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

ID: 18271.0, MPI für Chemie / Publikationen MPI für Chemie
Are CH2O measurements in the marine boundary layer suitable for testing the current understanding of CH4 photooxidation?: A model study
Authors:Wagner, V.; von Glasow, R.; Fischer, H.; Crutzen, P. J.
Date of Publication (YYYY-MM-DD):2002-02-16
Title of Journal:Journal of Geophysical Research
Journal Abbrev.:J. Geophys. Res.
Issue / Number:D3
Sequence Number of Article:4029
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:[1] On the basis of a data set collected during the Indian Ocean Experiment (INDOEX) campaign 1999, we investigated the formaldehyde (CH2O) budget in the southern Indian Ocean (SIO). With a photochemical box model we simulated the contribution of methane and nonmethane volatile organic compounds to the CH2O budget. To identify the reactions and model constraints that introduce the largest uncertainties in the modeled CH2O concentration, we carried out a local sensitivity analysis. Furthermore, a Monte Carlo method was used to assess the global error of the model predictions. According to this analysis the 2 uncertainty in the modeled CH2O concentration is 49%. The deviation between observed (200 +/- 70 parts per trillion by volume (pptv) (2sigma)) and modeled (224 +/- 110 pptv (2sigma)) daily mean CH2O concentration is 12%. However, the combined errors of model and measurement are such that deviations as large as 65% are not significant at the 2 level. Beyond the "standard'' photochemistry we analyzed the impact of halogen and aerosol chemistry on the CH2O concentration and investigated the vertical distribution of CH2O in the marine boundary layer (MBL). Calculations with the Model of Chemistry Considering Aerosols indicate that, based on the current understanding, halogen chemistry and aerosol chemistry have no significant impact on the CH2O concentration under conditions encountered in the SIO. However, a detailed investigation including meteorological effects such as precipitation scavenging and convection reveals an uncertainty in state-of- the-art model predictions for CH2O in the MBL that is too large for a meaningful test of the current understanding of CH4 photooxidation.
Free Keywords:formaldehyde; CH2O; HCHO; troposphere; marine boundary layer; budget
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Chemie/Chemie der Atmosphäre
External Affiliations:Univ Leeds, Sch Chem, Leeds LS2 9JT, W Yorkshire, England
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