Photochemical rates are computed using the Tropspheric Ultraviolet and Visible (TUV) Radiation Model. 

https://www2.acom.ucar.edu/modeling/tropospheric-ultraviolet-and-visible-tuv-radiation-model

Source code location: MICM_Chemistry/src/tuv/tuv_photolysis.F90

Given a column of environment conditions, solar zenith angle, and surface albedo, a column of photolysis rates are produced.

For the time being only clear sky conditions are considered (no cloud or aerosol inputs).

Another scheme is used to map the column of TUV photolysis rates to the rates needed to solve the chemistry in the grid cell of interest.

Inputs

• solar zenith angle
• surface albedo
• column of mid-point layer pressures
• column of layer interface pressures
• column of mid-point layer altitudes
• column of mid-point layer O2 VMR
• column of mid-point layer O3 VMR
• column of mid-point layer SO2 VMR
• column of mid-point layer NO2 VMR

Output

• column of mid-point layer photochemical rates

Cross Sections and Quantum Yields

Metadata

!> \section arg_table_tuv_photolysis_run Argument Table

!! | local_name | standard_name                         | long_name                      | units     | rank | type      | kind      | intent | optional |

!! |------------|---------------------------------------|--------------------------------|-----------|------|-----------|-----------|--------|----------|

!! | zenith     | solar_zenith                          | solar zenith angle             | degrees   |    0 | real      | kind_phys | in     | F        |

!! | albedo     | surface_albedo                        | surface albedo                 | none      |    0 | real      | kind_phys | in     | F        |

!! | press_mid  | layer_pressure                        | mid-point layer pressure       | Pa        |    1 | real      | kind_phys | in     | F        |

!! | press_int  | layer_interface_pressure              | layer interface pressure       | Pa        |    1 | real      | kind_phys | in     | F        |

!! | alt        | layer_altitude                        | mid-point layer altitude       | km        |    1 | real      | kind_phys | in     | F        |

!! | temp       | layer_temperature                     | mid-point layer temperature    | K         |    1 | real      | kind_phys | in     | F        |

!! | o2vmr      | O2_vmr_col                            | O2 volume mixing ratio column  | mole/mole |    1 | real      | kind_phys | in     | F        |

!! | o3vmr      | O3_vmr_col                            | O3 volume mixing ratio column  | mole/mole |    1 | real      | kind_phys | in     | F        |

!! | so2vmr     | SO2_vmr_col                           | SO2 volume mixing ratio column | mole/mole |    1 | real      | kind_phys | in     | F        |

!! | no2vmr     | NO2_vmr_col                           | NO2 volume mixing ratio column | mole/mole |    1 | real      | kind_phys | in     | F        |

!! | prates     | photolysis_rates_col                  | photolysis rates column        | s-1       |    2 | real      | kind_phys | out    | F        |

!! | o3totcol   | ozone_column_density                  | total ozone column density     | DU        |    0 | real      | kind_phys | out    | F        |

!! | errmsg     | ccpp_error_message                    | CCPP error message             | none      |    0 | character | len=512   | out    | F        |

!! | errflg     | ccpp_error_flag                       | CCPP error flag                | flag      |    0 | integer   |           | out    | F        |

!!