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          Institute: MPI für Chemie     Collection: Publikationen MPI für Chemie     Display Documents

ID: 18287.0, MPI für Chemie / Publikationen MPI für Chemie
Budgets of O3 and CO in the upper troposphere: CARIBIC passenger aircraft results 1997-2001
Authors:Zahn, A.; Brenninkmeijer, C. A. M.; Asman, W. A. H.; Crutzen, P. J.; Heinrich, G.; Fischer, H.; Cuijpers, J. W. M.; van Velthoven, P. F. J.
Date of Publication (YYYY-MM-DD):2002-09
Title of Journal:Journal of Geophysical Research
Journal Abbrev.:J. Geophys. Res.
Issue / Number:D17
Sequence Number of Article:4337
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:In situ measurements of ozone (O-3) and carbon monoxide (CO) were conducted using a passenger aircraft during 47 flights (November 1997 to April 2001) between Germany and the Indian Ocean region at 10-11 km altitude, project Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrument Container (CARIBIC). Here, emphasis is on a better understanding of the budgets of O-3 and CO in the middle and upper northern hemispheric (NH) troposphere. Latitudinal and seasonal variations of the mean values and the local variability of O-3 and CO are assessed. CO is moreover applied as tracer of polluted (surface) air, that is, as a measure of O-3 precursors. This enables us to assign positive or negative O-3-CO correlations and their slopes alpha=dO(3)/dCO to O-3 produced by photochemistry or to O-3 imported from the stratosphere. In the tropics, photochemical O-3 production clearly dominates all year round, with mean O-3-CO slopes of 0.45-0.53 in spring/summer and 0.20-0.27 in autumn/winter. Over the Arabian Sea and the Middle East, high annual net O-3 production rates in the troposphere of 17.6x10(10) O-3 molecules cm(-2) s(-1) are estimated. In the extratropics, the well-documented springtime O-3 maximum emerged in the CARIBIC data set. Stratospheric O-3 influx and photochemical O-3 production contribute equally to this spring maximum. In summer, photochemical O-3 formation clearly dominates, in winter, per contra, stratospheric O-3 influx clearly dominates. In the extratropics, CO shows a sine seasonal variation between similar to81 ppbv in September and similar to111 ppbv in March, being delayed by similar to5 weeks compared to ground-based background monitoring stations. In the tropics, however, no significant seasonal variations of CO were observed, mainly because of occasional high CO periods such as those associated with the 1997 Indonesian forest fires or the outflow of the Intertropical Convergence Zone, which pumps in summer immense amounts of pollutants emitted in South Asia (India, Bangladesh, Indochina) to the 10-11 km altitude range surveyed during CARIBIC.
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Chemie/Chemie der Atmosphäre
External Affiliations:Forschungszentrum Karlsruhe, Inst Meteorol & Climate Res, POB; 3640, D-76021 Karlsruhe, Germany; Royal Netherlands Meteorol Inst, NL-3730 AE De Bilt, Netherlands
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