Abstract
Ozone feedback effects on the quasi-biennial oscillation (QBO) were investigated with a chemistry–climate model (CCM) by modifying ozone abundance in the radiative process. Under a standard run for 50 years, the CCM could realistically reproduce the QBO of about a 28-month period for wind and ozone. Five experiment runs were made for 20 years through varying ozone abundance only in the equatorial stratosphere from 100 to 10 hPa by −40, −20, −10, +10, and +20%, respectively, after the chemistry module and transferring the resultant ozone to the radiation calculation. It was found that the modification of ozone abundance in the radiation substantially changed the period of the QBO but slightly influenced the amplitude of the QBO. The 10% and 20% increase runs led to longer QBO periods (31 and 34 months) than that of the standard run, i.e., lengthening by 3 and 6 months, while the 10%, 20%, and 40% decrease runs resulted in shorter periods (24, 22, and 17 months), i.e., shortening by 4, 6, and 11 months. These substantial changes in the QBO period in the experiment runs indicate that the ozone feedback significantly affects the QBO dynamics through the modulation in solar heating.
Highlights
This paper is to investigate the ozone radiative feedback on the quasi-biennial oscillation (QBO) with a chemistry–climate models (CCMs) thoroughly holding the interaction between chemistry and dynamics
As a consequence of CCM simulations modifying the intensity of radiative feedback of interactive ozone in the equatorial stratosphere (100–10 hPa), the interactive ozone is demonstrated to have crucial effects on the dynamics of the QBO through radiation
The crucial effects of the ozone feedback on the QBO confirm the close relationship between ozone and dynamics in the stratosphere and imply that the interactive ozone is preferable for numerical models of seasonal forecast and future climate simulation in which the stratosphere plays a dominant role in longer timescales
Summary
Ozone thereby has crucial effects on the thermal structure in the middle atmosphere through radiation. For reliable assessment of ozone and dynamics in the recent past hindcast and future climate projection of the middle atmosphere, it is very preferable or indispensable to interactively incorporate ozone chemistry into numerical models as in chemistry–climate models (CCMs) (e.g., [3,4]). The basic mechanism of the QBO is attributed to the interaction with the mean flow of the waves propagating upward from the tropical troposphere at a broad range of spatiotemporal scales [9,10]. This paper will focus on the feedback effects of ozone through radiative (mostly solar) heating on the QBO, which some studies have demonstrated causes crucial modulations.
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