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

极端天气，如强降水、持续时间长的冰暴和快速的气旋生成，可造成特别严重的后果，造成人员伤亡、洪水、海岸侵蚀和财产损失。科学家们一致认为，气候变暖是最近极端天气增加的原因，特别是降水。*我的研究计划的长期目标是加强我们对持续极端天气的理解和预测，这些极端天气往往会导致亚季节性气候状态。这些极端天气的相对较长的时间段通常超过了天气预报的可预测性的典型限制，走向一个只能从统计上预测未来大气状态的时间范围。这个从10天到1个月的扩展时间尺度被定义为“天气-气候界面”时间尺度。持续的天气制度增加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可能性。更好地理解这些极端现象将有利于学术研究人员与天气和气候科学家进行必要的综合和合作。*这项研究建议的最直接的短期目标包括从天气-气候交叉的角度对极端降水和气旋发生进行全面分析。在这些短期目标中隐含的假设是，降水和气旋发生是我们追求理解持续天气及其季节内变异性的关键分析过程。*我的研究侧重于基本热力学和动力学原理的分析，以此作为定义促进极端降水(包括冻雨和气旋发生)发展的环境的基础。这项研究包括气团、天气尺度强迫、静力稳定性、动态对流层顶急流和最大斜压增长率的分析。这些指标为降水和气旋发生提供了必要的环境条件，也是天气和气候模型的验证工具。此外，这些环境指标很容易从相对较粗分辨率的全球再分析中计算出来。*随后对这些天气和中尺度过程对行星尺度环境的负和正反馈分析将提供对气旋发生、降水和鼓励或阻碍它们存在的环境之间的一系列复杂相互作用的洞察。**

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.**