Numerical Investigation of Convective Initiation and Maintenance

对流发生和维持的数值研究

• 批准号: 0139284
• 负责人: Robert Fovell
• 金额: $ 49.23万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0139284&HistoricalAwards=false
• 关键词: Numerical; Investigation; Convective; Initiation; Maintenance

The Principal Investigator will extend prior research concerning the initiation, structure and behavior of atmospheric convection utilizing numerical simulations. Part of the research is dedicated to the study of squall line storms and part focuses on convection associated with sea breeze fronts (SBFs) and horizontal convective rolls (HCRs). There is a considerable and profitable synergy between the two, particularly with regard to the study of convective initiation.In squall line simulations, the small perturbations that are often seen in the inflow just upstream of the model storms can act as convective triggers, expediting new cell formation and even keeping the organized convection active. These perturbations appear to be generated in response to storm motions and circulations and reside in a portion of the environment that appears to be preconditioned by the storm itself, making it more favorable for this initiation to occur. In the case of the SBF, the boundary layer rolls provide the (now independent) upstream perturbation. The SBF and HCR circulations can combine to create deep convection in situations where neither phenomenon could do so in isolation.Both the squall line and the SBF/HCR phenomena provide an interesting interplay of the three factors that influence convective initiation: kinematic controls, moisture controls and dynamical forcing. Kinematic controls include the direct effect of waves, vortices, etc., on convective initiation or inhibition; the HCRs represent one example. The aforementioned preconditioning is a moisture control: the environment, responding to latent heating and cooling in and around the storm, tends to adjust by creating a cooled and moistened tongue of air in the storm's immediate upstream environment, and the triggers tend to form in this tongue. These triggers may have their genesis in transient gravity waves excited by the convection itself and passing through the upstream environment; this would represent a dynamical forcing. One of the tools to be utilized in this research includes an adjoint cloud model, which will be used for sensitivity analysis and dynamical tracking. The adjoint will be of significant use in situations such as the convective initiation study, in which more than one process or factor may be active and it isn't clear which is the pivotal or primordial one. Successful completion of this research will lead to better understanding of the initiation of convective precipitating systems.

首席研究员将利用数值模拟扩展有关大气对流的启动，结构和行为的先前研究。 研究的一部分是致力于飑线风暴的研究，部分集中在与海风锋（SBF）和水平对流卷（HCR）相关的对流。 两者之间有相当大的和有益的协同作用，特别是在对流的研究initiation.In飑线模拟中，经常看到的小扰动，在入流上游的模式风暴可以作为对流触发器，加速新的单元的形成，甚至保持有组织的对流活跃。 这些扰动似乎是响应风暴运动和环流而产生的，并且存在于似乎由风暴本身预处理的环境中，使其更有利于这种启动的发生。 在SBF的情况下，边界层滚提供了（现在独立的）上游扰动。 SBF和HCR环流可以联合收割机在两种现象都不能单独产生深对流的情况下产生深对流。飑线和SBF/HCR现象都提供了影响对流产生的三个因素的有趣的相互作用：运动控制，湿度控制和动力强迫。 运动学控制包括波、涡流等的直接效果，对流启动或抑制; HCR代表一个例子。 前面提到的预处理是一种湿度控制：环境，对风暴内部和周围的潜热加热和冷却做出反应，往往会通过在风暴的上游环境中产生冷却和潮湿的空气舌来进行调整，而触发器往往会在这个舌中形成。 这些触发器可能起源于对流本身激发的瞬变重力波，并穿过上游环境;这将代表动力学强迫。在这项研究中使用的工具之一包括一个伴随云模型，它将用于敏感性分析和动态跟踪。 伴随将是重要的使用的情况下，如对流启动研究，其中一个以上的过程或因素可能是活跃的，它是不清楚的关键或原始的。这项研究的成功完成将导致更好地了解对流降水系统的启动。