Numerical Investigation of Convective Initiation and Maintenance

首席研究员将利用数值模拟扩展先前关于大气对流的开始、结构和行为的研究。部分研究致力于研究飑线风暴，部分研究与海风锋（SBFs）和水平对流卷（hcr）相关的对流。这两者之间有相当大的和有益的协同作用，特别是在对流起始的研究方面。在飑线模拟中，在模型风暴上游流入气流中经常出现的小扰动可以作为对流触发因素，加速新单体的形成，甚至保持有组织的对流活跃。这些扰动似乎是对风暴运动和环流的响应而产生的，并且存在于似乎由风暴本身预置的部分环境中，使其更有利于风暴的发生。在SBF的情况下，边界层卷提供了（现在是独立的）上游扰动。在两种现象都不能单独发生的情况下，SBF和HCR环流可以结合起来形成深层对流。飑线和SBF/HCR现象都提供了影响对流开始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。运动学控制包括波浪、漩涡等对对流产生或抑制的直接影响；hcr就是一个例子。前面提到的预调节是一种湿度控制：环境，对风暴内部和周围的潜在加热和冷却做出反应，倾向于通过在风暴的直接上游环境中创造一个冷却和湿润的空气舌来进行调整，而触发器往往在这个舌中形成。这些触发器的成因可能是由对流本身激发的瞬态重力波经过上游环境；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，该模型将用于灵敏度分析和动态跟踪。伴随式在诸如对流起始研究之类的情况下具有重要的用途，在这种情况下，可能有多个过程或因素是活跃的，并且不清楚哪个是关键的或原始的。这项研究的成功完成将有助于更好地理解对流降水系统的起源。

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.