海洋表面的波浪在海滩上破碎一样。这种作用将它们的动量转移到大气中，产生一种“拖曳力”，极大地影响全球大气环流。用于数值天气预报和气候研究的计算机大气环流模式（GCM）如果要预测真实的大气行为，就必须真实地代表这些波。然而，大气环流模型显示出“偏差”，即它们预测的行为与观测结果不符。几乎所有大气环流模式的最大偏差都发生在冬季和春季的南极平流层。在那里，它们产生了一个极地区域，即“极地涡旋”，与观测结果相比，它太冷了5-10 K，风速太强了约10 m/s，并且在春天之前持续了2-3周。这些显著的偏差被称为“冷极”问题，现在人们认识到，偏差的产生是因为大气环流模型遗漏了大量的重力波通量，而这些通量必须出现在南纬60度附近的真实的大气中。这些纬度包括多风暴的南大洋和德雷克海峡。然而，这些“消失”的波的性质、来源、可变性和通量目前非常不确定。在DRAGON-WEX（DRake pAssaGe sOujuoceaN- Wave Experiment）中，我们将使用卫星、无线电探空仪和雷达直接测量60 S附近南大洋和德雷克海峡上空的波浪，确定它们的特性，并研究它们在对流层、平流层和中间层耦合中的作用。因此，我们的研究结果将有助于解决冷极问题。我们将应用一个非常强大的新的3D方法，我们已经开发的卫星数据分析。利用我们的方法，我们可以在3D中检测平流层中的单个重力波并测量它们的动量通量。重要的是，因为它是一个完全的3D方法，我们可以做到这一点，而不需要严格限制早期的1D和2D方法的假设。我们将使用我们的方法来识别60 S附近的估计100，000个单独的重力波。我们将联合收割机与无线电探空仪对重力波的测量相结合（“气象气球”）和雷达来探测“失踪的”重力波，确定它们的短期和季节性变化，并调查它们的来源--特别是，南安第斯山脉和南极半岛的山脉、南大洋/德雷克海峡上的风暴、不稳定的急流以及从北纬或南纬传播到60 S区域的波浪对波浪的贡献。我们将使用流星雷达的独特组合，一个在南极，一个在南格鲁吉亚偏远的多山岛屿上的新雷达，用于测量中间层的风、浪和潮汐。我们将确定我们在平流层测量的波动驱动中间层变化的程度，特别是波在驱动最近在极地中间层90公里附近高度观察到的异常事件中的作用，当大气环流的北风似乎短暂停止，极地中层云出现的频率大大减少时，我们将使用流星在南格鲁吉亚岛和南极罗瑟拉岛的雷达上进行研究，以调查最近提出的由山脉产生的波可以传播到90公里或更高的高度--有效地传播到太空边缘的建议。最后，在“影响的途径”中，我们将与英国气象局密切合作，利用我们的结果来测试和改进他们的统一模型GCM。

项目成果

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

罗瑟拉 (68S, 68W) 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

• DOI: 10.1002/essoar.10510647.2
• 发表时间: 2022
• 作者: Dempsey S

Observations of gravity waves in the OH airglow layer above Rothera (68S, 68W) using a three-dimensional S-Transform analysis

使用三维 S 变换分析观测 Rothera（68S、68W）上方 OH 气辉层中的重力波

• DOI: 10.22541/essoar.167397443.32102383/v1
• 发表时间: 2023
• 作者: Dempsey S

Stratospheric gravity-waves over the mountainous island of South Georgia: testing a high-resolution dynamical model with 3-D satellite observations and radiosondes

• DOI: 10.5194/acp-2020-465
• 发表时间: 2020
• 作者: N. Hindley;C. Wright;A. Gadian;L. Hoffmann;J. Hughes;D. Jackson;J. King;N. Mitchell;T. Moffat‐Griffin;A. Moss;S. Vosper;A. Ross

Winds and tides of the Extended Unified Model in the mesosphere and lower thermosphere validated with meteor radar observations

通过流星雷达观测验证了中层和低热层扩展统一模型的风和潮汐

• DOI: 10.5194/angeo-39-487-2021
• 发表时间: 2021
• 期刊: Annales Geophysicae
• 影响因子: 1.9
• 作者: Griffith M

Interannual Variability of the 12-hr Tide in the Mesosphere and Lower Thermosphere in 15 Years of Meteor-Radar Observations Over Rothera (68°S, 68°W)

罗瑟拉 (68°S, 68°W) 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

• DOI: 10.1029/2022jd036694
• 发表时间: 2022
• 期刊: Atmospheres
• 作者: Dempsey S