HR: 0800h
AN: A51C-0777    [Abstracts]
TI: Atmospheric Burden of Some Ozone-Depleting Compounds Continues to Increase
AU: * Mondeel, D J
EM: debra.j.mondeel@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
AU: Montzka, S A
EM: stephen.a.montzka@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Butler, J H
EM: james.h.butler@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Hall, B D
EM: bradley.d.hall@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AU: Elkins, J W
EM: james.w.elkins@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80305 United States
AB: With the signing in 1987 of the Montreal Protocol on Substances that Deplete the Ozone Layer, the international community began a series of steps to reduce the emission of ozone-depleting compounds into the atmosphere. As a result of these efforts, the contribution of these gases to the atmospheric burden of ozone-depleting halogen continued to increase until 1993-94, when their collective trend reversed and began to decline (Montzka et al 1996). This decline has continued over the past decade as anticipated by models of expected emissions. Not all contributing gases, however, are decreasing in atmospheric concentration. Mixing ratios of chlorofluorocarbon-12 (CFC-12), for example, have leveled off, but the turnover is slow, owing to the long lifetime and continued release of this gas from reservoirs such as foams and older automobile air conditioners. Mixing ratios of the two major halons (H-1301 and H-1211) continue to increase, albeit much slower than in the past. H-1301, with an atmospheric lifetime of 60y, is still used worldwide for lack of a suitable replacement, although its production ceased in developed countries in 1994 and was frozen in developing countries in 2002. Growth rates of shorter-lived (20 y) H-1211, which has replacements for some uses, have dropped some, but remain positive. The atmospheric mixing ratios of hyrdrochlorofluorocarbons, the intermediate replacements for CFCs, have been increasing rapidly over the past decade, but some are showing signs of leveling off. We examine here the current and potential future contribution of all of these gases to the burden of ozone-depleting halogen in the atmosphere, focusing on why they continue to increase.
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting