A. Douglass et al., A 3D SIMULATION OF THE EARLY WINTER DISTRIBUTION OF REACTIVE CHLORINEIN THE NORTH POLAR VORTEX, Geophysical research letters, 20(12), 1993, pp. 1271-1274
Early in December 1991, high values of ClO are seen by the Microwave L
imb Sounder (MLS) on the Upper Atmosphere Research Satellite at latitu
des south of areas of temperatures cold enough to form polar stratosph
eric clouds (PSC's). A three dimensional simulation shows that the het
erogeneous conversion of chlorine reservoirs to reactive chlorine on t
he surfaces of PSC's (processing) takes place at high latitudes. Often
the ''processed'' air must be transported to lower latitudes, where t
he reactive chlorine is photochemically converted to ClO, to be observ
ed by MLS. In this simulation, one incidence of cold temperatures is a
ssociated with an anticyclone, and a second with a cyclone. The transp
ort of processed air associated with the anticyclone is marked by shea
ring; a decrease in the maximum of the processed air is accompanied by
growth of the area influenced by the processing. In contrast, the air
processed in the cyclonic event spreads more slowly. This shows that
transport and shearing is a crucial element to the evolution of reacti
ve chlorine associated with a processing event. In particular, transpo
rt and shearing, as well as photochemical processes, can cause variati
ons in observed ClO.