Balanced and Unbalanced Mesoscale Dynamics

小行星9417304 大规模的大气系统，如低压和高压中心，通常由压力梯度和科里奥利力的平衡控制，因此称为平衡流。 对于小尺度的现象，如雷暴，这种平衡通常不成立，这些天气特征被称为由不平衡流控制。 主要研究者将对这两种流动类型进行数值和理论研究。 密度流特征、飑线和中尺度涡旋是重要的中尺度天气生成系统，其持续时间往往长于单个对流风暴。 这些长期存在的中尺度结构可能涉及平衡的大尺度流动和更短暂的小尺度运动之间的不同类型的相互作用。 研究相关的平衡动力学与不平衡动力学可能会导致一个新的理解为什么有关的结构是长寿的。 中尺度对流系统中的平衡（或不平衡瞬变）流分量很可能受大尺度环境流的确定性（或随机性）控制。 识别中尺度对流系统中的平衡和非平衡气流分量，可以为改进或发展数值天气或气候预报模式的云参数化方案提供有用的信息。 ***

9417304 Xu Large scale atmospheric systems such as low and high pressure centers are typically governed by a balance of pressure gradient and coriolis forces and are, therefore, termed balanced flow. For small-scale phenomena such as thunderstorms, this balance typically does not hold and these weather features are referred to as being governed by unbalanced flows. The Principal Investigator will perform a numerical and theoretical study of these two flow types. Density current features, squall lines and mesoscale vortices are important mesoscale weather producing systems and often persist over timescales longer than individual convective storms. These long-lived mesoscale structures may involve different types of interactions between the balanced large scale flows and more transient small scale motions. Studying the related balanced dynamics versus unbalanced dynamics may lead to a new understanding of why the concerned structure is long-lived. The balanced (or unbalanced transient) flow component in a mesoscale convective system is likely to be controlled deterministically (or stochastically) by the large scale environmental flow. Identifying the balanced and unbalanced flow components in mesoscale convective systems may provide useful information for improving or developing cloud parameterization schemes for numerical weather or climate prediction models. ***