The role of post-tropical cyclones for European extreme weather

后热带气旋对欧洲极端天气的作用

• 批准号: 2285991
• 金额: --
• 依托单位: University of Reading
• 依托单位国家: 英国
• 项目类别: Studentship
• 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=studentship-2285991
• 关键词: role; post; tropical; cyclones; European

While Europe is not directly affected by North Atlantic tropical cyclones, some of these cyclones do recurve and transform into midlatitude storms during extratropical transition reaching Europe as so-called post-tropical cyclones (PTCs). One such storm, Ophelia, made landfall over Ireland in October 2017 and caused loss of life as well as widespread damage and shutdown of economic activity. The reinsurance sector are now becoming aware of the risk from such storms and the risk modelling community are starting to incorporate these types of storms into their models.While individual storms such as Ophelia have received considerable attention, much remains unknown about the climatological role of PTCs for Europe in the historical period, and how this role might change with global warming. There is tentative evidence from single climate model simulations, for example, that more PTCs may affect Europe in the next century due to a warmer sea surface in the northeast Atlantic (Haarsma et al., 2013; Liu et al., 2017).In this PhD project, the following research questions will be addressed:- How special are PTCs for Europe, i.e. how different are they from the entire population of midlatitude storms reaching Europe in terms of where and when they occur through the annual cycle, what their structure is, and how strong the associated surface impacts (wind/waves, precipitation) are?- How do the properties of PTCs depend on (i) the properties of the original tropical cyclone, (ii) on the midlatitude westerly flow during extratropical transition, and (iii) on the sea surface temperature field? For example, do particularly strong PTCs originate from particularly strong tropical cyclones?- How does the latest generation of high-resolution global climate models represent PTCs, and how are they predicted to change over the next century? Will more of them affect Europe, and more strongly so? Do different models agree on predicted PTC changes, including across different storylines of atmospheric circulation change (Zappa & Shepherd, 2017)?The student will work closely with the High Resolution Global Climate Modelling Group at NCAS and the Met Office, and thereby gain access to a set of high-resolution climate simulations, for example those currently prepared CMIP6-HighResMIP/PRIMAVERA, and/or more recent available simulations. Model resolution has been shown to be important for representing tropical cyclones (e.g., Roberts et al., 2015) and also the North Atlantic storm track (Zappa et al., 2013). One initial aim for this project will be to evaluate the role of model resolution for representing extratropical transition and PTCs. Having improved insights into storms undergoing extratropical transition and their impact on western Europe will lead to improvements in how well they are represented in the reinsurance risk models.Haarsma, R. J., Hazeleger, W., Severijns, C., De Vries, H., Sterl, A., Bintanja, R., et al. (2013). More hurricanes to hit western Europe due to global warming. Geophysical Research Letters, 40(9), 1783-1788. https://doi.org/10.1002/grl.50360Roberts, M. J., Vidale, P. L., Mizielinski, M. S., Demory, M.-E., Schiemann, R., Strachan, J., et al. (2015). Tropical cyclones in the UPSCALE ensemble of high-resolution global climate models. Journal of Climate, 28(2). https://doi.org/10.1175/JCLI-D-14-00131.1 Zappa, G., Shaffrey, L. C., & Hodges, K. I. (2013). The Ability of CMIP5 Models to Simulate North Atlantic Extratropical Cyclones*. Journal of Climate, 26(15), 5379-5396. https://doi.org/10.1175/JCLI-D-12-00501.1 Zappa, G., & Shepherd, T. G. (2017). Storylines of atmospheric circulation change for European regional climate impact assessment. Journal of Climate, 30(16), 6561-6577. https://doi.org/10.1175/JCLI-D-16-0807.1Liu, M., Vecchi, G. A., Smith, J. A., & Murakami, H. (2017). The Present-Day Simulation and Twenty-First-Century Projection of the Climatology of Extratropical Transition in the North Atlantic

虽然欧洲没有受到北大西洋热带气旋的直接影响，但其中一些气旋确实在到达欧洲的温带过渡期间重新出现并转化为中纬度风暴，称为后热带气旋(PTCs)。其中一场名为奥菲莉亚的风暴于2017年10月在爱尔兰登陆，造成生命损失以及大范围的破坏和经济活动关闭。再保险部门现在开始意识到这类风暴的风险，风险建模社区开始将这些类型的风暴纳入他们的模型。虽然像Ophelia这样的个别风暴受到了相当大的关注，但对于PTC在历史时期对欧洲的气候学作用，以及这种作用可能如何随着全球变暖而改变，人们仍然知之甚少。例如，有来自单一气候模式模拟的初步证据表明，由于东北大西洋海面变暖，下个世纪可能会有更多的PTCs影响欧洲(Haarsma等人，2013年；在这一博士项目中，将讨论以下研究问题：--临时热带气旋对欧洲有多大的特殊性，即它们在全年周期中发生的地点和时间与到达欧洲的整个中纬度风暴有什么不同，它们的结构是什么，以及相关的地面影响(风/浪、降水)有多大？-临时临时热带气旋的性质如何取决于(1)原始热带气旋的性质，(2)温带外过渡期间的中纬度西风气流，以及(3)海表面温度场？例如，特别强的临时热带气旋是否源自特别强的热带气旋？-最新一代的高分辨率全球气候模式如何代表临时临时热带气旋，以及它们在下个世纪将如何变化？它们中的更多会影响欧洲，而且影响会更大吗？不同的模型是否对预测的PTC变化达成一致，包括大气环流变化的不同故事情节(Zappa&Shepherd，2017)？学生将与NCAS的高分辨率全球气候建模小组和英国气象局密切合作，从而获得一套高分辨率气候模拟，例如目前准备的CMIP6-HighResMIP/Primavera，和/或更新的可用模拟。模型分辨率已被证明对于代表热带气旋(例如，Roberts等人，2015年)和北大西洋风暴路径(Zappa等人，2013年)很重要。该项目的一个初步目标是评估模式分辨率在代表温带过渡和临时热带气候变化方面的作用。对经历温带过渡的风暴及其对西欧的影响有了更好的洞察力，将导致在再保险风险模型中表现得更好。(2013年)。由于全球变暖，西欧将遭遇更多飓风袭击。地球物理研究通讯，40(9)，1783-1788。Https://doi.org/10.1002/grl.50360Roberts，M.J.，Vidale，P.L.，Mizielinski，M.S.，Demory，M.E.，Schiemann，R.，Strachan，J.(2015)。高分辨率全球气候模式集合中的热带气旋。《气候杂志》，28(2)。Https://doi.org/10.1175/JCLI-D-14-00131.1 Zappa，G.，Shaffrey，L.C.，&Hodges，K.I.(2013年)。CMIP5模式模拟北大西洋温带气旋的能力*。《气候杂志》，26(15)，5379-5396。Https://doi.org/10.1175/JCLI-D-12-00501.1 Zappa，G.和Shepherd，T.G.(2017年)。欧洲区域气候影响评估大气环流变化的故事情节。《气候杂志》，30(16)，6561-6577。Https://doi.org/10.1175/JCLI-D-16-0807.1Liu，M.，Vecchi，G.A.，Smith，J.A.和Murakami，H.(2017)。北大西洋温带过渡气候学的现代模拟和21世纪预测