PRESTO (PREcipitation STructures over Orography)

PRESTO（地形上的 PREcipitation Structures）

• 批准号: NE/I024984/1
• 负责人: Suzanne Gray
• 金额: $ 34.88万
• 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: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI024984%2F1
• 关键词: PRESTO; PREcipitation; STructures; over; Orography

Flash floods cause loss of life and billions of pounds of damage each year within the UK, and take an additional toll on society through lasting impacts including a four-fold enhancement in the risk of depression. Because of the acute hazards and long-term consequences of these events, it is essential that they be accurately understood and predicted. Two of the three principal mechanisms behind UK flash-flooding events are convective storms and orographic precipitation (the other being frontal systems). Their impact has been reinforced in recent years by a series of devastating events. The Boscastle flood of 2004 and the Ottery St Mary's hailstorm of 2008 were both caused by quasi-stationary convective storms, and the Carlisle flood of 2005 and Cockermouth flood of 2009 were both caused by orographically enhanced rainfall. Although convection and orography may act independently to produce extreme rainfall, they are often closely linked over the complex UK terrain. The mechanical ascent upstream, over, and downwind of steep terrain and the thermally-driven ascent due to elevated heating are primary convection-initiation mechanisms in conditionally unstable flows. Because orography is fixed in space, these storms may anchor to specific terrain features and focus their precipitation over preferred areas. In particular, quasi-stationary precipitation bands are a manifestation of orographic convection that greatly increases flood risks because they focus heavy precipitation over specific regions. Such events are of particular concern over orographic watersheds, which, due to their steep gorges and confined basins, are highly susceptible to floods.Thanks to the high resolution radar systems, quasi-stationary convective bands have been observed over numerous mountain regions including Japan, the Mediterranean region, Rocky Mountains, Pacific Northwest United States, and Caribbean islands. The hydro-meteorological importance of these bands is reflected by the planned installation of a dedicated observational network for banded orographic convection over the French Massif Central during the upcoming Hydrological Cycle in the Mediterranean (HyMEX) programme. Although these bands also develop regularly over the UK, they have received little previous attention. Moreover, the majority of previous studies have focused on specific cases and have not generally identified the environmental conditions that favour their formation, the mechanisms that cause them to develop, or their predictability in numerical models.The proposed work will provide a leap forward in the understanding and prediction of quasi-stationary orographic convection in the UK and beyond. This will be achieved through an intensive climatological analysis over several regions of the globe where continuous radar data is available, which will identify the environmental conditions that support the bands and their characteristic locations and morphologies. Complementary high-resolution numerical simulations will pinpoint the underlying mechanisms behind the bands and their predictability in numerical weather prediction models. This work will provide positive impacts for the forecasting community, general public, and other academics in the field. Forecasters will benefit from the identification of simple diagnostics that can be used operationally to predict these events based on available model forecasts and/or upstream soundings. A series of activities are proposed to directly engage with forecasters to effectively disseminate our findings. The public will benefit from improved forecasting of potentially hazardous precipitation events. The academic community will benefit from the advanced physical understanding (which will be disseminated through conferences, workshops, and peer-reviewed publications) and the numerous international collaborations associated with this project.

山洪每年在英国造成生命损失和数十亿英镑的损失，并通过持久的影响对社会造成额外的损失，包括抑郁症风险增加四倍。由于这些事件的严重危害和长期后果，必须准确理解和预测它们。英国暴洪事件背后的三个主要机制中有两个是对流风暴和地形降水（另一个是锋面系统）。近年来，一系列毁灭性的事件加强了它们的影响。2004年的波士顿洪水和2008年的奥特里圣玛丽冰雹都是由准静止对流风暴引起的，2005年的卡莱尔洪水和2009年的科克茅斯洪水都是由地形增强型降雨引起的。虽然对流和地形可能独立作用产生极端降雨，但在复杂的英国地形上，它们往往紧密相连。在条件不稳定气流中，上游、上方和下风的机械上升以及升温引起的热驱动上升是主要的对流启动机制。由于地形在空间中是固定的，这些风暴可能会固定在特定的地形特征上，并将降水集中在首选地区。特别是，准静止降水带是地形对流的一种表现，由于它们将强降水集中在特定区域，因此大大增加了洪水风险。这类事件对地形分水岭尤其令人关切，因为这些分水岭由于其陡峭的峡谷和受限制的盆地，极易受到洪水的影响。得益于高分辨率雷达系统，在日本、地中海地区、落基山脉、美国西北太平洋地区和加勒比岛屿等许多山区观测到准静止对流带。这些波段的水文气象重要性反映在计划在即将到来的地中海水文循环（HyMEX）方案期间在法国中部地块安装一个专门的带状地形对流观测网。虽然这些乐队也经常在英国发展，但他们之前很少受到关注。此外，以前的大多数研究都集中在具体的案例上，并没有普遍确定有利于它们形成的环境条件，导致它们发展的机制，或它们在数值模式中的可预测性。提出的工作将提供一个飞跃的理解和预测准平稳地形对流在英国和超越。这将通过对全球几个地区进行密集的气候分析来实现，这些地区可以获得连续的雷达数据，这将确定支持波段及其特征位置和形态的环境条件。互补的高分辨率数值模拟将查明这些带背后的潜在机制及其在数值天气预报模式中的可预测性。这项工作将对预测界、公众和该领域的其他学者产生积极影响。预报员将受益于简单诊断的识别，这些诊断可用于基于可用的模型预测和/或上游探测来预测这些事件。建议开展一系列活动，直接与预报员接触，以有效传播我们的发现。公众将受益于对潜在危险降水事件的改进预报。学术界将受益于先进的物理理解（将通过会议、研讨会和同行评审出版物传播）以及与该项目相关的众多国际合作。

项目成果

The generation of rainbands downwind of mountainous terrain

山地顺风雨带的产生

• 发表时间: 2018
• 作者: Wright Carly Jayne

A radar-based rainfall climatology of Great Britain and Ireland

英国和爱尔兰基于雷达的降雨气候学

• DOI: 10.1002/wea.2486
• 发表时间: 2015
• 期刊: Weather
• 影响因子: 1.9
• 作者: Fairman J

The Utility of Convection-Permitting Ensembles for the Prediction of Stationary Convective Bands

允许对流系综在预测静止对流带中的用途

• DOI: 10.1175/mwr-d-15-0148.1
• 发表时间: 2016
• 期刊: Monthly Weather Review
• 影响因子: 3.2
• 作者: Gray S

Climatology of Banded Precipitation over the Contiguous United States

美国本土带状降水的气候学

• DOI: 10.1175/mwr-d-16-0015.1
• 发表时间: 2016
• 期刊: Monthly Weather Review
• 影响因子: 3.2
• 作者: Schultz D

Nonclassic evolution of a cold-frontal system across the western United States during the Intermountain Precipitation Experiment

山间降水实验期间美国西部冷锋系统的非经典演化

• DOI: 10.1175/waf-d-19-0166.1
• 发表时间: 2020
• 期刊: Weather and forecasting
• 影响因子: 2.9
• 作者: Schultz, D. M.;Steenburgh, W. J.
• 通讯作者: Steenburgh, W. J.