Moist Absolutely Unstable Layer

大气对流的理论特征已经研究多年，不同形式的对流的基本特征被认为是众所周知的。首席研究员提出的观测证据表明，大气中出现了一种他称之为“潮湿的绝对不稳定层”(MAULS)的现象。预计这些层会在湍流中迅速消散，但首席调查员假设，在某些条件下，这些层的形成速度可能快于它们的消散速度。如果真的持续很长的时间和空间尺度，这可能对某些类型的大气对流有重要的影响。这项建议的主要目的是：(1)确定毛刺是如何产生和维持的；(2)确定毛刺的性质，并证明这些层的横向范围、深度和强度在建立湿对流翻转的组织模式中起着基础性作用。研究方法由三部分组成：(1)对现有的似乎显示毛刺的观测案例进行数值模拟；(2)数值敏感性实验，以确定不同的模型分辨率和人为改变毛刺的深度和强度的影响；(3)由三维分析初始化产生的理想化条件下的敏感性实验。预计从这项研究中获得的知识将加强对中尺度对流系统的组织和生命周期过程的基本理解。这些结果可能会带来实际的好处，例如改善短期(3至18小时)天气预报和全球气候模式中对流过程的参数化。研究结果也为湿绝对不稳定层的理论研究提供了依据。

The theoretical characteristics of atmospheric convection have been studied for many years and the basic characteristics of different forms of convection are considered to be well-known. The Principal Investigator presents observational evidence that a phenomenon that he terms "moist absolutely unstable layers" (MAULs) occur in the atmosphere. It would be expected that such layers would dissipate quickly through turbulence, but the Principal Investigator hypothesizes that under certain conditions, these layers may be created faster than they can be dissipated. If MAULs indeed do persist over long time periods and spatial scales, this may have important implications for certain types of atmospheric convection. The main objectives of this proposal are to: (1) determine how MAULs are created and maintained; (2) determine the properties of MAULs and demonstrate that the lateral extent, depth and intensity of these layers play a fundamental role in establishing the organizational mode of moist convective overturning. The research methodology consists of three parts: (1) numerical simulations of existing observational cases that appear to exhibit MAULs; (2) numerical sensitivity experiments to determine the effects of varying model resolution and artificially changing the depth and strength of MAULs; (3) sensitivity experiments on idealized conditions generated from three-dimensional analytical initializations. It is expected that knowledge gained from this research will enhance fundamental understanding of the organizational and lifecycle processes of mesoscale convective systems. The results potentially will provide practical benefits, such as improvements in short-term (3 to 18 hour) weather forecasts and in the parameterization of convective processes in global climate models. The results also should provide a basis for theoretical studies of moist absolutely unstable layers.