The Impact of a Changing Climate on the Frequency of Sudden Stratospheric Warming Events

Abstract

A sudden stratospheric warming (SSW) event is a rapid breakdown of the polar vortex during the winter months. Driven primarily by anomalous planetary-scale Rossby waves propagating upward from the troposphere, SSW events are able to influence tropospheric weather through stratospheric-tropospheric coupling. As a result of increased greenhouse gas emissions, temperatures are changing across the troposphere and may influence how the stratosphere and troposphere interact. It is unclear how the stratospheric circulation will respond to these changes and how the frequency of SSW events may be affected. This study uses National Center for Environmental Prediction and National Center for Atmospheric Research reanalysis data and four phase 5 Coupled Model Intercomparison Project (CMIP5) models to examine the frequency of SSW events in historical datasets from 1950–2005. Representative Concentration Pathways 4.5 and 8.5 are used to analyze how the frequency of SSW events from 2006–2100 differ from historical CMIP5 results. This study found there is a statistically significant increase in SSW events in the future. Mechanisms that influence the changes in SSW event frequency are discussed.