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Unexplained enhancements of CH 3 Br in the Arctic and sub‐Arctic lower troposphere during TOPSE spring 2000
Author(s) -
Wingenter Oliver W.,
Sive Barkley C.,
Blake Donald R.,
Rowland F. Sherwood,
Ridley Brian A.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018159
Subject(s) - troposphere , stratosphere , ozone depletion , bromine , bromide , arctic , atmospheric sciences , ozone , environmental science , atmosphere (unit) , ozone layer , mixing ratio , the arctic , climatology , environmental chemistry , chemistry , oceanography , meteorology , geology , physics , organic chemistry
Elevated concentrations of methyl bromide (CH 3 Br) were observed in the Arctic atmospheric boundary layer (BL) during periods of widespread BL ozone (O 3 ) depletion episodes (ODEs: O 3 mixing ratios < 20 × 10 −9 or parts per billion by volume, ppbv) particularly during major ODEs (MODES: O 3 < 4 ppbv). No other organic gases measured during TOPSE (Tropospheric Ozone Production about the Spring Equinox) exhibited anti‐correlations with O 3 during these ODEs. Methyl bromide has both natural and anthropogenic sources and contributes ∼ half of the bromine (Br) to the stratosphere, where it can catalytically destroy O 3 . Several known CH 3 Br sources are evaluated, but the current knowledge cannot explain the observed enhancements. If the mechanism is direct gas‐phase photochemical production, a significant portion of the unknown CH 3 Br source may be found.