Collaborative Research: Topographic Influences on Extreme Warm-Season Precipitation

合作研究：地形对极端暖季降水的影响

• 批准号: 1854443
• 负责人: Alison Nugent
• 金额: $ 33.66万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1854443&HistoricalAwards=false
• 关键词: Collaborative; Research; Topographic; Influences; Extreme

Extreme rainfall affects millions of people globally, yet our understanding and forecast skill of this high-impact weather phenomenon is limited. The Prediction of Rainfall Extremes Campaign in the Pacific (PRECIP, May-August 2020) field campaign aims to improve understanding of the multi-scale processes important for generating extreme rainfall in the moisture-rich environment of Taiwan and the western North Pacific. The overarching PRECIP hypothesis is that extreme rainfall results from an optimal combination of multi-scale ingredients in a moisture-rich environment, but different key ingredients and processes lead to strong vertical forcing and high rainfall intensity, strong horizontal forcing and long duration, or a mixture of both intense and sustained precipitation.Intellectual Merit:This project focuses on orographic influences on extreme rainfall, using a unique combination of radar and radiosonde observations on both sides of Taiwan's Central Mountain Range (CMR) to determine the role of steep terrain in enhancing both intensity and duration of rainfall through a combination of thermodynamic, dynamic, kinematic, and microphysical processes. The overall hypothesis is that terrain enhances both intensity and duration of extreme rainfall through increasing the magnitude of ingredients needed to produce heavy rainfall. In addition to promoting lifting and concentrating moisture, terrain modifies rainfall intensity and duration through changes in microphysical processes. In the subtropical environment of Taiwan, efficient warm-rain processes can produce high intensity convective rainfall, while ice-based processes become increasingly important for long-duration events dominated by stratiform precipitation. Additionally, results from TiMREX 2008 suggest that upslope tilting of relatively shallow convection along Taiwan's CMR can promote growth of precipitation-sized ice. Subsequent cold-pool generation leads to continuous growth of cells upstream and prolongs the duration of rainfall events along the CMR. PRECIP offers the opportunity to further explore the role of terrain, including the influence on microphysical processes, in producing extreme rainfall for a wide variety of events, both on the western slopes and along the data-sparse east coast of Taiwan. To test the above hypotheses, the study will use a combination of PRECIP data from multi-frequency dual-polarization Doppler radars (S-PolKa, SEA-POL), radiosondes, and models to explore terrain-influenced processes for diurnally-forced convection, mesoscale convective systems embedded within the Meiyu front, and tropical cyclones.Broader Impacts:An important broader goal of this investigation is to determine which of the key ingredients and processes identified for Taiwan extreme rainfall events are also relevant to orographic precipitation in other environments or locations. The team of three early-career female scientists brings a wealth of knowledge of observational field projects and terrain-influenced precipitation studies spanning a variety of global regimes, including warm-season rainfall in the Sierra Madre Occidentals, CMR, Andes, Rockies, and Himalayas, typical trade-wind flow, a tropical cyclone passing over Dominica, and cold-season rainfall over the Olympics. PRECIP will give an opportunity to investigate a wide variety of rain-producing events, both the windward and leeward sides of the mountain range. The findings from this project will have the potential to provide an updated understanding of extreme rainfall globally by building off an ingredients-based framework through unprecedented data collected in a wide variety of heavy rain events.This project is jointly funded by the Established Program to Stimulate Competitive Research (EPSCoR) and PREEVENTS, Prediction of and Resilience against Extreme Events program.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

极端降雨影响着全球数百万人，但我们对这种高影响天气现象的理解和预测能力有限。太平洋极端降雨预测活动（PRECIP，2020 年 5 月至 8 月）实地活动旨在提高对在台湾和西北太平洋富含水分的环境中产生极端降雨的重要多尺度过程的了解。 PRECIP 的总体假设是，极端降雨是由富含水分的环境中多尺度成分的最佳组合产生的，但不同的关键成分和过程导致强垂直强迫和高降雨强度、强水平强迫和长持续时间，或者智力优势：该项目重点研究地形对极端降雨的影响，利用台湾中央山脉（CMR）两侧的雷达和无线电探空仪观测的独特组合来确定陡峭地形在增强降雨方面的作用两个都通过热力学、动力学、运动学和微物理过程的结合来确定降雨的强度和持续时间。总体假设是，地形通过增加产生强降雨所需成分的强度来增强极端降雨的强度和持续时间。除了促进水分上升和集中之外，地形还通过微物理过程的变化改变降雨强度和持续时间。在台湾的亚热带环境中，高效的暖雨过程可以产生高强度的对流降雨，而冰基过程对于以层状降水为主的长期事件变得越来越重要。此外，TiMREX 2008 的结果表明，沿着台湾 CMR 的相对较浅的对流的上坡倾斜可以促进降水大小的冰的生长。 随后的冷池生成导致上游细胞的持续生长，并延长了 CMR 沿线降雨事件的持续时间。 PRECIP 提供了进一步探索地形在为各种事件产生极端降雨方面的作用（包括对微物理过程的影响）的机会，无论是在西坡还是在数据稀疏的台湾东海岸。为了检验上述假设，该研究将结合使用多频双极化多普勒雷达（S-PolKa、SEA-POL）、无线电探空仪和模型的 PRECIP 数据来探索昼夜强制对流的地形影响过程，梅雨锋内嵌的中尺度对流系统和热带气旋。 更广泛的影响：这项调查的一个重要的更广泛的目标是确定台湾极端天气的关键成分和过程降雨事件也与其他环境或地点的地形降水有关。由三名职业生涯早期女性科学家组成的团队带来了丰富的实地观测项目和跨越各种全球状况的地形影响降水研究的知识，包括西马德雷山脉、CMR、安第斯山脉、落基山脉和喜马拉雅山脉的暖季降雨、典型的信风流、经过多米尼加的热带气旋以及奥运会上空的冷季降雨。 PRECIP 将提供调查各种降雨事件的机会，包括山脉的迎风面和背风面。该项目的研究结果将有可能通过在各种暴雨事件中收集的前所未有的数据构建基于成分的框架，从而提供对全球极端降雨的最新了解。该项目由既定刺激计划共同资助竞争性研究 (EPSCoR) 和预防、极端事件预测和恢复力计划。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。