The Effect of Moist Processes on Midlatitude Static Stability

在该补助金下进行的研究将研究位于温暖的热带和寒冷的极冠（即中纬度）之间的那部分大气（特别是对流层和平流层下部）的静态稳定性。 大气的静力稳定度是影响大气行为的许多方面的关键因素，包括对流降水的频率和强度、各种大气波动的传播速度、受科里奥利力强烈影响的大气环流模式所需的水平尺寸，甚至大气温室效应的强度。 稳定度是由温度随高度的垂直变化决定的，使高层大气相对于低层大气变暖的过程（即降低对流层温度随高度下降的速率）会导致静态稳定度的增加。 该项目的特别重点是大气水蒸气的凝结和伴随的潜热加热高层大气变暖对确定中纬度大气稳定性的重要程度。 许多以前的研究表明，中纬度大气的稳定性主要是由斜压不稳定性决定的，它可以粗略地认为是锋面系统的作用，其中来自南方的暖空气团被来自北方的冷空气团取代。 然而，一些研究表明，凝结加热可能有一个潜在的大的影响，静态稳定性，它是公认的，凝结加热与对流是一个主要的决定因素，在热带地区的静态稳定性。 在该资助下进行的研究将使用不同复杂程度的大气模型层次结构，结合最新和准确的观测数据集，以了解基本的物理和动力过程，通过水分影响中纬度stability.The determination of midlatitude static stability is a classic problem in fundamental atmosphere science，but it also has practical real world consequences. 首席研究员和其他人以前的工作表明，中纬度的稳定性随着全球变暖而增加，对水文循环可能产生重大影响。 除了更广泛的科学影响外，这项工作还将通过资助两名研究生来促进教育。 进行这项工作的科学家还将利用他们大学的资源制作一个简短的视频，向公众展示他们的研究成果。

Research conducted under this grant will study the static stability of that portion of the atmosphere (specifically the troposphere and lower stratosphere) which lies between the warm tropics and the cold polar caps (i.e. the midlatitudes). The static stability of the atmosphere is a key factor which influences many aspects of atmospheric behavior, including the frequency and intensity of convective precipitation, the propagation speed of various kinds of atmospheric wave motions, the horizontal size required for atmospheric circulation patterns to be strongly influenced by the Coriolis force, and even the strength of the atmospheric greenhouse effect. Stability is determined by the vertical variation of temperature with height, and processes which warm the upper atmosphere relative to the lower atmosphere (i.e. lessen the rate at which temperature decreases with height in the troposphere) cause an increase in static stability. The particular focus of this project is the extent to which the condensation of atmospheric water vapor and the attendant warming of the upper atmosphere by latent heating is important for determining the stability of the midlatitude atmosphere. Many previous studies have suggested that the stability of the midlatitude atmosphere is primarily determined by baroclinic instability, which can be thought of roughtly as the action of frontal systems in which warm air masses from the south are displaced by cold air masses from the north. However, some studies have shown that condensational heating could have a potentially large impact on the static stability, and it is generally accepted that condensational heating associated with convection is a primary determinant of static stability in the tropics. Research conducted under this grant will use a hierarchy of atmospheric models of varying degrees of complexity, in combination with the most recent and accurate observational datasets, to understand the fundamental physical and dynamical processes through which moisture influences midlatitude stability.The determination of midlatitude static stability is a classical problem in fundamental atmospheric science, but it also has practical real-world consequences. Previous work by the principal investigator and others shows that midlatitude stability increases with global warming, with potentially significant consequences for the hydrological cycle. In addition to the scientific broader impacts, the work would contribute to education by funding two graduate students. Scientists conducting the work will also present their research results to the public in a short video, prepared using the resources of their university.