Extratropical Teleconnections of the QBO in the GISS Model E2.2

Abstract:

Observational studies have consistently linked the Quasi-Biennial Oscillation (QBO) to the stratospheric vortex and extratropical winter climate (Ebdon 1975, Naito & Hirota 1997, Scaife et al. 2014). Theoretical studies suggest that such a link is physically plausible, since the QBO has a large impact on the meridional temperature gradient and the propagation of planetary waves (Holton & Tan 1980, Garfinkel et al. 2012, Lu et al. 2014). However, models have overall struggled to reproduce QBO teleconnections. This is partly due to the paucity of models representing both the QBO and the extratropical stratosphere with high fidelity.

We investigate QBO–extratropical teleconnections using a model with a comparatively excellent stratosphere and convectively-sourced QBO: the NASA Goddard Institute for Space Studies (GISS) Model E2.2. Multiple forcings, chemistry configurations, and the use of ensemble members aid in reducing statistical and model uncertainties. We assess the impact of the QBO in this model on sudden stratospheric warmings (SSWs), extratropical surface extremes (including the Northern Annular Mode), and the unperturbed extratropical state (i.e., years without an SSW). We also consider the influence of SSWs on the QBO, in terms of its time-evolving amplitude and phase speed.