Are Antarctic ozone variations a manifestation of dynamics or chemistry?
Are Antarctic ozone variations a manifestation of dynamics or chemistry?
复制标题
南极臭氧变化是动力学还是化学的表现？
作者：
K. Tung;M. Ko;José María Rodríguez;N. Sze
Observations1–3reveal a large seasonal decrease in the column density of ozone during Antarctic early spring, followed by a rapid increase after October beyond its pre-spring value. Given the unique circumstances that exist in the Antarctic environment— relatively stable circumpolar vortex, cold air temperature achieved during polar night, and the increase in absorption of solar radiation by ozone as the Sun returns—we surmise the existence of a reverse circulation cell with rising motion in the polar lower stratosphere. The upwelling brings ozone-poor air from below 100 mbar to the stratosphere, possibly contributing to the observed ozone decline in early spring. At the same time, the Antarctic stratosphere might contain a very low concentration (<0.1 p.p.b.v. (parts per 109by volume) of NOx(NO + NO2), a condition that could favour a greatly enhanced catalytic removal of O3by halogen species2,4,5. We argue that heterogeneous processes and formation of OC1O by the reaction BrO + ClO → OClO + Br before and after the polar night might help to suppress the NOXlevels during the early spring period. However, the dilution of the concentrations of the chlorine species by the upwelling may reduce the effectiveness of the photochemical removal of O3.
