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

赤道平流层准两年一次振荡（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，人们对平流层和对流层之间的动力学相互作用非常感兴趣，但对平流层变化如何影响热带深对流的研究很少。一些大西洋飓风活动的预报使用了QBO作为预测因子之一，但尚未探讨QBO与飓风之间的物理联系。这个项目是在这些问题上取得系统进展的一项努力。观测分析和模拟将用于研究QBO对热带深对流可能产生的影响。以往的观测分析和大气环流研究发现，QBO对热带深层对流有显著影响；这个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）数据中深层对流和卷云之间的歧义，并将厄尔尼诺-南方涛动（ENSO）对深层对流的影响与QBO的影响分开。由于很难（如果不是不可能的话）通过统计研究来解决因果关系，因此将采用云分辨和单列模型来研究QBO如何影响热带深层对流。云分辨模式的背景状态将从高垂直分辨率无线电探空数据中获得。该项目更广泛的影响包括在一个项目中培训一名博士生，该项目结合了多种研究方法：统计分析、云解析建模和一般环流建模，并使用最先进的高性能计算。这项工作将阐明大西洋飓风活动预测器之一的物理基础，以及对流层上层-平流层下层区域模式所需的垂直分辨率，以便正确地解释对流层上层-平流层下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.