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引发、结构和行为的先前研究。 该研究的一部分致力于研究飑线风暴，一部分侧重于与海风锋（SBF）和水平对流卷（HCR）相关的对流。 两者之间存在相当大且有利可图的协同作用，特别是在对流引发的研究方面。在飑线模拟中，模型风暴上游流入中经常看到的小扰动可以充当对流触发器，加速新的对流引发。细胞形成，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先调节的环境的一部分中，使其更有利于这种启动的发生。 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 环流可以结合起来产生深层对流，而这两种现象都无法单独产生深层对流。飑线和 SBF/HCR 现象都提供了影响对流启动的三个因素之间有趣的相互作用：运动学控制、湿度控制和动力强迫。 运动学控制包括波、涡流等对对流引发或抑制的直接影响； HCR 就是一个例子。 上述预处理是一种湿度控制：环境对风暴内部和周围的潜在加热和冷却做出反应，往往会通过在风暴的直接上游环境中产生冷却和湿润的空气舌来进行调整，并且触发因素往往会在这种情况下形成。舌头。 这些触发因素可能源于对流本身激发并穿过上游环境的瞬态重力波；这将代表一种动力强迫。本研究中使用的工具之一包括伴随云模型，它将用于敏感性分析和动态跟踪。 伴随现象在对流起始研究等情况下将具有重要作用，在这种情况下，可能有多个过程或因素处于活跃状态，并且不清楚哪一个是关键或原始的。这项研究的成功完成将有助于更好地了解对流降水系统的启动。