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Input Files

Gas Chemistry Input File

The YAML input file for atmospheric chemistry consists of five sections:

  • environmental_conditions: pressure and temperature of individual cells.
  • initial_state: initial species concentrations within the cells.
  • reactions: list of reactions with rate parameters and reaction type.
  • constant_species: species that are part of the reaction mechanism but are assumed constant in time.
    • E.g., invariant species.
  • species: list of species names.

For example, given the toy reaction \(A \rightarrow B\), simulation with N cells, one reaction, and three species, we have

NCAR-version: v1.0
environmental_conditions:
  pressure:
    evolving: false
    initial_value: [P1, ..., PN]
    units: Pa
  temperature:
    evolving: false
    initial_value: [T1, ..., TN]
    units: K
initial_state:
  A:
    initial_value: [A1, .., AN]
    units: mol m-3
  M:
    initial_value: [M1, .., MN]
    units: mol m-3
reactions:
- coefficients:
  products:
    B: 1.0
  reactants:
    A: 1.0
  type: ARRHENIUS
constant_species:
- description: tracer-CONSTANT
  name: M
species:
- description: A
  name: A
- description: B
  name: B

A description of the reaction types currently implemented in TChem-atm is presented in Methodology section. In addition, a set of examples of input files is presented under /src/examples/runs/atmopheric_chemistry.

Gas-Aerosol Chemistry Input File

To execute a gas-aerosol case in TChem-atm, one needs an input file with the aerosol mechanisms, aerofile, and a file where scenario particle information is given, inputfile_particles. The aerosol mechanism utilizes a YAML file and follows to the CAMP format. The scenario particle information follows this format:

particles:
  initial_state:
    species_name_1: 
      initial_value: [1.0e-8]
    species_name_2: 
      initial_value: [1.4e-2]
  num_concentration:
   initial_value: [1.3e6]
In this structure, species_name_1 denotes the initial concentration of species 1 within a single particle. It's important to note that the initial composition for species 1 is consistent across all particles.

Additionally, to incorporate gas-phase reactions into the simulation, a gas reaction mechanism can be seamlessly integrated into the gas-aerosol case.