Effects of interannual variation of temperature on heterogeneous reactions and stratospheric ozone

A two-dimensional chemical/dynamical/microphysical model is used to calculate the effect of temperature interannual variability on stratospheric ozone. Two effects associated with temperature variations are considered in this paper: First, the effect on the rate coefficient of heterogeneous reactions occurring at the surface of sulfate aerosols, in particular for the enhanced sulfate aerosols following the eruption of Mount Pinatubo, and second, the effect of temperature interannual variations on the formation of polar stratospheric clouds (PSCs) and the spring Antarctic ozone depletion. The interannual variabilities of ozone concentrate affected by both the processes are evaluated. The model results show that during winter 1992-1993, stratospheric temperature at high latitudes in the northern hemisphere is colder than during winter 1991-1992, leading to a larger rate of heterogeneous conversion from inactive chlorine to active chlorine in sulfate aerosols during winter 1992-1993 than during winter 1991-1992 at northern high latitudes. As a result, ozone reduction due to heterogeneous reactions following the eruption Mount Pinatubo is enhanced in a colder winter (1992-1993) and reduced in a warmer winter (1991-1992). This result indicates that the enhanced heterogeneous conversion associated with colder temperature can explain, in part, the large ozone depletion observed by the total ozone mapping spectrometer (TOMS) experiment during winter 1992-1993. The model results also show that during winters 1986 to 1990, the formation of PSCs over Antarctica exhibits a strong interannual variation, due to temperature variability. In the colder years (1987 and 1989) the surface area of PSCs (a major factor to determine the rate of heterogeneous conversion from inactive chlorine to active chlorine) increases, and ozone concentration decreases. In the warmer years (1986 and 1988) the results are opposite. The calculated ozone interannual variation is consistent with the satellite observation (TOMS), indicating that the interannual variation of the formation of PSCs likely plays an important role for the interannual variability of the spring Antarctic ozone hole.