A global climatology of sting-jet cyclones

刺喷射气旋的全球气候学

• 批准号: NE/X010473/1
• 负责人: Suzanne Gray
• 金额: $ 9.96万
• 依托单位: University of Reading
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX010473%2F1
• 关键词: global; climatology; sting; jet; cyclones

Winter storms, formally called mid-latitude or extra-tropical cyclones, are a major natural hazard in the midlatitudes. They can cause as much damage as hurricanes, despite somewhat weaker winds, due to their long fronts that can trail for more than 1000 km. Damage can come from extreme wind, rain and storm surge, and storms with exceptionally strong winds are often called windstorms. Since 2015 the Met Office has named all storms impacting the UK that have the potential to cause an amber or red weather warning to improve the communication of impending potentially dangerous weather; typically about 7 named storms (and many more unnamed storms) occur each year. Sting jets have been identified in some of the most damaging mid-latitude cyclones that have affected the UK since their first identification in 2004 from a re-examination of observations of the 1987 Great October Storm. The damage caused by this storm is indicated by the reported insured loss of $6.3bn (indexed to 2012 values). Sting jets are coherent airflows that descend over a few hours from within the cloud head, a band of cloud that hooks poleward around the centre of intense cyclones. These jets are distinct from the other longer-lived, broader-scale and much better characterised near-surface wind jets. While their wind footprints are typically just 50-100 km across, they can lead to distinct regions of exceptionally strong near-surface winds, and damaging gusts. Our understanding of the dynamics of sting jets has advanced considerably since their first identification, but mostly through analysis of case studies of cyclones crossing the North Atlantic to affect northwest Europe. A single case of sting-jet activity originating in the Mediterranean has recently been published, but no published cases exist for other mid-latitude regions and published climatologies only cover the North Atlantic. Despite this, there are no known physical reasons why sting jets should not develop over other oceanic basins and the type of atmospheric instability associated with sting jets has been shown to be widespread over the mid-latitude oceans. This project will produce the first global climatology of sting-jet cyclones and characterise the differences between these cyclones and cyclones that do not contain sting jets. We will apply a sting-jet environmental precursor tool to cyclones identified and tracked in reanalysis data. Reanalysis data provide the most complete representation of past weather and climate and are generated by blending observations with weather forecasts rerun using a consistent modern weather forecast model. The transient, relatively small-scale nature of sting jets and the type of atmospheric instability associated with their generation mean that they can only be represented by models with very high resolution (i.e., the equations of motion are solved at points that are closely separated in space) which are typically limited in data period and/or regional in nature. The precursor tool is designed to diagnose environmental conditions conducive to sting jet formation in multi-decadal, global datasets, such as reanalyses, that have too coarse resolution to represent sting jets.This work will exploit previous work by members of the project team to develop the precursor and, more recently, improve its computational efficiency as part of work to implement it at the Met Office as a forecast tool (it is applied to forecast output in real time), as well as the availability of cyclone tracks derived from the latest ECMWF reanalysis, ERA5 (which is available from 1979 to the present day). These innovations mean that a global climatology is now feasible. The resulting climatology will reveal the presence and frequency of sting jets over the southern hemisphere, North Pacific, and North Atlantic oceans, and continental Europe. This research will pave the way to a comprehensive evaluation of the impact of sting-jet cyclones in present and future years.

冬季风暴，正式名称为中纬度或温带气旋，是中纬度地区的主要自然灾害。尽管风力稍弱，但由于锋面长达 1000 多公里，它们造成的破坏与飓风一样大。损害可能来自狂风、暴雨和风暴潮，特强风的风暴通常称为风暴。自 2015 年以来，英国气象局已对所有影响英国、有可能引发琥珀色或红色天气警报的风暴进行了命名，以改善即将发生的潜在危险天气的沟通；通常每年会发生大约 7 场命名风暴（以及更多未命名风暴）。自 2004 年通过重新检查 1987 年十月大风暴的观测结果首次发现刺喷射流以来，在影响英国的一些最具破坏性的中纬度气旋中已经发现了刺喷射流。据报道，保险损失达 63 亿美元（按 2012 年价值计算），表明了这场风暴造成的损失。刺流是一种连贯气流，在数小时内从云头内下降，云头是一条向极地方向钩住强烈气旋中心的云带。这些喷流与其他寿命更长、规模更广、特征更明确的近地表风喷流不同。虽然它们的风足迹通常只有 50-100 公里宽，但它们可能会导致不同区域出现异常强烈的近地表风和破坏性阵风。自首次识别以来，我们对刺状喷射流动力学的理解有了很大进展，但主要是通过对穿越北大西洋影响西北欧的气旋的案例研究进行分析。最近公布了起源于地中海的单一喷气式飞机活动案例，但其他中纬度地区没有已公布的案例，而且已公布的气候学仅涵盖北大西洋。尽管如此，尚无已知的物理原因解释为什么刺状急流不应在其他洋盆上空形成，并且与刺状急流相关的大气不稳定类型已被证明在中纬度海洋上广泛存在。该项目将产生第一个全球刺射流气旋的气候学，并描述这些气旋和不包含刺射流的气旋之间的差异。我们将使用 Sting-jet 环境前兆工具来识别和跟踪再分析数据中的气旋。再分析数据提供了过去天气和气候的最完整表示，并且是通过将观测结果与使用一致的现代天气预报模型重新运行的天气预报相结合而生成的。刺急流的瞬态、相对小规模的性质以及与其产生相关的大气不稳定性类型意味着它们只能用具有非常高分辨率的模型来表示（即，运动方程在空间中紧密分离的点处求解），这些模型通常在数据周期和/或区域性质上受到限制。前兆工具旨在诊断有利于在数十年的全球数据集中形成尖刺射流的环境条件，例如重新分析，这些数据集的分辨率太粗，无法代表尖刺射流。这项工作将利用项目团队成员之前的工作来开发前兆，并在最近提高其计算效率，作为在英国气象局将其作为预测工具实施的工作的一部分（它用于预测实际输出） 时间），以及从最新的 ECMWF 再分析 ERA5（从 1979 年至今可用）得出的气旋轨迹的可用性。这些创新意味着全球气候学现在是可行的。由此产生的气候学将揭示南半球、北太平洋、北大西洋以及欧洲大陆上空的刺急流的存在和频率。这项研究将为全面评估当前和未来几年的喷射气旋影响铺平道路。