CLASSIC can be run in several different configurations, some of which require additional model inputs including:

Greenhouse gases
1. Atmospheric carbon dioxide concentration
2. Atmospheric methane concentration
Disturbrance (fire) inputs
1. Lightning frequency for fire ignition
2. Population density for fire ignition/suppresion
Competition for space between PFTs
Prognostic simulation of methane emissions
1. Dynamically-determined wetlands
2. Prescribed wetland area
Peatlands
Land use change (LUC)
Tracers

Atmospheric carbon dioxide concentration

Annual atmospheric carbon dioxide concentrations are needed for CLASS+CTEM runs. The annual values are read in from a netcdf file. If you use the NCO tool ncdump, and ncdump -hs on a properly formatted file you should yield something similar to below (only relevant sections shown here for a file with 318 years of data). Note the time units. FLAG return to this!! The chunking should be listed here

    dimensions:
        time = 318 ;
    variables:
        float mole_fraction_of_carbon_dioxide_in_air(time) ;
            mole_fraction_of_carbon_dioxide_in_air:long_name = "mole" ;
            mole_fraction_of_carbon_dioxide_in_air:units = "1.e-6" ;
            mole_fraction_of_carbon_dioxide_in_air:_FillValue = 1.e+20f ;
            mole_fraction_of_carbon_dioxide_in_air:missing_value = 1.e+20f ;
            mole_fraction_of_carbon_dioxide_in_air:cell_methods = "time: mean area: mean" ;
            mole_fraction_of_carbon_dioxide_in_air:_Storage = "contiguous" ;
            mole_fraction_of_carbon_dioxide_in_air:_Endianness = "little" ;
        double time(time) ;
            time:standard_name = "time" ;
            time:units = "**day as %Y%m%d.%f**" ;
            time:calendar = "proleptic_gregorian" ;
            time:axis = "T" ;
            time:_Storage = "contiguous" ;
            time:_Endianness = "little" ;

The variable name is not important as long as it is the only variable in the file besides time. Units expected are ppmv.

Atmospheric methane concentration

Annual atmospheric methane concentrations are needed for CLASSIC runs with biogeochemistry on (CTEM on). The annual values are read in from a netcdf file similar to CO2. The file format is the same as CO2. The variable name is not important as long as it is the only variable in the file besides time. Units expected are ppmv.

Lightning frequency for fire ignition

Daily cloud-to-ground lightning frequency is used by the disturbance subroutine for fire. The code at present is set to use daily lightning frequency. If you have mean monthly values you can interpolate them to daily values (cdo inttime is useful here). An ncdump -hs of a properly formatted file is below. Note the file is chunked for a T63 grid (128 x 64), other grids may require different chunk sizes for optimal performance. The variable name is not important as long as it is the only variable in the file besides lat ,lon, and time. Note the units of the lght_lisotd and time variables.

    netcdf lisotd_1995_2014_climtlgl_lghtng_as_ts_1700_2050_chunked {
    dimensions:
        lat = 64 ;
        time = UNLIMITED ; // (128535 currently)
        lon = 128 ;
    variables:
        double lat(lat) ;
            lat:standard_name = "latitude" ;
            lat:long_name = "latitude" ;
            lat:units = "degrees_north" ;
            lat:axis = "Y" ;
            lat:_Storage = "contiguous" ;
            lat:_Endianness = "little" ;
        float lght_lisotd(time, lat, lon) ;
            lght_lisotd:long_name = "Combined C2G (see Other_info in global attributes) Flash Rate Annual Climatology (1995-2014)" ;
            lght_lisotd:units = "**strikes km-2 yr-1**" ;
            lght_lisotd:grid_type = "gaussian" ;
            lght_lisotd:_FillValue = -1.e+38f ;
            lght_lisotd:missing_value = -1.e+38f ;
            lght_lisotd:_Storage = "chunked" ;
            lght_lisotd:_ChunkSizes = 128535, 8, 16 ;
            lght_lisotd:_Endianness = "little" ;
        double lon(lon) ;
            lon:standard_name = "longitude" ;
            lon:long_name = "longitude" ;
            lon:units = "degrees_east" ;
            lon:axis = "X" ;
            lon:_Storage = "contiguous" ;
            lon:_Endianness = "little" ;
        double time(time) ;
            time:standard_name = "time" ;
            time:units = "**day as %Y%m%d.%f**" ;
            time:calendar = "standard" ;
            time:_Storage = "chunked" ;
            time:_ChunkSizes = 128535 ;
            time:_Endianness = "little" ;

