Collaborative Research: Understanding Tropical Cyclone Evolution in Wind Shear through a Synthesis of Observational Data Sets and Idealized Simulations

热带气旋强度的变化仍然是一个难以理解的过程。即使超出实时预报的范围，利用更全面的分析，有时仍然无法解释为什么在明显相似的情况下，一个热带风暴或飓风会减弱，而另一个却会增强。我们无法理解（更不用说预测）这些事件对沿海社区来说仍然是一个潜在的危险，这些社区很容易受到可能迅速加剧的飓风登陆的影响。知识价值：一般来说，环境风切变值的增加对热带气旋的增强越来越不利。然而，意想不到的（和无法预测的）强化情况通常与中等风切变值有关。本研究的目的是更好地理解风切变、热带气旋结构和热带气旋增强之间的关系，重点研究中度风切变的情况。这将通过综合过去和最近的实地项目中获得的观测数据集以及高分辨率数值模型模拟分析来实现。特别是，最近开发的一种建模技术允许在高度控制的环境下进行理想化的模拟，这种环境可以指定为与观测到的热带气旋周围的环境几乎相同。这些模拟将根据气旋内部的观测结果进一步验证。一旦观测到的风暴和模拟的风暴达到了令人满意的一致，模拟就可以用来理解引起这些情况下强度和结构变化的物理过程。此外，理想化的建模技术允许周围环境的各个方面——风、温度和湿度剖面——独立变化。因此，在个案的基础上，将有可能分离出这些因素中哪一个对风暴的增强（或减弱）有最大的控制。这将使人们对热带气旋周围的环境如何调节其结构和强度，以及强度变化在多大程度上是由内部或外部驱动的有了新的认识。更广泛的影响：该项目将提高我们对热带气旋强度和结构变化的环境控制的认识。更深入的了解将不仅通过改进模式发展，而且通过根据环境探测确定新的或改进的预报参数，从而改进预报。该项目将使用现有的数据集，并产生和传播从最近的实地项目获得的原始观测数据得出的新数据集。该项目将支持两名研究生的教育和培训。

Tropical cyclone intensity change remains a difficult process to understand. Even beyond the context of real-time forecasting and with the benefit of a more comprehensive analysis, it is still sometimes impossible to explain why, in apparently similar situations, one tropical storm or hurricane will weaken while another will become stronger. Our inability to understand (let alone forecast) these events remains as a potential danger to coastal communities which are vulnerable to the possibility of a rapidly intensifying hurricane making landfall.Intellectual merit: In general, increasing values of environmental wind shear are increasingly less favorable for tropical cyclone intensification. However, cases with unexpected (and unforecasted) intensification are often associated with moderate values of wind shear. The goal of this research is to better understand the relationships between wind shear, tropical cyclone structure, and tropical cyclone intensification, with an emphasis on cases of moderate wind shear. This will be achieved through a synthesis of observational data sets obtained in past and recent field programs as well as analyses of high-resolution numerical model simulations. In particular, a recently developed modeling technique allows for the production of idealized simulations with highly controlled environments that can be specified to be nearly identical to the environments around observed tropical cyclones. These simulations will be further validated against observations from within the cyclones. Once satisfactory agreement between the observed and simulated storms is achieved, the simulations can be used to understand the physical processes that caused intensity and structure change for those cases. Furthermore, the idealized modeling technique allows all aspects of the surrounding environment - the wind, temperature, and humidity profiles, to be varied independently. Thus it will be possible, on a case-by-case basis, to isolate which of these factors have the most control over intensification (or decay) of the storm. This will lead to a new understanding of how the environment surrounding a tropical cyclone modulates its structure and intensity, and to what extent intensity changes are either internally or externally driven.Broader impacts: This project will lead to improvement of our understanding of environmental controls of tropical cyclone intensity and structure change. Greater understanding will lead to improved forecasting, not only through improved model development, but also through the identification of new or improved forecasting parameters based on the environmental soundings. The project will put to use existing datasets as well as lead to the generation and dissemination of new data sets derived from the raw observations obtained from recent field projects. The project will support the education and training of two graduate students.