We have measured gaseous methyl bromide (CH3Br) and bromoform (CHBr3) in air samples that were gathered approximately weekly from five ground-level sites: Point Barrow, Alaska; Mauna Loa Observatory and Cape Kumukahi, Hawaii; Matatula, Samoa; and Kaitorete Spit, New Zealand. Approximately 750 samples have been analyzed for CH3Br between January 1985 and October 1987 and 990 samples have been analyzed for CHBr3 between early 1984 and September 1987, all by gas chromatography/mass spectometry. Methyl bromide concentrations are typically 10-11 parts per trillion (ppt) by volume; there are no clear indications of temporal increases. Bromoform concentrations are typically 2-3 ppt, but large seasonal variations are seen at Point Barrow. -Authors

Measurements are reported of four gas‐phase, brominated organic species found in the Arctic atmosphere during March and April 1983. Volume mixing ratios for CH3Br, CH2BrCH2Br, CHBr3, and CH2Br2 were determined by GC/MS analysis from samples taken Arctic wide, including at the geographic North Pole and during a tropopause folding event over Baffin Bay near Thule, Greenland. Methyl bromide mixing ratios were reasonably constant at 11 ± 4 pptv while the other three brominated organics showed a high degree of variability. Bromoform (2 to 46 pptv) was found to be the dominant contributor to gaseous organic bromine to the Arctic troposphere at 38 ± 10% followed by CH2Br2 (3 to 60 pptv) at 29 ± 6%. Both CH3Br and CH2BrCH2Br (1 to 37 pptv) reservoirs contained less than 20% of the organically bound bromine. Stratospheric samples, taken during a tropopause folding event, showed mixing ratios for all four species at levels high enough to support a stratospheric total volume mixing ratio of 249 pptv Br (888 ngBr/SCM). Copyright 1984 by the American Geophysical Union.