Radiative effects of ozone waves on the Northern Hemisphere polar vortex and its modulation by the QBO

Abstract

Abstract.The radiative effects induced by including interactive ozone, in particular, the zonally asymmetric part of the ozone field, have been shown to significantly change the temperature of the NH winter polar cap, and correspondingly the strength of the polar vortex. However, there is still a debate on whether this effect is important enough for climate simulations to justify the numerical cost of including chemistry calculations in long climate integrations. In this paper we aim to understand the 5 physical processes by which the radiative effects of including interactive ozone, and in particular the radiative effects of zonally asymmetric ozone anomalies (ozone waves), amplify to significantly influence the winter polar vortex. Using the NCAR Whole Atmosphere Community Climate Model in the natural configuration, in which ozone depleting substances and green house gases are fixed at 1960's levels, we find a significant effect on the winter polar vortex only when examining the QBO phases separately. Specifically, the seasonal evolution of the midlatitude signal of the QBO -the Holton-Tan effect -is 10 delayed by one to two months when radiative ozone wave effects are removed. Since the ozone waves affect the vortex in an opposite manner during the different QBO phases, when we examine the full time series, besides an early fall direct radiative effect, we find no statistically significant winter effect. We start by quantifying the direct radiative effect of ozone waves on temperature waves, and consequently on the zonal mean zonal wind, and show that this effect is most significant during early fall. We then show how the direct radiative effect amplifies by modifying the evolution of individual upward planetary wave 15 pulses and their induced mean flow deceleration during early winter when stratospheric westerlies just form and waves start propagating up to the stratosphere. The resulting mean-flow differences accumulate during fall and early winter, after which they get amplified through wave-mean flow feedbacks. We find that the evolution of these early-winter upward planetary wave pulses and their induced stratospheric zonal mean flow deceleration are qualitatively different between QBO phases, providing a new mechanistic view of the extratropical QBO signal (the Holton-Tan effect). We further show how these differences result 20 in an opposite effect of the radiative ozone wave perturbations on the mean flow deceleration for east and west QBO phases.

Influence of Arctic Stratospheric Ozone on Surface Climate in CCMI models

“…Higher values of ASO are associated with elevated geopotential height and warmer temperature over the polar lower and midstratosphere and lower geopotential heights, and colder temperatures in the tropical lower and mid-stratosphere in reanalysis data (Figures 2ab). This effect is consistent with previous work that has shown that transport controls lower stratospheric ozone concentrations (Douglass et al, 1985;Hartmann, 1981;Rood and Douglass, 1985;Hartmann and Garcia, 1979;Silverman et al, 2017).…”

“…Establishing the direction of causality between stratospheric polar cap ozone and temperature/height anomalies in the CCMI is beyond the scope of this work, as daily data is needed to resolve the key processes. However previous work has suggested that dynamical transport drives ozone anomalies in the lower stratosphere (Douglass et al (1985), Hartmann (1981), Rood and Douglass (1985), Hartmann and Garcia (1979), Silverman et al (2017)).…”

Prescribing Zonally Asymmetric Ozone Climatologies in Climate Models: Performance Compared to a Chemistry‐Climate Model

“…For example, all prescribed ozone simulations show a large temperature increase in the uppermost stratosphere and mesosphere, of about 17 K above 1 hPa, below which there is significant cooling of about 0.5 K between 60 ° S and 60 ° N extending into the tropical midstratosphere (not shown). This feature in the mesosphere was described by Sassi et al (), and these high‐altitude temperature differences have also been remarked upon in studies by Gillett et al (), McCormack et al (), Peters et al (), and Silverman et al () all of which compare zonally averaged ozone in a CCM to a fully interactive configuration. Sassi et al () attribute this feature to the nonlinear addition of variations in radiative heating over diurnal cycles and bands of longitude, that acts only on the diurnal component of ZAO (this dominates the ZAO pattern in the mesosphere and tropical upper stratosphere).…”

“…In the polar lower stratosphere during wintertime, zonal asymmetries in dynamics arising from waves and eddies may produce substantial zonally asymmetric features in the distribution of ozone (e.g., Hartmann, 1981). Recently, zonal asymmetries in ozone have been shown to play a substantial role in driving atmospheric circulation, independent of the zonal-mean structure of ozone in the atmosphere (e.g., Albers & Nathan, 2012;McCormack et al, 2011;Silverman et al, 2017). Additionally, a number of studies have explored the extent to which stratospheric ZAO has contributed to observed dynamical trends both in the stratosphere and at the surface, over recent decades (e.g., Crook et al, 2008;Gabriel et al, 2007;Gillett et al, 2009;Peters et al, 2015;Sassi et al, 2005;Waugh et al, 2009).…”

Impact of the Quasi-Biennial Oscillation on the Northern Winter Stratospheric Polar Vortex in CMIP5/6 Models

“…However, the Atmospheric Model Intercomparison Project (AMIP)-type simulations in previous studies usually show a much less robust and less consistent EQBO minus WQBO composite in the extratropics in CCMVal2 and CMIP5 models (Butchart et al 2018;Naoe and Yoshida 2019). Causes for a poor HT relationship in CMIP5/CCMVal2 experiments might include 1) shortness of data available (Naoe and Yoshida 2019); 2) nonlinear interactions with the 11-yr solar cycle (Salby and Callaghan 2000;Camp and Tung 2007;Labitzke and Kunze 2009;Matthes et al 2010;Scaife et al 2013;Gray et al 2016;Rao andRen 2017, 2018;Rao et al 2019a), El Niño-Oscillation (ENSO) SST anomalies (Garfinkel and Hartmann 2007;Wei et al 2007;Bell et al 2009;Calvo et al 2009;Ineson and Scaife 2009;Weinberger et al 2019;Rao and Ren 2016;Rao et al 2019b), and atmospheric internal variation in the AMIP-type run; 3) lack of interactive chemistry module and ozone feedbacks (Silverman et al 2018;Naoe and Yoshida 2019); and 4) insufficient improvements of the nonorographic gravity wave parameterization (Rind et al 2014;Geller et al 2016;Naoe and Yoshida 2019). In contrast, some of the models participating in the seasonal to subseasonal (S2S) project appear to simulate a HT effect statistically indistinguishable from that observed (Garfinkel et al 2018c).…”