Abstract
Abstract. Near global upper tropospheric concentrations of carbon monoxide (CO), ethane (C2H6) and ethyne (C2H2) from ACE (Atmospheric Chemistry Experiment) Fourier transform spectrometer on board the Canadian satellite SCISAT-1 are presented and compared with the output from the Chemical Transport Model (CTM) GEOS-Chem. The retrievals of ethane and ethyne from ACE have been improved for this paper by using new sets of microwindows compared with those for previous versions of ACE data. With the improved ethyne retrieval we have been able to produce a near global upper tropospheric distribution of C2H2 from space. Carbon monoxide, ethane and ethyne concentrations retrieved using ACE spectra show the expected seasonality linked to variations in the anthropogenic emissions and destruction rates as well as seasonal biomass burning activity. The GEOS-Chem model was run using the dicarbonyl chemistry suite, an extended chemical mechanism in which ethyne is treated explicitly. Seasonal cycles observed from satellite data are well reproduced by the model output, however the simulated CO concentrations are found to be systematically biased low over the Northern Hemisphere. An average negative global mean bias of 12% and 7% of the model relative to the satellite observations has been found for CO and C2H6 respectively and a positive global mean bias of 1% has been found for C2H2. ACE data are compared for validation purposes with MkIV spectrometer data and Global Tropospheric Experiment (GTE) TRACE-A campaign data showing good agreement with all of them.
Highlights
The Volatile Organic Compounds (VOCs) ethane (C2H6) and ethyne (C2H2) are two of the most important tropospheric organic trace gases
Ethyne may act as a precursor of Secondary Organic Aerosols (SOA) through the formation of glyoxal, a by-product from of its oxidation by OH (Volkamer et al, 2009)
The ACE-FTS (Atmospheric Chemistry Experiment-Fourier Transform Spectrometer) is the main instrument on board the Canadian satellite SCISAT-1 launched by NASA in August 2003
Summary
The Volatile Organic Compounds (VOCs) ethane (C2H6) and ethyne (C2H2) are two of the most important tropospheric organic trace gases. Ethyne has been retrieved extensively from space by ACE, for example as reported by Park et al (2008) in the Asian monsoon anticyclone and by MIPAS (Glatthor et al, 2007; Parker et al, 2010) some more limited retrievals were made previously by ATMOS for both ethane and ethyne (Irion et al, 2002) Concentrations of these molecules have been retrieved using data from the ACE Fourier Transform Spectrometer (FTS) and compared with aircraft data from the GTE (Global Tropospheric Experiment) TRACE-A (Transport and Atmospheric Chemistry near the Equator-Atlantic) field mission (Blake et al, 1996; Chatfield et al, 1998; Fishman et al, 1996) and from the MkIV balloon-borne FTIR flights near Fort Sumner (Toon, 1991). In section five the data from ACE and GEOS-Chem are analyzed, discussed and compared; the final section is a conclusion
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