Collaborative Research: Processes Determining the Climatology of Atmospheric Unstable Layers

这项研究旨在回答最近对大气中不同高度的不稳定层的观测所产生的一些问题;也就是说，这些层的特点是空气温度随高度下降。不稳定层是通过检查一个快速气象传感器来确定的，该传感器安装在从美国气象局操作的站发射的气象气球上。快速气象传感器可以每秒测量空气温度，即气球上升时每5米测量一次。不稳定层通常与湍流有关。在每个湍流层内，由于动能耗散，空气运动从大涡旋级联到小涡旋。大气湍流对飞行器的飞行具有危险性，并对遥感大气现象产生影响。该项目的研究人员将调查导致这些不稳定层的原因。了解这些不稳定层的起源可以提高飞机运行的安全性。最近，使用这种类型的快速气象气球传感器进行全球观测成为可能。研究人员还计划组织一次国际研讨会，以促进使用该数据集的国际研究。研究小组将回答两个主要问题：1）为什么在美国西部邻近地区的格林威治标准时间（GMT）午夜，平流层下部的不稳定层比格林威治标准时间中午更多，而在美国东部则相反？2)在科罗尔（7.3 N，134.5 E）近12公里高度处观测到的大量厚的不稳定层和相对缺乏较薄层的现象，也称为“凹口”，在其他近赤道台站是否存在？这个“缺口”与其他作者早先在同一大气区域中所指出的大气稳定度的最低值有什么关系？解决问题1的研究计划是设法查明导致平流层下部不稳定层的大气重力浮力波的时间和位置的差异。计划使用射线追踪方法进行这项工作。解决问题2的研究计划是将“缺口”特征的地理和时间变化与稳定性最小值的变化进行比较。研究人员还计划确定“缺口”功能与云内和云外流湍流。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

This research seeks to answer a number of questions that have arisen from recent observations of unstable layers at various altitudes in the atmosphere; that is, these layers are characterized with air temperature decreasing with height. Unstable layers have been identified by examining a fast meteorological sensor attached to meteorological balloons launched from stations operated by the United States (US) Weather Service. The fast meteorological sensor can take air temperature at every second, which is at every 5 meters as a balloon rises. Unstable layers are commonly associated with turbulence. Within each turbulent layer, air motions cascade from large eddies to small ones due to kinetic energy dissipation. Atmospheric turbulence is dangerous for aircraft operations and has impacts on remote sensing atmospheric phenomena. The researchers for the project will investigate what causes these unstable layers. Understanding of the origin of these unstable layers could improve safety of aircraft operations. Recently global observations using this type of fast meteorological balloon sensors become available. The investigators also plan to organize an international workshop to stimulate international research for using this dataset. The research team will answer two principal questions: 1) Why are there more unstable layers in the lower stratosphere at midnight Greenwich Mean Time (GMT) in the western contiguous US than at noon GMT, with the opposite being true in the eastern US? 2) Is the observed phenomenon of a great number of thick unstable layers and a relative paucity of thinner layers at near 12 km altitude at Koror (7.3 N, 134.5 E), which is also called “notch”, present at other near equatorial stations? In what way might this “notch” be related to the minimum in atmospheric stability that has been noted earlier by other authors in the same general atmospheric region? The research plan to address question 1 is to try to identify differences in the times and locations of atmospheric gravity buoyancy waves that lead to the lower stratospheric unstable layers. This is planned to be done using a ray-tracing methodology. The research plan to address question 2 is to compare the geographical and temporal variation of the “notch” feature to that of the stability minimum. The investigators also plan to identify the “notch” feature with in-cloud and cloud-outflow turbulence.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.