Simulations of Ozone Feedback Effects on the Equatorial Quasi-Biennial Oscillation with a Chemistry–Climate Model

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.