Global observations of C2H2 as an indicator for biomass burning from MIPAS L1B spectra
Robert Parker(1), John Remedios(1), David Moore(1), Vijay Kanawade(1) and Manasvi Panchal(1)
(1) University Of Leicester, University Road, Leicester LE1 7RH, United Kingdom
Organic compounds play a vital role in the chemistry of the troposphere, for example in ozone chemical cycles and determining the total oxidising capacity of the atmosphere. Non-methane hydrocarbons (such as alkanes and alkenes) in particular can influence the oxidising capacity of the atmosphere via their reactions with OH, ozone and NO3. The burning of vegetation, both living and dead can release large quantities of these gases into the atmosphere. Due to this, biomass burning is a major source for the injection of these trace gas organic compounds into the atmosphere.
This work details the progress in the detection and retrieval of Ethyne (C2H2) from MIPAS (Michelson Interferometer For Passive Atmospheric Sounding) infra-red spectral data in biomass burning plumes reaching the upper troposphere. These plumes are identified primarily using height-resolved carbon monoxide concentrations from the MOPITT (Measurement Of Pollution In The Troposphere) instrument. In addition, ATSR (Along Track Scanning Radiometer) Fire Maps allow identification of source regions of biomass burning. NCEP OLR data provides information on convection with Hysplit model trajectories and ECMWF wind vectors allowing the plume location and evolution to be discussed in relation to their sources.
The spectral signature of C2H2 in the biomass burning outflow is identified in MIPAS spectra for the upper troposphere through a fast automated algorithm and an optimal estimation approach is used to perform retrievals in specific regions of interest. A strong correlation between detection and retrieval results emphasises the ability of the fast detection algorithm to quickly analyse large amounts of data and produce global monthly plots.
Results show enhanced concentrations in tropical and equatorial biomass burning signatures and demonstrate that these hydrocarbons could be valuable tracers of biomass export. In addition, the strong chemical isolation inside the Asian Monsoon Anticyclone is identified and the vertical structure of this isolation is examined.