THE CARIBIC BOEING-767 FLIGHTS: HALOCARBON OBSERVATIONS

M. Maiss (1), C.A.M. Brenninkmeijer (1), A. Jordan (2), R. Borchers (2), D. Oram (3), H. Cuijpers (4), P. van Velthoven (4), and P.J. Crutzen (1)

(1) MPI für Chemie, Mainz, maiss@mpch-mainz.mpg.de, fax +49-6131-3305436,
(2) MPAE, Katlenburg-Lindau,
(3) UEA, Norwich,
(4) KNMI, De Bilt

Within the European project CARIBIC whole air samples are collected onboard a LTU Boeing 767 passenger aircraft routinely on return flights to Germany from destinations in the Indian Ocean region (Male, Colombo). Samples are analyzed for CH4, CO, N2O, CO2, SF6 and all major organic chlorine and bromine species. This data represent the most extensive suite of halogenated organic trace gases measured simultaneously on transects from the upper tropical troposphere to the lower mid-latitudinal stratosphere. These halocarbon measurements account for nearly 100% of the total amount of organic chlorine and bromine possibly entering the stratosphere in tropical regions. Our tropical observations frequently show near surface air masses at flight level with characteristic fingerprints of anthropogenic polution (solvents, toluol), biomass burning (CO, CH3Cl, CH3Br), rice paddy emmisions (CH4, CHCl3) or oceanic emissions (CH2Br2, CHBr3) identified and verified by respective trace gas correlations and back-trajectories. Of special interest are the methyl-halide mixing ratios with generally enhanced tropical levels. Due to unexpected high bromoform contributions the bromine loading of the tropical troposphere is sometimes doubled with respect to typical mid-latitudinal observations.

Notes

Oral presentation at the EGS - XXIV General Assembly, The Hague, The Netherlands, 19-23 April, 1999
in: OA26, Recent developments and new concepts in tropospheric chemistry