Diabatic influences on mesoscale structures in extratropical storms

非绝热对温带风暴中尺度结构的影响

• 批准号: NE/I005218/1
• 负责人: Douglas Parker
• 金额: $ 37万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI005218%2F1
• 关键词: Diabatic; influences; mesoscale; structures; extratropical

The project is aimed at a better understanding and prediction of mesoscale structures in synoptic-scale storms. Such structures include fronts, rain bands, secondary cyclones, sting jets etc, and are important because much of the extreme weather we experience (e.g. strong winds, heavy rain) comes from such regions. Weather forecasting models are able to capture some of this activity correctly, but there is much still to learn. By a combination of measurements and modelling, mainly using the Met Office Unified Model (UM), we will work to better understand how mesoscale processes in cyclones give rise to severe weather and how they can be better represented in models and better forecast. The project is organised into three broad work packages. The first of these aims to look at real mesoscale structures in the atmosphere, using high-resolution in situ and radar measurements to derive their morphology and dynamics. The key to the latter is to calculate the production of potential vorticity by diabatic processes - especially phase changes of water (vapour/liquid/ice) and air-sea fluxes of sensible and latent heat. The associated high-resolution modelling programme will use the UM to simulate a representative number of events, diagnosing the PV tendency in the model and comparing with the measurements. Sensitivity studies and further diagnostics with the model will reveal the sensitivity of the forecasts to the correct representation of these processes and the dynamical consequences of diabatically-generated PV, both on the mesoscale and larger scales. Two student projects will investigate the role of boundary-layer processes in storm behaviour and conduct a statistical investigation of mesoscale precipitation features, based on archived radar and wind profiler data. The second WP examines particular physical processes and the way these are represented in forecast models. Convection cannot be explicitly represented in current large-scale models (it is just beginning to be resolvable by high-resolution local-area models) so it needs to be parameterised. The schemes that are used are not optimised for mid-latitude storms, where convection often initiates at altitude rather than at the Earth's surface. A combination of novel diagnostics and new (or modified) schemes aimed at improving the representation of convection will be developed in this WP. Also addressed here will be the derivation of air-sea fluxes of heat and momentum from aircraft flights, and their use (as part of a larger, ongoing international project) to derive a better parameterisation for these quantities in high wind conditions. Lastly, microphysical measurements made with the FAAM aircraft will be used to derive latent heating/cooling rates as a function of the microphysical environment and used to improve the model simulations in the first WP and to improve microphysical parameterisations in the UM The final WP addresses the problem of predictability, using a combination of ensemble and data assimilation techniques. A unique archive of forecast ensembles produced at the Met Office will be exploited to determine how well the forecast ensemble actually generates realistic mesoscale features, and the skill with which this is done (using standard measures of skill). Model errors in representing convection, air-sea fluxes and microphysics will be investigated to determine their impact on the forecasts for different flow conditions. The relationship between different model variables on the mesoscale is poorly known at present and this will be investigated using ensembles and the results of the measurement programme. Finally, novel approaches to data assimilation will be investigated through a student project.

该项目旨在更好地理解和预测天气尺度风暴中的中尺度结构。这些结构包括锋面、雨带、次级气旋、刺急流等，并且很重要，因为我们经历的大部分极端天气（例如强风、大雨）都来自这些地区。天气预报模型能够正确捕捉其中的一些活动，但仍有很多东西需要学习。通过测量和建模的结合，主要使用气象局统一模型（UM），我们将努力更好地了解气旋中的中尺度过程如何引起恶劣天气，以及如何在模型中更好地表示它们并更好地进行预报。该项目分为三大工作包。第一个目标是利用高分辨率原位和雷达测量来观察大气中真实的中尺度结构，以获得它们的形态和动力学。后者的关键是计算非绝热过程产生的位涡，特别是水（蒸气/液体/冰）的相变以及感热和潜热的海气通量。相关的高分辨率建模程序将使用 UM 模拟代表性数量的事件，诊断模型中的 PV 趋势并与测量结果进行比较。敏感性研究和模型的进一步诊断将揭示预测对这些过程的正确表示的敏感性以及非绝热产生的PV的动力学后果，无论是在中尺度还是更大尺度上。两个学生项目将研究边界层过程在风暴行为中的作用，并根据存档的雷达和风廓线仪数据对中尺度降水特征进行统计调查。第二个工作组研究了特定的物理过程以及这些过程在预测模型中的表示方式。对流无法在当前的大型模型中明确表示（它刚刚开始可以通过高分辨率局部区域模型来解析），因此需要对其进行参数化。所使用的方案并未针对中纬度风暴进行优化，其中对流通常在高空而不是地球表面开始。本工作组将开发新颖的诊断方法和新的（或修改的）方案的组合，旨在改善对流的表示。这里还将讨论从飞机飞行中推导海空热通量和动量，以及使用它们（作为一个更大的、正在进行的国际项目的一部分）来为强风条件下的这些量导出更好的参数化。最后，使用 FAAM 飞机进行的微物理测量将用于导出作为微物理环境函数的潜在加热/冷却速率，并用于改进第一个 WP 中的模型模拟以及改进 UM 中的微物理参数化。使用集合和数据同化技术的组合来解决可预测性问题。将利用英国气象局生成的预报集合的独特档案来确定预报集合实际生成真实中尺度特征的效果以及完成此操作的技能（使用标准技能测量）。将研究代表对流、海气通量和微物理的模型误差，以确定它们对不同流动条件的预测的影响。目前，人们对中尺度上不同模型变量之间的关系知之甚少，这将使用系综和测量程序的结果进行研究。最后，将通过学生项目研究数据同化的新方法。

项目成果

Meteorology of Tropical West Africa - The Forecasters' Handbook

热带西非气象学 - 预报员手册

• DOI: http://dx.10.1002/9781118391297.ch3
• 发表时间: 2017
• 作者: Lafore J

Meteorology of Tropical West Africa - The Forecasters' Handbook

热带西非气象学 - 预报员手册

• DOI: http://dx.10.1002/9781118391297.ch4
• 发表时间: 2017
• 作者: Parker D

Research flight observations of a prefrontal gravity wave near the southwestern UK

研究英国西南部附近前额重力波的飞行观测

• DOI: http://dx.10.1002/wea.632
• 发表时间: 2010
• 期刊: Weather
• 影响因子: 1.9
• 作者: Knippertz P

Cloud Banding and Winds in Intense European Cyclones: Results from the DIAMET Project

欧洲强旋风中的云带和风：DIAMET 项目的结果

• DOI: http://dx.10.1175/bams-d-13-00238.1
• 发表时间: 2015
• 期刊: Bulletin of the American Meteorological Society
• 影响因子: 8
• 作者: Vaughan G

Meteorology of Tropical West Africa - The Forecasters' Handbook

热带西非气象学 - 预报员手册

• DOI: http://dx.10.1002/9781118391297.ch2
• 发表时间: 2017
• 作者: Cornforth R