Linear Chemistry Module

The Linear Chemistry Module (LCM) is based on the initial work of Henne et al. who developed the FLEXPART-CTM model from FLEXPART 8, and was first described in Groot Zwaaftink et al.. This model was an extension of the domain-filling capability of FLEXPART and added the possibility to initialise particles’ mixing ratio from pre-defined fields and to account for the influence of surface fluxes and simple linear chemistry on the particles’ mass.

How to run LCM

To run the LCM the following OPTIONS files are used and need to be edited (see also the Appendix for example OPTIONS files):

  1. COMMAND: choose the following options:

    • LDIRECT= 1 (forward simulation)
    • MDOMAINFILL = 1 (domain-filling mode)
    • IND_SOURCE = 1 (releases units of mass)
    • IND_RECEPTOR = 1 (receptor units of mass)
    • LCMOUTPUT = 1 (uses the LCM initialization and output formats)

  2. RELEASES: specify the following:

    • NSPEC: number of species including the mandatory species AIRTRACER
    • SPECNUM_REL: species number in the directory SPECIES (note AIRTRACER must be the first species)
    • LON1: left longitude of release box for global domain
    • LON2: right longitude of release box for global domain
    • LAT1: lower latitude of release box for global domain
    • LAT2: upper latitude of release box for global domain
    • PARTS: total number of particles to be used

  3. INITCONC: specifies input for initializing the mixing ratios

  4. OUTGRID: specifies the domain and vertical levels for the gridded output

  5. REAGENTS (optional): specifies chemical reagents for reactions (the corresponding rate constants are given in the SPECIES files)

  6. RECEPTORS (optional): specifies the locations and times of receptors where mixing ratios should be output.

  7. SATELLITES (optional): specifies paths and input file names of satellite retrievals for which mixing ratios should be output. Input files need to be generated from a satellite pre-processor, prep_satellite, and can be created using software obtainable from flexinvertplus.