Phenomenological and Predictability Studies of Western North Pacific Tropical Cyclones in Relation to the Pacific Jet Stream

该项目将调查西北太平洋的热带气旋，重点是热带气旋的生命周期、路径和结构;热带气旋与北太平洋急流的相互作用;以及与西北太平洋热带气旋动态相关的北太平洋东部和北美的高影响天气事件。大气的可预测性将根据模型预报技能的传统统计措施加以处理，并将在个别西北太平洋热带气旋和下游高影响天气事件的背景下进行评估。这些项目的目标将通过对7月至12月在北太平洋西部上空发生的热带气旋（TC）的分析来实现，包括那些经历热带气旋外过渡（ET）和随后再增强为热带气旋外气旋（EC）的TC。 该分析将解决业务数值天气预报模型的能力，以预测西北太平洋热带气旋的事件和相关的高影响的天气事件发生在北太平洋东部和北美的下游;这些事件发生的大规模流态的行为;和大规模流态之间的过渡，发生在与这些事件。 将对热带气旋和北太平洋急流以及西北太平洋热带气旋的ET/EC相互作用进行多尺度调查，以了解初始分析和模式物理误差如何限制可预测性，并将通过对运行中的国家环境预报中心（NCEP）的技术进行天气学评估来完成全球预报系统，预测长达两周。该项目可能会通过隔离限制西北太平洋热带气旋和相关下游高压事件可预测性的因素来促进科学认识。在北太平洋东部和北美的影响天气事件，建立大规模的流动制度和制度转变，这些事件发生的可预测性的相对水平，并增加对高影响天气事件的预测技能的机制的理解。科学认识的预期进步可能会转化为对北太平洋东部和北美具有挑战性的高影响天气事件的预测，从而有利于美国的业务预报实践。

This project will investigate tropical cyclones (TCs) over the western North Pacific with emphasis on TC life cycle, track, and structure; TC interaction with the North Pacific jet stream; and high-impact weather events over the eastern North Pacific and North America that are linked dynamically to western North Pacific TCs. Atmospheric predictability will be addressed in terms of conventional statistical measures of model forecast skill, and will be assessed in the context of episodes of individual western North Pacific TCs and downstream high-impact weather events. These project goals will be accomplished through an analysis of recurving and transitioning TCs, including those TCs that undergo extratropical transition (ET) and subsequent reintensification as extratropical cyclones (ECs), over the western North Pacific from July through December. The analysis will address the ability of operational numerical weather prediction models to forecast episodes of western North Pacific TCs and associated high-impact weather events occurring downstream over the eastern North Pacific and North America; the behavior of large-scale flow regimes in which these episodes occur; and the transitions between large-scale flow regimes that take place in conjunction with these episodes. Multiscale investigations of interactions involving TCs and the North Pacific jet stream and the ET/EC of western North Pacific TCs will be conducted to understand how initial-analysis and model-physics errors limit predictability, and will be accomplished through the synoptic evaluation of the skill of the operational National Centers for Environmental Prediction (NCEP) Global Forecast System for projections out to two weeks.This project may be expected to advance scientific understanding by isolating factors that limit predictability for episodes of western North Pacific TCs and associated downstream high-impact weather events over the eastern North Pacific and North America, establishing the relative levels of predictability for the large-scale flow regimes and regime transitions in which these episodes occur, and increasing understanding of the mechanisms that govern the predictive skill of high-impact weather events. The anticipated advances in scientific understanding may be expected to translate into improved forecasts of high-impact weather events over the eastern North Pacific and North America that are challenging to predict, thereby benefiting operational forecasting practice in the U.S.