Tropical Cyclogenesis in the PRE-depression Investigation of Cloud-systems in the Tropics program (PREDICT): The Marsupial Paradigm in Action

知识价值：热带气旋的形成仍然是热带大气中一个突出的谜团，然而，正确理解飓风和台风是如何产生的，是将气候变化对这些风暴的影响和北美东部沿海地区恶劣天气的影响联系起来的第一步。从根本上说，热带气旋形成是一个中尺度过程，它将大尺度环流、天气波和中尺度过程（从热带波的临界层形成到云尺度上的涡状热塔）整合成一个中等尺度（20-200公里）的飓风单体。虽然在这个尺度上已经研究了许多相关的动力学和热力学过程，但实际上对它们在热带气旋形成的各个阶段的相对重要性、时间顺序和相互作用一无所知。一项实地活动（热带云系统低气压前调查；PREDICT）已被设计用于获得西大西洋热带低气压形成中尺度过程的现场测量。来自PREDICT野外活动的数据将与业务和回顾性气象分析、短期预报和卫星图像一起进行分析，以解决中尺度问题和跨多个尺度的物理过程的相互作用。由首席研究员和海军研究生院的同事开发的一种新的“有袋动物范式”将实时应用于PREDICT数据采集和解释工作。这种模式着重于热带波临界层（外中尺度，200-2000公里）在形成过程中的作用，以及母波“环流袋”内发展所必需的关键环境条件。本研究主要关注在环流袋中运行的中尺度过程，以及这些过程如何受到附近和内部环境条件的影响。PREDICT的一个零假设是，中尺度过程在热带气旋发生的大范围天气型中不会发生变化。根据这一观点，正是中尺度过程与环流潮湿的垂直环境相互作用的精确方式决定了风暴的发展是否成功。有袋动物范式为解释高分辨率大气数据和改进对过程的理解提供了必要的拉格朗日框架。现场数据的后期分析将与大规模分析相结合，以完善和扩展有袋动物范式。更广泛的影响：恶劣天气的公众教育对帮助社会利用天气信息和帮助他们了解环境非常重要。一个长期的问题是了解我们不断变化的气候是如何影响这些风暴及其影响的。当这些系统在许多情况下仍远离陆地时，对如何解释数据输入流的科学理解将得到改进，从而更可靠地对风暴状态进行分类，并更好地预测风暴形成和增强的可能性。

Intellectual Merit: Tropical cyclogenesis remains one of the outstanding mysteries of the tropical atmosphere, yet a proper understanding of how hurricanes and typhoons are born is the first of several steps in relating the effects of climate change on these storms and the impact of severe weather on coastal regions of eastern North America. Fundamentally a mesoscale process, tropical cyclogenesis integrates the large-scale circulation, synoptic waves, and mesoscale processes (ranging from critical layer formation in tropical waves to vortical hot towers on the cloud scale) into a hurricane monolith at intermediate scales (20-200 km). Although many of the relevant dynamical and thermodynamical processes at this scale have been investigated, virtually nothing is known about their relative importance, chronological sequence and mutual interaction in the various stages of tropical cyclogenesis. A field campaign (PRE-depression Investigation of Cloud systems in the Tropics; PREDICT) has been designed to obtain in situ measurements of mesoscale processes in developing tropical depressions in the western Atlantic. Data from the PREDICT field campaign will be analyzed in conjunction with operational and retrospective meteorological analyses, short-term forecasts and satellite imagery in order to address mesoscale issues and the interaction of physical processes across multiple scales. A new "marsupial paradigm" developed by the Principal Investigator and colleagues at the Naval Postgraduate School will be applied in real time to the PREDICT data acquisition and interpretation efforts. This paradigm focuses on the role of the tropical wave critical layer (outer mesoscale, 200-2000 km) in genesis, and on key environmental conditions that are necessary for development within the "gyre-pouch" of a parent wave. This study is concerned mainly with mesoscale processes operating in the gyre-pouch, and how these processes are affected by environmental conditions nearby and within. A null hypothesis of PREDICT is that mesoscale processes do not vary across a wide range of synoptic patterns in which tropical cyclogenesis occurs. According to this idea, it is the precise way that mesoscale processes interact with, and within, the gyre's moist vortical environment that determines whether storm development is successful. The marsupial paradigm provides the necessary Lagrangian framework for interpretation of high-resolution atmospheric data and for improved understanding of processes. Post-analysis of field data will be integrated with large-scale analyses to refine and extend the marsupial paradigm. Broader Impacts: Public education on severe weather is important to help society utilize weather information and to help them understand their environment. A longer-term concern is to understand how our changing climate has, and will, affect these storms and their impacts. An improved scientific understanding of how to interpret the data input stream will be passed on to the public in terms of a more reliable classification of storm status and better prediction of the likelihood of storm formation and intensification when these systems, in many cases, are still far from land.