Analysis of extreme precipitation and cyclogenesis at the weather-climate interface

天气-气候界面的极端降水和气旋发生分析

• 批准号: RGPIN-2016-04916
• 负责人: Gyakum, John
• 金额: $ 3.5万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=689638
• 关键词: Analysis; extreme; precipitation; cyclogenesis; weather

Weather extremes in the form of heavy precipitation, long-duration ice storms, and rapid cyclogenesis can have especially significant consequences in the form of human injuries and fatalities, flooding, coastal erosion and property losses. There is a consensus among scientists that a warming climate is responsible for recent increases in such extremes, particularly precipitation.***The long-term objective of my research program is to enhance our understanding and forecasting of persistent weather extremes that often contribute to the sub-seasonal climate state. The relatively long time periods of these weather extremes typically exceed the typical limit of a weather forecast's predictability, towards a time range in which the future atmospheric state can only be predicted statistically. This extended time scale, ranging from 10 days to one month is defined to be the “weather-climate interface” time scale. Persistent weather regimes enhance the durations of precipitation and dry conditions, and thus increase the chances of heavy precipitation and droughts. An improved understanding of these extremes will benefit academic researchers with a needed synthesis and collaboration of weather and climate scientists.***The most immediate shorter-term objectives of this research proposal include comprehensive analyses of extreme precipitation and cyclogenesis from a weather-climate intersection perspective. Implicit in these shorter-term objectives is the assumption that precipitation, and cyclogenesis, are key processes to analyze in our pursuit of understanding persistent weather and its intra-seasonal variability.***My research focuses on analyses of fundamental thermodynamic and dynamic principles as foundations for defining environments that facilitate the developments of extreme precipitation, including freezing rain, and cyclogenesis. This research includes analyses of air masses, synoptic-scale forcing, static stability, the dynamic tropopause jet stream, and maximum baroclinic growth rates. These metrics provide the necessary environmental conditions for precipitation and cyclogenesis, and also serve as validation tools for both weather- and climate-models. Furthermore, these environmental metrics are readily computed from the relatively coarse-resolution global reanalyses.***Subsequent analyses of feedbacks, both negative and positive, of these synoptic- and meso-scale processes onto the planetary-scale environments will provide insight into the complex set of interactions among cyclogenesis, precipitation, and the environment that either encourages or discourages their existence.**

以强降水、长时间冰暴和快速气旋形成为形式的极端天气可能造成特别严重的后果，包括人员伤亡、洪水、海岸侵蚀和财产损失。科学家们一致认为，气候变暖是最近这种极端事件增加的原因，尤其是降水。***我的研究计划的长期目标是提高我们对经常导致亚季节气候状态的持续极端天气的理解和预测。这些极端天气的相对较长的时间周期通常超过天气预报可预测性的典型限制，接近一个只能通过统计来预测未来大气状态的时间范围。这个从10天到一个月的扩展时间尺度被定义为“天气-气候界面”时间尺度。持续的天气状况延长了降水和干旱条件的持续时间，从而增加了强降水和干旱的机会。对这些极端现象的更好理解将有利于学术研究人员，他们需要天气和气候科学家的综合和合作。***本研究计划最直接的短期目标包括从天气-气候交叉角度对极端降水和气旋形成进行全面分析。在这些短期目标中隐含的假设是，在我们追求理解持续天气及其季节内变化的过程中，降水和气旋形成是分析的关键过程。***我的研究重点是分析基本的热力学和动力学原理，作为定义环境的基础，促进极端降水的发展，包括冻雨和气旋形成。这项研究包括气团、天气尺度强迫、静态稳定性、对流层顶动态急流和最大斜压增长率的分析。这些指标为降水和气旋形成提供了必要的环境条件，也可作为天气和气候模式的验证工具。此外，这些环境指标很容易从相对粗分辨率的全球再分析中计算出来。***对这些天气尺度和中尺度过程对行星尺度环境的负反馈和正反馈的后续分析，将有助于深入了解气旋形成、降水和环境之间复杂的相互作用，这些相互作用可能会促进或阻碍它们的存在