Cyclogenesis in a Tropical Wave Critical Layer: Vertical Structure of the "Wave Pouch" and Impacts of the Large-scale Environment

这项工作将通过对“有袋类动物模式”的进一步研究来解决热带气旋(以及被称为热带低压的低气压和近地表气旋风型的先行区)的起源问题。这一概念性模式指的是飓风形成理论，其中一种母大气扰动(称为“东风波”)的转换速度与环境气流相匹配，从而形成一个保护区(或所谓的“气囊”)，在这个保护区内，发展中的小尺度气旋环流(S)受到保护，不受恶劣环境条件的影响，直到进一步加强。这项研究将得到2010年国家科学基金会支持的预测(热带地区云系统的萧条前调查)实地活动期间收集的数据的支持，该活动涉及国家科学基金会/美国国家航空航天局GV研究机，以及美国国家航空航天局和美国国家海洋和大气局提供的补充资源。这项研究将集中在中α尺度波囊区(水平范围为200-2000公里)内的条件，它与大尺度环境的相互作用，以及这种相互作用对最终热带气旋形成的影响。它将结合来自预报场活动的飞行高度、探测和雷达数据、再分析数据、各种卫星数据集和WRF-ARW数值模式来解决三个主要问题：1)明确的波包是热带气旋发展的必要条件，如果是，它是如何形成的？2)为什么一些表现出深包的波没有发展成热带风暴？3)撒哈拉空气层(SAL)如何影响热带气旋的发生，为什么一些波包提供了保护，使其免受干燥空气的入侵，而另一些则不提供？这项工作的智力价值集中在利用重点预测数据集，结合在有袋类框架内进行的数值模式模拟，以更好地理解热带气旋发生。这项研究的更广泛影响包括对两名研究生的教育和培训，将工具和产品纳入课堂学习活动，以及支持从代表性不足的群体中抽调一名调查员。对社会的好处将来自于对热带气旋发生的更多了解和飓风形成预警提前时间的相关增加。

This effort will address the genesis of tropical cyclones (and antecedent regions of low pressure and near-surface cyclonic wind patterns termed tropical depressions) through further study of the "marsupial paradigm." This conceptual model refers to a theory of hurricane formation in which the translation speed of one type of parent atmospheric disturbance (termed an "easterly wave") is matched the environmental flow so as to create a protective zone (or so-called "pouch") in which developing small-scale cyclonic circulation(s) are protected from hostile environmental conditions until further strengthening occurs. This study will be supported by data to be collected during the 2010 NSF-supported PREDICT (PRE-Depression Investigation of Cloud-systems in the Tropics) field campaign involving the NSF/NCAR GV research aircraft as well as complementary resources being provided by NASA and NOAA. This research will focus on conditions within the meso-alpha scale wave pouch region (having 200-2000 km horizontal extent), its interaction with the larger-scale environment, and impacts of this interaction on ultimate tropical cyclone formation. It will incorporate flight-level, dropsonde and radar data from the PREDICT field campaign, with reanalysis data, various satellite datasets, and the WRF-ARW numerical model to address three main questions: 1) Is a well-defined wave pouch a necessary condition for tropical cyclone development, and if so, how does it form? 2) Why do some waves exhibiting a deep pouch fail to develop into a tropical storm? 3) How does the Saharan Air Layer (SAL) affect tropical cyclogenesis, and why do some wave pouches provide protection from dry air intrusion while others do not? The intellectual merit of this effort centers on exploitation of the focused PREDICT dataset in conjunction with numerical model simulations conducted in the marsupial framework to lead to better understanding of tropical cyclogenesis. Broader impacts of this research include the education and training of two graduate students and the integration of tools and products into classroom learning activities, as well as support for an investigator drawn from an underrepresented group. Benefits to society will come through the increased understanding of tropical cyclogenesis and associated increases in warning lead time for hurricane formation.