The Dynamics of Stratospheric Warmings and Their Connection to Northern Annular Mode Variability

该项目将研究平流层对北半球中高纬度对流层变率的动力学影响。最近，观测分析重新点燃了人们对平流层环流的兴趣，包括突然变暖，这些分析表明，极地纬度对流层变化的一个主要模式--环状模式--受到平流层环状异常向下迁移的影响。平流层极涡的变化与对流层纬向平均纬向风和环流模式(如北极涛动/北大西洋涛动)的季节性异常有关。这些模式对欧洲和北美的气候和天气产生了深远的影响。奥特兰博士和邓克顿博士将对对流层和平流层以及亚热带和中纬度地区的耦合机制进行动态定向分析。PI将使用准线性原始方程模式来研究纬向平均纬向流(环状分量)与行星尺度Rossby波的相互作用。该项目将促进对对流层和平流层动力相互作用的理解和模拟，并阐明环状模式的演变。这项研究也将有助于理解产生观测到的气候趋势的机制。

The project will investigate the dynamical influence of the stratosphere on tropospheric variability in the middle and high latitudes of the Northern hemisphere. Interest in stratospheric circulation, including sudden warming, has recently been rekindled by observational analyses which suggest that a primary mode of tropospheric variability in polar latitudes--the annular mode--is influenced by the downward migration of annular anomalies from the stratosphere. Variations in stratospheric polar vortex have been linked to seasonal anomalies in the tropospheric zonal-mean zonal winds and circulation patterns such as the Arctic Oscillation/North Atlantic Oscillation. These patterns have profound impact on European and North American climate and weather. Drs. Ortland and Dunkerton will conduct a dynamically oriented analysis of the mechanisms coupling the troposphere and stratosphere, and the subtropics and midlatitudes. The PIs will use a quasi-linear primitive equation model to study the interaction of zonal-mean zonal flow (annular component) and the planetary-scale Rossby waves. The project will advance the understanding and modeling of dynamical interactions of the troposphere and stratosphere, and shed light on the evolution of the annular mode. This research will also be helpful in understanding the mechanisms producing the observed climate trends.