Cumulus Convection and Large-Scale Tropical Flows

这项资助下的研究将完善和扩展我们对热带对流云和降水的热力学控制的理解，包括热带气旋（飓风）、对流耦合开尔文波、热带东风波（可以发展成飓风）和马登-朱利安振荡。该研究结合了简单模型、野外观测和云解析模型（CRM）来确定控制热带对流及其与大尺度大气环流的关系的最重要的物理过程。该项目的具体任务将包括：1)推广集体拟平衡理论。热带对流的准平衡状态在许多关于热带环流动力学的理论文献中被假设，但在CRM模拟中没有得到充分的发展。本研究将使用简单的模型来理解准平衡理论隐含的局限性；2)对流耦合热带波Raymond-Fuchs模式的推广。Raymond-Fuchs模式已经成功地再现了对流耦合波，提出的扩展将用于研究与观测到的热带对流相关的头重、底重和倾斜加热剖面的影响；3)探讨对流在热带气旋发展中的作用。研究将探讨热带气旋发展过程中垂直对流质量通量的性质，特别是质量通量在多大程度上发生在少数强烈的“涡状热塔”中，而不是发生在大量的普通云层中；4)研究东风波的结构和动力学，特别是它们的发展在多大程度上受地面风速、温度、湿度、风切变和地面热湿通量的控制。该项目将支持和培养两名研究生和一名本科生，从而培养下一代热带对流领域的科学家。研究生将通过参与NSF PREDICT项目获得大型野外活动的经验。这项工作将通过克罗地亚一名科学家的合作支持国际科学合作，并将通过在斯普利特举行的一次讲习班促进国际科学推广。这项工作具有更广泛的科学影响，因为它与开发用于天气和气候模式的积云参数化方案的任务有关。

Research under this grant will refine and extend our understanding of the thermodynamic control of tropical convective clouds and precipitation over a broader range of tropical weather systems including tropical cyclones (hurricanes), convectively coupled Kelvin waves, tropical easterly waves (which can develop into hurricanes), and the Madden-Julian oscillation. The research uses a combination of simple models, observations from field campaigns, and a cloud resolving model (CRM) to identify the most important physical processes which govern tropical convection and its relationship to the large-scale atmospheric circulation. Specific tasks of the project would include 1) Extension of the theory of covective quasi-equilibrium. The quasi-equilibrium state for tropical convection which is assumed in much of the theoretical literature on tropical circulation dynamics does not develop fully in CRM simulations. This research will use simple models to understand the implied limitations of quasi-equilibrium theory; 2) Extension of the Raymond-Fuchs model of convectively coupled tropical waves. The Raymond-Fuchs model has been successful in reproducing convectively coupled waves, and the proposed extensions would be used to study the effects of top-heavy, botttom-heavy, and tilted heating profiles associated with observed tropical convection; 3) Examination of the role of convection in the development of tropical cyclones. The research would address the nature of the vertical convective mass flux in tropical cyclone development, paticularly the extent to which the mass flux happens in a few intense "vortical hot towers" rather than a large number of unexceptional clouds; 4) Examination of the structure and dynamics of easterly waves, particularly the extent to which their development is controlled by surface wind speed, temperature, humidity, wind shear, and surface fluxes of heat and moisture.The project will support and train two graduate students and one undergraduate, thereby training the next generation of scientists in the field of tropical convection. The graduate students will gain experience with large field campaigns through participation in the NSF PREDICT project. The work will support international collaboration in science through the collaboration of a scientist in Croatia, and international scientific outreach will be promoted through a workshop held in Split. The work has broader scientific impact due to its relevance to the task of developing cumulus parameterization schemes for use in weather and climate models.