A Climatological Analysis of the Linkages between Tropopause Polar Vortices, Cold Pools, and Cold Air Outbreaks over the Central and Eastern United States

Abstract

AbstractCoherent vortices in the vicinity of the tropopause, referred to as tropopause polar vortices (TPVs), may be associated with tropospheric-deep cold pools. TPVs and associated cold pools transported from high latitudes to middle latitudes may play important roles in the development of cold air outbreaks (CAOs). The purpose of this study is to examine climatological linkages between TPVs, cold pools, and CAOs occurring in the central and eastern United States. To conduct this study, 1979–2015 climatologies of TPVs and cold pools are constructed using the ERA-Interim dataset and an objective tracking algorithm, and are compared to a 1979–2015 climatology of CAOs occurring in six NCEI-defined climate regions over the central and eastern United States. The climatologies of TPVs and cold pools indicate that central and eastern North America is a preferred corridor for their equatorward transport, and that the occurrence frequency of TPVs and cold pools is higher over northern regions of the United States compared to southern regions of the United States. Correspondingly, there is a higher percentage of CAOs linked to cold pools associated with TPVs over northern regions of the United States (32.1%–35.7%) compared to southern regions of the United States (4.4%–12.5%). TPVs and cold pools contributing to CAOs form most frequently over northern Canada and the Canadian Archipelago, and generally move southeastward toward southern Canada and the northern United States. TPVs and cold pools contributing to CAOs tend to be statistically significantly colder and longer lived when compared to all TPVs and cold pools transported to middle latitudes.