A multiscale modelling and simulation methodology for turbulent geophysical flows

湍流地球物理流的多尺度建模和模拟方法

• 批准号: RGPIN-2014-05831
• 负责人: Alam, Jahrul
• 金额: $ 0.8万
• 依托单位: Memorial University of Newfoundland
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611872
• 关键词: multiscale; modelling; simulation; methodology; turbulent

We live and breathe at the bottom of an atmosphere that contains both gases and tiny particles of dust and smoke. Our health and environment are affected by the very complex mechanisms of the extremely turbulent atmosphere. On a sunny day, the land warms up faster than the ocean, which drags cool air from over the ocean to the land. Through this process, energy is exchanged via enhanced turbulent mixing. Turbulent kinetic energy of hurricanes (and other natural disasters) causes damage to lives and their environment. Answering environmental questions - such as why hurricanes develop, why global temperature increases, why the rate of melting polar ice has increased, or why sea level rises - leans heavily on the complete understanding of the turbulent mixing and transport in the atmosphere. For example, in order to project the future distribution of such vital ingredients as carbon-dioxide (CO2) or other pollutants, one needs to know their sources and sinks, and how these pollutants are mixed in the turbulent atmosphere. However, the turbulent mixing mechanism is brutally affected when atmospheric models (either air pollution or weather prediction) employ a typical mesoscale grid at 10-20 km resolution. Our current modelling and simulation techniques are inadequate for representing turbulence at this truncated resolution, and have yet to approach a comprehensive development for parameterizing the truncated physics across a wide range of scales; note, there is a factor of about 100 million between the scale at which energy is added and that at which turbulent mixing occurs. One way to move forward is through the development of turbulent models for the atmospheric boundary layer under various conditions, and to utilize the gathered detailed knowledge on turbulence to parameterize unresolved physics of mesoscale meteorological models. My research program encompasses fundamental developments on a wavelet based multiscale methodology and its application to explain the influence of turbulence and other small scale meteorological variability on forecasting meso-scale phenomena. The proposed research thus aims to develop and exploit a robust, reliable, and computationally efficient new wavelet based dynamical core for a non-hydrostatic multiscale meteorological methodology over complex terrains. In contrast to contemporary atmospheric models, the proposed mesoscale modelling approach will capture the significant proportion of the flow with a multi-scale wavelet basis, and the residual motion will be parameterized. A multiscale parameterization technique will be developed for a two-way nesting of energetic eddies within a mesoscale model, employing the second generation wavelet transform. This new wavelet method will explore both the sub-mesoscale and sub-LES scale phenomena, which is an important aspect of the proposed development. In the field of atmospheric modelling, a faithful parameterization of boundary layer eddies or other convective phenomena on a mesoscale grid of 10-20 km resolution is one of the most challenging and demanding topics. Similarly, meteorological data may be available on the mesoscale resolution from a satellite; however, incorporating the observed meteorological feedback into the prediction of sub-mesoscale (e.g. a tornado) or micro-scale (e.g. boundary layer eddies) phenomena is necessary and also challenging. The success of the proposed wavelet based multiscale methodology for dynamically nesting turbulence and other small scale meteorological variability in a mesoscale model will advance state-of-the-art contemporary atmospheric models, thereby paving a new avenue toward the prediction of the mesoscale and the microscale weather phenomena.

我们生活和呼吸在大气层的底部，其中既有气体，也有灰尘和烟雾的微小颗粒。我们的健康和环境受到极其动荡的大气层非常复杂的机制的影响。在阳光明媚的日子里，陆地比海洋变暖得快，海洋把冷空气从海洋上空拖到陆地上。在这个过程中，能量通过增强的湍流混合进行交换。飓风（和其他自然灾害）的湍流动能对生命和环境造成损害。回答环境问题——比如为什么飓风会形成，为什么全球温度会升高，为什么极地冰融化的速度会加快，或者为什么海平面会上升——在很大程度上依赖于对大气中湍流混合和运输的完全理解。例如，为了预测二氧化碳（CO2）或其他污染物等重要成分的未来分布，人们需要知道它们的来源和汇，以及这些污染物如何在动荡的大气中混合。