Premium
Timescales in atmospheric chemistry: CH 3 Br, the ocean, and ozone depletion potentials
Author(s) -
Prather Michael J.
Publication year - 1997
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/97gb01055
Subject(s) - stratosphere , ozone depletion , biogeochemical cycle , ozone layer , bromine , ozone , atmospheric sciences , troposphere , atmosphere (unit) , atmospheric chemistry , bromide , chemistry , southern hemisphere , environmental science , climatology , environmental chemistry , meteorology , physics , geology , inorganic chemistry , organic chemistry
Methyl bromide (CH 3 Br) supplies about half of the chemically active bromine (Br y ) in the stratosphere. Efforts to control Br y ‐catalyzed ozone depletion by phasing out, for example, agricultural use of CH 3 Br may be thwarted by a lack of understanding of how the varied biogeochemical processes interact as a coupled system: in addition to the chemical industry, large natural sources come from the ocean; and losses occur in the atmosphere, ocean, and soils. A simplified one‐dimensional stratosphere‐troposphere‐ocean model for {CH 3 Br, Br y } that fits current understanding of sources and sinks is analyzed in terms of natural modes. Surface and ocean sources have effectively different steady state lifetimes (1.0 and 0.5 years, respectively), but the natural‐mode decay times of the system (1.8 years for CH 3 Br and 4.5 years for stratospheric Br y ) do not depend on the location of sources. The cumulative ozone depletion resulting from a single atmospheric release of CH 3 Br integrates over the consequent slow rise and fall of Br y in the lower stratosphere. Thus, in spite of the 1‐year lifetime of CH 3 Br, only half of the anticipated ozone recovery occurs in the first 7 years.