Measurements of halogenated organic compounds near the tropical tropopause
- National Center for Atmospheric Research, Boulder, CO (United States)
- NASA Ames Research Center, Moffett Field, CA (United States)
- NOAA Aeronomy Lab., Boulder, CO (United States)
The amount of organic chlorine and bromine entering the stratosphere have a direct influence on the magnitude of chlorine and bromine catalyzed ozone losses. Twelve organic chlorine species and five organic bromine species were measured from 12 samples collected near the tropopause between 23.8[degrees]N and 25.3[degrees]N during AASE II. The average mixing ratios of total organic chlorine and total organic bromine were 3.50 [+-] 0.06 ppbv and 21.1 [+-] 0.8 pptv, respectively. CH[sub 3]Cl represented 15.1% of the total organic chlorine, with CFC 11 (CCl[sub 3]F) and CFC 12 (CCl[sub 2]F[sub 2]) accounting for 22.6% and 28.2%, respectively, with the remaining 34.1% primarily from CCl[sub 4], CH[sub 3]CCl[sub 3], and CFC 113 (CCl[sub 2]FCClF[sub 2]). CH[sub 3]Br represented 54% of the total organic bromine. The 95% confidence intervals of the mixing ratios of all but four of the individual compounds were within the range observed in low and mid-latitude mid-troposphere samples. The four compounds with significantly lower mixing ratios at the tropopause were CHCl[sub 3], CH[sub 2]Cl[sub 2], CH[sub 2]Br[sub 2], and CH[sub 3]CCl[sub 3]. The lower mixing ratios may be due to entrainment of southern hemisphere air during vertical transport in the tropical region and/or to exchange of air across the tropopause between the lower stratosphere and upper troposphere. 14 refs., 3 tabs.
- OSTI ID:
- 5140357
- Journal Information:
- Geophysical Research Letters (American Geophysical Union); (United States), Vol. 20:22; ISSN 0094-8276
- Country of Publication:
- United States
- Language:
- English
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