MOTIVATING SCIENCE ISSUES

There are a number of intriguing science issues relating to AICI; as examples:

Ozone depletion as observed in the Arctic and Antarctic

See for example Bottenheim et al., Atmos Environ., 36, 2535, 2002. One issue is the role of snow and sea ice surfaces in liberating halogens that destroy ozone. It is known that O3 can be destroyed in snowpacks, e.g. as shown in Figure 1 below, taken from Albert et al., Atmos. Environ., 36, 2779, 2002.Another major question is the role of frost flowers (cf. Rankin et al. Geophys.Res.Lett., 27, 3469-3472, 2000.See Figure 2) in liberating photoactive halogen compounds that destroy O3. A useful tool in this regard is satellite retrievals of column BrO, as shown in Figure 3.

Snowpack photochemistry

See for example Honrath et al., JGR, 105, 24183, 2000; Snowpack photochemistry results in production of a wide variety of photolytcally active species, such as NOx, Br2, HONO, and HCHO. This can have a very significant impact on atmospheric chemistry over sunlit snowpacks. For example, Davis et al. (Geophysical Research Letters, 28 (19), 3625-3628, 2001) observe NOx concentrations at South Pole high enough to result in net O3 production.

Impacts on Toxic Pollutants

AICI interactions induce gas phase processes that transform toxic pollutants, and deposit the products to the snowpack (cf. Lu et al. Geophys. Res. Lett., 28, 3219-3222, 2001)