Population density for fire ignition/suppresion

Fire uses a time series of annually varying population density for fire suppression and ignition. An ncdump -hs of a properly formatted file is below. Note the file is chunked for a T63 grid (128 x 64), other grids may require different chunk sizes for optimal performance. The variable name is not important as long as it is the only variable in the file besides lat ,lon, and time.

      netcdf POPD_annual_1700_2017_T63_chunked {
      dimensions:
        lat = 64 ;
        lon = 128 ;
        time = UNLIMITED ; // (318 currently)
      variables:
        double lat(lat) ;
            lat:standard_name = "latitude" ;
            lat:long_name = "latitude" ;
            lat:units = "degrees_north" ;
            lat:axis = "Y" ;
            lat:_Storage = "contiguous" ;
            lat:_Endianness = "little" ;
        double lon(lon) ;
            lon:standard_name = "longitude" ;
            lon:long_name = "longitude" ;
            lon:units = "degrees_east" ;
            lon:axis = "X" ;
            lon:_Storage = "contiguous" ;
            lon:_Endianness = "little" ;
        float popd(time, lat, lon) ;
            popd:grid_type = "gaussian" ;
          popd:units = **"Number of people / km2"** ;
            popd:_FillValue = -9999.f ;
            popd:missing_value = -9999.f ;
            popd:_Storage = "chunked" ;
            popd:_ChunkSizes = 318, 8, 16 ;
            popd:_Endianness = "little" ;
        double time(time) ;
            time:standard_name = "time" ;
            time:units = "**day as %Y%m%d.%f**" ;
            time:calendar = "proleptic_gregorian" ;
            time:_Storage = "chunked" ;
            time:_ChunkSizes = 318 ;
            time:_Endianness = "little" ;

Climatic variables for PFT competition simulations

The PFT competition scheme (competition_scheme) uses bioclimatic variables to determine if a PFT can establish and attempt to colonize a grid cell (see competition_scheme.bioclim and competition_scheme.existence). These climatic variables are written to the model restart file for use to initialize a future run. They are also either read in from the initialization file or are determined during a model run (model switch inibioclim in the job options file).

anndefct Annual water deficit, i.e. daily values of potential evaporation that exceed precipitation accumulated over a year [mm]
annsrpls Annual water deficit, i.e. daily values of precipitation that exceed potential evaporation accumulated over a year [mm]
annpcp Annual precipitation [mm]
aridity Aridity index, ratio of potential evaporation to precipitation [ ]
defctmon Number of months in a year with water deficit, i.e. precipitation less than potential evaporation [months]
srplsmon Number of months in a year with surplus water, i.e. precipitation more than potential evaporation [months]
dry_season_length Length of consecutive dry season in months, where a dry month is defined as the month in which potential evaporation exceeds precipitation [months]
gdd5 Growing degree days above 5 C [days]
tcoldm Temperature of the coldest month [deg C]
twarmm Temperature of the warmest month [deg C]

Orographic information for dynamic wetland scheme

Eight slope based fractions are read in from the model initialization file for calculating dynamic wetland fractions. As the soil moisture in a grid cell increases above specified thresholds then the really flat portions of the grid cell are assumed to gradually turn into wetlands. The eight slope based fractions correspond to the fraction of the grid cell that have slope less than 0.025%, 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.3% and 0.35%. The numbers used by CLASSIC are based on 1/60th degree (1 minute) resolution digital elevation data. The relevant variables in the initialization file are shown below. In the file, slope is a dimension and slopefrac is a variable.

    double slope(slope) ;
      slope:long_name = "wetland slope fractions for 0.025, 0.05, 0.1, 0.15, 0.20, 0.25, 0.3 and 0.35 percent slope threshold" ;
      ...
    float slopefrac(slope, tile, lat, lon) ;
      slopefrac:_FillValue = -999.f ;
      slopefrac:units = "-" ;
      slopefrac:long_name = "Slope-based fraction for dynamic wetlands" ;

Prescribed wetland area

Daily values of wetland fraction are used for modelling methane emissions from wetlands.

