Diagnostic model study of the seasonal variation of global ozone and the Antarctic ozone hole

A simple two‐dimensional model is constructed to simulate and gain an understanding of the global distribution of ozone and its seasonal variation. In the model the Chapman cycle parameterized by Hartmann (1978) is used. The time dependence of the diffusion coefficients is neglected, except in the polar regions. The effects of the meridional circulation, consisting of the following three components, are taken into account: (1) an annually varying component due to the annual variation in the heating of ozone, oxygen, and water vapor, which is assumed to be anti‐symmetric (symmetric with a 6 month shift) about the equator; (2) a nonseasonal, steady component of the transport circulation with ascending air in the tropics and descending air in the middle and high latitudes of both hemispheres; and (3) an annually varying component of the transport circulation which represents planetary wave activity, strong convection in the tropics, and other seasonally variable factors. Although the employed circulations and diffusion coefficients are ad hoc, the simple model simulates the main features of the global distribution of ozone and its seasonal variation. The Antarctic ozone hole is discussed from a global point of view. The possibility of a weak October minimum in the Antarctic total ozone amount, without introducing chlorine chemistry, is suggested.