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.

首席研究者将扩展有关利用数值模拟的大气对流的起始，结构和行为的事先研究。 这项研究的一部分专门研究挤压线风暴，部分侧重于与海风前线（SBF）和水平对流卷（HCR）相关的对流。 两者之间存在着相当大的和有利可图的协同作用，尤其是关于对流启动的研究。在quall线模拟中，在模型风暴的上游流入中通常看到的小扰动可以充当对流触发器，加快新的细胞形成，甚至保持有组织的对流。 这些扰动似乎是针对风暴动作和循环产生的，并居住在似乎由风暴本身预先解决的环境中，使这种开始更有利。 在SBF的情况下，边界层滚动提供（现在独立的）上游扰动。 SBF和HCR循环可以在没有现象可以隔离的情况下结合起来，从而产生深深的对流。两者和SBF/HCR现象都提供了影响对流引发的三个因素的有趣相互作用：运动学控制，湿度控制，水分控制和动态强迫。 运动学控制包括波，涡流等对对流启动或抑制的直接影响； HCR代表一个例子。 前面提到的预处理是一种水分控制：环境，响应暴风雨和周围的潜在加热和冷却，倾向于通过在暴风雨的上游环境中形成冷却和湿润的空气来调整，并且触发器往往会在这种舌头中形成。 这些触发因素可能在对流本身激发并穿过上游环境中激发的瞬态重力波中具有起源。这将代表动态强迫。这项研究中要使用的工具之一包括隔离云模型，该模型将用于灵敏度分析和动态跟踪。 伴随将在诸如对流启动研究之类的情况下具有重要用途，其中一个以上的过程或因素可能是活跃的，并且尚不清楚哪个是关键或原始的。这项研究的成功完成将使人们更好地了解对流沉淀系统的启动。