      netcdf gcp-ch4_wetlands_1838-2017_t63_final_daily {
      dimensions:
              time = UNLIMITED ; // (65700 currently)
              lat = 64 ;
              lon = 128 ;
      variables:
              double Fw(time, lat, lon) ;
                      Fw:long_name = "Fraction inundated" ;
                      Fw:units = "**fraction**" ;
                      Fw:grid_type = "gaussian" ;
                      Fw:_FillValue = -9999. ;
                      Fw:missing_value = -9999. ;
                      Fw:_Storage = "chunked" ;
                      Fw:_ChunkSizes = 65700, 8, 16 ;
              double lat(lat) ;
                      lat:standard_name = "latitude" ;
                      lat:long_name = "latitude" ;
                      lat:units = "degrees_north" ;
                      lat:axis = "Y" ;
                      lat:_Storage = "contiguous" ;
              double lon(lon) ;
                      lon:standard_name = "longitude" ;
                      lon:long_name = "longitude" ;
                      lon:units = "degrees_east" ;
                      lon:axis = "X" ;
                      lon:_Storage = "contiguous" ;
              double time(time) ;
                      time:standard_name = "time" ;
                      time:long_name = "time" ;
                      time:units = "**day as %Y%m%d.%f**" ;
                      time:calendar = "365_day" ;
                      time:_Storage = "chunked" ;
                      time:_ChunkSizes = 65700 ;

Peatland variables

Peatlands are simulated following the parameterization of Wu et al. (2016) [97]. The peatland areas are specified by the ipeatland flag in the initialization file:

    float ipeatland(tile, lat, lon) ;
      ipeatland:_FillValue = -999.f ;
      ipeatland:units = "-" ;
      ipeatland:long_name = "Peatland flag: 0 = not a peatland, 1= bog, 2 = fen" ;

There are several prognostic variables that are associated with the peatland areas of the gridcell. These may be initialized to zero prior to a spinup.

    float Cmossmas(tile, lat, lon) ;
      Cmossmas:_FillValue = -999.f ;
      Cmossmas:units = "kgC/m2" ;
      Cmossmas:long_name = "C in moss biomass" ;

    float litrmsmoss(tile, lat, lon) ;
      litrmsmoss:_FillValue = -999.f ;
      litrmsmoss:units = "kgC/m2" ;
      litrmsmoss:long_name = "Moss litter mass" ;

    float dmoss(tile, lat, lon) ;
      dmoss:_FillValue = -999.f ;
      dmoss:units = "m" ;
      dmoss:long_name = "Depth of living moss" ;

If you are running a single site peatland then the peatland tile is the whole grid cell. If you are running large regions you may wish to have the peatlands as a separate tile. This is done by having an nmtest > 1 and setting up each tile appropriately.

      int nmtest(lat, lon) ;
        nmtest:_FillValue = -999 ;
        nmtest:long_name = "Number of tiles in each grid cell" ;

Land use change (LUC)

The LUC file contains an annual time series of fractional coverage of each of the CLASSIC PFTs. An ncdump -hs of a properly formatted file is below. Note the file is chunked for a T63 grid (128 x 64), other grids may require different chunk sizes for optimal performance. The variable name is not important as long as it is the only variable in the file besides lat ,lon, lev and time.

    netcdf GCP_2018_land_cover_CTEM_fractions_1700_2018_T63_chunked {
    dimensions:
        time = UNLIMITED ; // (319 currently)
        **lev = 9** ; ! This corresponds to number of biogeochemical (CTEM) PFTs.
        lat = 64 ;
        lon = 128 ;
    variables:
        float frac(time, lev, lat, lon) ;
            frac:grid_type = "gaussian" ;
        frac:units = **"fraction"** ;
            frac:_FillValue = -9999.f ;
            frac:missing_value = -9999.f ;
            frac:_Storage = "chunked" ;
            frac:_ChunkSizes = 319, 9, 8, 16 ;
            frac:_Endianness = "little" ;
        double lat(lat) ;
            lat:standard_name = "latitude" ;
            lat:long_name = "latitude" ;
            lat:units = "degrees_north" ;
            lat:axis = "Y" ;
            lat:_Storage = "contiguous" ;
            lat:_Endianness = "little" ;
        double lev(lev) ;
            lev:axis = "Z" ;
            lev:_Storage = "contiguous" ;
            lev:_Endianness = "little" ;
        double lon(lon) ;
            lon:standard_name = "longitude" ;
            lon:long_name = "longitude" ;
            lon:units = "degrees_east" ;
            lon:axis = "X" ;
            lon:_Storage = "contiguous" ;
            lon:_Endianness = "little" ;
        double time(time) ;
            time:standard_name = "time" ;
            time:units = **"day as %Y%m%d.%f"** ;
            time:calendar = "proleptic_gregorian" ;
            time:_Storage = "chunked" ;
            time:_ChunkSizes = 319 ;
            time:_Endianness = "little" ;

Tracers

In development.