The Quasi-Biennial Oscillation (QBO) and Tropical Deep Convection

一段时间以来，赤道平流层准两年振荡(QBO)对热带系统的影响程度一直是一个悬而未决的问题，但几乎没有得到解决。近年来，平流层和对流层之间的动力相互作用引起了人们的极大兴趣，但关于平流层变化如何影响热带深部对流的研究工作很少。一些对大西洋飓风活动的预测使用了QBO作为预测指标之一，但还没有探索QBO和飓风之间的物理联系。本项目就是为了在这些问题上取得系统的进展，将利用观测和模拟的分析来研究准分子轨道对热带深部对流的可能影响。以前的观测分析和大气环流研究发现，准大气环流对热带深对流有重大影响；本项目解决了这些研究中的几个弱点。将使用一种云产品来消除OLR(传出长波辐射)资料中深对流和卷云之间的模糊性，并将ENSO(厄尔尼诺-南方涛动)对深对流的影响与QBO的影响分开。由于通过统计研究解决因果关系是困难的，如果不是不可能的话，将使用云解析和单列模拟来研究准分子轨道可能如何影响热带深部对流。云解析模型的背景状态将从高垂直分辨率的无线电探空数据中获得。该项目的广泛影响包括在一个结合了多种研究方法的项目中培训一名博士生：统计分析、云解析建模和大气环流建模，并使用最先进的高性能计算。这项工作应有助于阐明大西洋飓风活动预报器之一的物理基础，并阐明上层对流层-下层平流层区域模式所需的垂直分辨率，以便适当地解释上层对流层-下层平流层与热带深层对流的相互作用。

The extent to which the quasi-biennial oscillation (QBO) of the equatorial stratosphere affects tropical systems has been an open question for some time, but little has been resolved. In recent years, there has been great interest in dynamical interactions between the stratosphere and the troposphere, but little work on how stratospheric changes affect tropical deep convection. Some forecasts of Atlantic hurricane activity have used the QBO as one of the predictors, but the physical connection between the QBO and hurricanes has not been explored. This project is an effort to make systematic advances on these problems.Analyses of observations and modeling will be used to investigate the possible influence of the QBO on tropical deep convection. Previous observational analyses and general circulation studies found significant effects of the QBO on tropical deep convection; this project addresses several weaknesses in these studies. A cloud product that eliminates the ambiguity between deep convection and cirrus clouds in OLR (Outgoing Longwave Radiation) data will be used, and ENSO (El Nino-Southern Oscillation) influences on deep convection will be separated from those of the QBO. Because it is difficult, if not impossible, to address causality through statistical studies, cloud-resolving and single-column modeling will be employed to investigate how the QBO might affect tropical deep convection. Background states for the cloud resolving model will be obtained from high vertical-resolution radiosonde data.Broader impacts of this project include the training of a PhD student in a project that combines multiple research approaches: statistical analysis, cloud-resolving modeling, and general circulation modeling, and using state-of-the-art high-performance computing. This work should shed light on the physical basis for one of the predictors of Atlantic hurricane activity and on the vertical resolution needed in models of the upper troposphere-lower stratosphere region to properly account for upper troposphere-lower stratosphere interactions with deep tropical convection.