Local and global effects on ozone from Titan rocket exhaust and deorbiting spacecraft debris

Both the launching and deorbiting of spacecraft introduce foreign material directly into the stratosphere, a region of the atmosphere extending from around 12 to 50km above the earth`s surface. Launching of Titan and similar solid rocket motors adds to the stratospheric inorganic chlorine burden through emissions of HCl, atomic (Cl) and molecular (CL{sub 2}) directly into the stratosphere. Before the exhaust plume disperses, plume concentrations of these species are orders of magnitude above the background values (Denison et al, 1994). Dispersed through the stratosphere over the globe, however, the additional Cl burden is small compared to the background for currently envisioned launch frequencies. Inorganic chlorine is cleared from the atmosphere by wet deposition of HCl in rain after transport processes return air from the stratosphere to the troposphere, with an overall lifetime of a few years. After several year,a continuing fixed injection rate will produce a chlorine enhancement that reaches a steady state, balanced with loss via rainout. We report here on calculations in models in both two- and three dimensions that address three questions in rocket/spacecraft/stratospheric interactions. We have attempted to represent the early evolution (1-50 hours) of a vertical plume in the stratosphere with a Langrangian three- dimensional transport model driven by horizontal winds from a data- assimilating general circulation model. We have also conducted global calculations of the potential steady state effects of Cl injection from a specified rate of continuous launches in a current two- dimensional model of the stratosphere including all known important ozone production and loss processes. And, we have calculated the effect of increasing the steady state particulate surface area density in the stratosphere resulting from particle formation from satellite destruction on reentry