Studies on hurricanes: Intensity change and early genesis

飓风研究：强度变化和早期起源

• 批准号: RGPIN-2015-04023
• 负责人: Yau, ManKong(Peter)
• 金额: $ 1.6万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=669267
• 关键词: Studies; hurricanes; Intensity; change; early

Hurricanes are violent vortices in the atmosphere. For hurricane prediction, two major problems remain. One is to forecast the rapid intensification (RI) of the storm and the other is to forecast when a storm will form.***Convection in the eyewall can affect RI in two ways. First, latent heating released in cloud processes is a main source of energy. Its spatial distribution affects RI especially when bursts of convection occur inside the radius of maximum wind. Second, latent heating in the eyewall produces a hollow tower of potential vorticity (PV) that supports propagating vortex Rossby waves (VRW) which may become unstable to mix eyewall PV into the eye to effect intensity change. Additionally, VRWs in a hurricane vortex can radiate gravity waves leading to another instability known as radiative pumping. However, this instability can be damped at a critical radius outside the vortex core where the angular velocity of the waves matches the fluid rotation rate. The understanding of these instabilities is important to improve hurricane forecasting. ***Atlantic hurricanes are often initiated from easterly wave disturbances out of Africa, but only a small fraction ever develop into a tropical storm. A recent theory stipulates that tropical cyclogenesis is favored in a pouch which is similar to the cat's eye recirculation region within the critical layer of the parent wave. However, there are no comprehensive studies on how a pouch forms. ***The objective of the proposed research program is to advance our understanding of hurricane intensity change and early tropical cyclogenesis through theoretical analysis, high resolution modeling, and diagnostic studies. The relevant scientific questions to answer are:***a) How microphysical processes regulate the distributions of latent heating and water loading which may bear strongly on hurricane intensity? ***b) How do instabilities and the critical radius affect hurricane intensity change?***c) How does a pouch form during the early genesis stage of a hurricane?***Theoretical analysis, high resolution computer modeling, and diagnostic studies will be brought to bear to yield answers to the above questions. ***The research program will improve our understanding of hurricane intensity change and the mechanism for genesis. It will help in the forecasting of these violent systems. *****

飓风是大气中的暴力涡流。对于飓风预测，仍然存在两个主要问题。一种是预测暴风雨的快速强化（RI），另一种是预测何时会形成风暴。***对流在Eyewall中可以通过两种方式影响RI。首先，在云过程中释放的潜在加热是主要能源的来源。它的空间分布会影响RI，尤其是当对流爆发发生在最大风的半径内时。其次，眼墙中的潜在加热产生了一个潜在的涡度（PV）的空心塔，该塔支持繁殖的涡流rossby波（VRW），这可能会变得不稳定，无法将Eyewall PV混合到眼睛中以效应强度变化。此外，飓风涡流中的VRW可以辐射重力波，导致另一种被称为辐射泵的不稳定性。但是，这种不稳定性可以在涡流芯外面的临界半径下抑制，其中波的角速度与流体旋转速率相匹配。对这些不稳定性的理解对于改善飓风预测很重要。 ***大西洋飓风通常是从非洲的东风障碍中引发的，但只有一小部分变成了热带风暴。 最近的理论规定，热带环生成是有利于袋中的，该小袋类似于猫的眼睛再循环区域内父伴的临界层。但是，没有关于小袋如何形成的全面研究。 ***拟议的研究计划的目的是通过理论分析，高分辨率建模和诊断研究来促进我们对飓风强度变化和早期热带环生成的理解。要回答的相关科学问题是：*** a）微物理过程如何调节潜在加热和水负荷的分布，这可能强烈影响飓风强度？ *** b）不稳定性和临界半径如何影响飓风强度的变化？*** c）在飓风的早期创世记阶段中如何形成一个小袋？***理论分析，高分辨率计算机建模和诊断研究将带来以产生上述问题的答案。 ***研究计划将提高我们对飓风强度变化的理解和创世纪的机制。它将有助于预测这些暴力系统。 *****