DayCent5: Trace Gas Submodel

Trace Gas submodel: Sequence of steps

  1. Calculate redistribution factors for NH4, CO2, NO3 among soil layers
  2. Immobilization and Mineralization
  3. Nitrification
    1. Soil texture, temperature, pH effects on nitrification.
    2. Calculate NO3 from NH4
  4. Partition Nitrate
    1. Calculate a factor (>= 1) for the NOx flux based on recent rain events and snowpack.
    2. Calculate fractions of new NO3 that is converted to N2O and NO.
    3. Redistribute NO3 among soil layers
  5. Denitrification
    1. soil nitrate (NO3-) concentration each layer
    2. soil (N2+N2O) denitrification fluxes each layer
    3. Dentrification each layer:
      1. calculate normalized diffusivity in aggregate soil
      2. calculate water filled pore space threshold
      3. calculate CO2 correction factor when WFPS has reached threshold
      4. calculate NO3, CO2, water filled pore space effects on denitrification
      5. calculate N fluxes (N2 + N2O)
      6. NO3, water filled pore space effects on N2 : N2O
      7. calculate N2 : N2O, and N2 and N2O fluxes
    4. Reduce nitrate in soil by the amount of N2, N2O that is lost.
  6. Partition denitrification fluxes
    1. NO flux is taken from available NH4 and N2O
    2. Absorb some of NO flux into canopy according to LAI.
  7. Redistribute NH4 and NO3 among soil layers

Output Variables

Daily

Output variables for daily trace gas fluxes and pools are written to a file with the file name suffix "-tg". The file extension will be "csv" for a CSV-format file, or "nc" for a NetCDF file.

Variable   Description
CH4   Methane flux (gC m-2 day-1) .
CO2   CO2 flux from plant and microbial respiration (gC m-2 day-1).
N2   nitrogen gas flux due to denitrification (gN m-2 day-1).
N2Odnit   N2O flux due to denitrification (gN m-2 day-1).
N2Onit   N2O flux due to nitrification (gN m-2 day-1).
NO   NO flux due to denitrification and nitrification (gN m-2 day-1).
NETMIN(1-3)   Net mineralization of N, P, S (gE m-2 day-1) .
AMMONIUM(1-10)   Soil NH4 concentration by layer (gN m-2).
NITRATE(1-10)   Soil nitrate concentration by soil layer (gN m-2).
PHOSPHOR(1-10)   Soil phosphorus concentration by layer (gP m-2).
SULFUR(1-10)   Soil sulfur concentration by layer (gS m-2).

Monthly

Output variables for monthly trace gas fluxes are written to a file with the file name suffix "-mtg". The file extension will be "csv" for a CSV-format file, or "nc" for a NetCDF file.

Variable   Description
CH4   methane flux (gC m-2 month-1) .
N2   nitrogen gas flux due to denitrification (gN m-2 month-1).
N2O   N2O flux due to denitrification and nitrification (gN m-2 month-1).
NO   NO flux due to denitrification and nitrification (gN m-2 month-1).
CH4A   annual cumulative methane flux (gC m-2 year-1) .
N2A   annual cumulative nitrogen gas flux (gN m-2 year-1).
N2OA   annual cumulative N2O flux due to denitrification and nitrification (gN m-2 year-1).
NOA   annual cumulative NO flux (gN m-2 year-1).

References

The following papers are the main sources for the N algorithms in DayCent5.

Del Grosso, S. J.; Parton, W. J.; Mosier, A. R.; Ojima, D. S.; Kulmala, A. E.; Phongpan, S. 2000. General model for N2O and N2 gas emissions from soils due to denitrification. Global Biogeochem. Cycles 14, No. 4, 1045-1060.

Parton, W. J.; Holland, E. A.; Del Grosso, S. J.; Hartman, M. D.; Martin, R. E.; Mosier, A. R.; Ojima, D. S.; Schimel, D. S. 2001. Generalized model for NOx and N2O emissions from soils. J. Geophys. Res. Vol. 106 , No. D15 , p. 17,403-17,419.

See Also

DayCent5 Overview