Turbulence Intermittency for Cloud Physics (TITCHY)

云物理的湍流间歇性 (TITCHY)

• 批准号: EP/Z000149/1
• 负责人: Oliver Buxton
• 金额: $ 221.74万
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FZ000149%2F1
• 关键词: Turbulence; Intermittency; Cloud; Physics; TITCHY

Since the dawn of humankind people have looked up at the sky, perhaps projected every day images into the dazzling variety of shapes that cumulus clouds produce, and asked "why do clouds form and then disappear?" and "why does it rain?" To this day these questions remain unanswered, although of course our understanding of the physics of clouds has advanced enormously. It has been provocatively asked "can we understand clouds without turbulence?" to which my response is a resounding "no!" Clouds grow by entraining environmental air across the sharply defined visible boundary of the cloud. Similarly they decay through precipitation, and more importantly the detrainment of air back to the environment. Neither of these processes are well understood. In recent years I have jump started the field of entrainment between two adjacent regions of turbulence, or turbulent/turbulent entrainment (TTE) which is precisely the scenario that occurs for a warm cumulus cloud in the turbulent atmospheric boundary layer. Entrainment dilutes a cloud and fundamentally alters its microphysics, yet TTE for a cloud is not understood in part because of its inherent intermittency. Without understanding the TTE of water mass, energy, momentum, buoyancy, and heat into a cloud it is not possible to parameterise it and thereby improve weather/climate forecasts. TITCHY will do this, through a carefully co-articulated campaign of state-of-the-art experiments and simulations specifically devised to assess the importance of my TTE paradigm to cloud microphysics. The second thrust of TITCHY is to examine the physics of water droplets within a cloud; in particular the forces that act on them and how they affect the collision/coalescence process that ultimately yields raindrops. These forces are subject to intermittent turbulent physics hitherto neglected but potentially of critical importance. Based on my transformative new ideas, TITCHY seeks to tackle a centuries-old problem with a modern outlook.

自人类诞生之日起，人们就抬头仰望天空，或许将每天的影像投射到积云产生的各种令人眼花缭乱的形状中，并问“为什么云会形成然后消失？”和“为什么下雨？”直到今天，这些问题仍然没有答案，尽管我们对云物理学的理解已经取得了巨大的进步。有人挑衅地问“我们能在没有湍流的情况下理解云吗？”我的回答是响亮的“不！”云通过夹带环境空气穿过云的清晰可见边界而生长。同样，它们会通过降水而腐烂，更重要的是，通过将空气带回环境中而腐烂。这些过程都没有被很好地理解。近年来，我开始研究两个相邻湍流区域之间的夹带领域，即湍流/湍流夹带（TTE），这正是湍流大气边界层中温暖积云发生的情况。夹带会稀释云并从根本上改变其微观物理性质，但云的 TTE 部分由于其固有的间歇性而未被理解。如果不了解云中水量、能量、动量、浮力和热量的 TTE，就不可能对其进行参数化，从而改善天气/气候预报。 TITCHY 将通过精心设计的最先进的实验和模拟活动来实现这一目标，这些实验和模拟专门设计用于评估我的 TTE 范式对云微物理的重要性。 TITCHY 的第二个目标是研究云中水滴的物理特性。特别是作用在它们上的力以及它们如何影响最终产生雨滴的碰撞/合并过程。这些力受到间歇性湍流物理的影响，迄今为止一直被忽视，但可能至关重要。基于我的变革性新想法，TITCHY 力求以现代视角解决一个存在数百年历史的问题。