ElementalCarbon

{
  "reference": {
    "citation": "Fierce, L., et al. (2023) ACP 23, 4327–4339. https://doi.org/10.5194/acp-23-4327-2023 — default particle density. Migrated from Aerosol.jl src/elemental_carbon.jl `ElementalCarbon` (esm-hv0).",
    "notes": "source_ref: Aerosol.jl@main:src/elemental_carbon.jl:13\n\nUpstream `ElementalCarbon` is an MTK `@component` with four parameters (ρ, d_p, T, P) and two variables: EC (ODE state, D(EC)~0) and v_placeholder (algebraic, v_placeholder~ρ*d_p*T*P*1e-20). The sole purpose of v_placeholder is to prevent MTK's dead-code elimination from pruning the four parameters that are not referenced in the D(EC)~0 equation. There is no physical content in v_placeholder.\n\nESM representation:\n- EC is a `state` variable with ODE D(EC)/dt = 0 (EC conserved, constant at its initial condition).\n- ρ, d_p, T, P are `parameter` types. Parameters in ESM are preserved by definition and do not require a placeholder equation, so v_placeholder is deliberately omitted.\n- The constant `zero = 0 ppb/s` from the upstream source is folded into the literal 0 on the RHS of the D(EC) equation.\n\nMigration tracker note: features list 'equations (with DataInterpolations.LinearInterpolation)' with blocking_gap 'none (data is constants in-place)'. This means the relevant data (particle density, diameter defaults) is given as hardcoded scalar constants in the source, so no interpolation table is needed in the ESM.\n\nTest strategy: since D(EC)/dt = 0, EC(t) equals its initial condition for all t. Tests verify this conservation law at multiple times and initial conditions. The parameters ρ, d_p, T, P do not appear in any equation and cannot affect EC — this invariance is tested in parameter_variation."
  },
  "tolerance": {
    "rel": 1e-09
  },
  "variables": {
    "EC": {
      "type": "unknown",
      "units": "ppb",
      "description": "Elemental Carbon concentration. Conserved tracer: D(EC)/dt = 0, so EC is constant at its initial condition. Coupled models (e.g. NEI emissions) can add source/sink terms via the coupling mechanism."
    },
    "ρ": {
      "type": "parameter",
      "units": "kg/m^3",
      "default": 1.1,
      "description": "Particle density. Default from Fierce et al. (2023), DOI:10.5194/acp-23-4327-2023."
    },
    "d_p": {
      "type": "parameter",
      "units": "m",
      "default": 8e-07,
      "description": "Particle diameter."
    },
    "T": {
      "type": "parameter",
      "units": "K",
      "default": 298.15,
      "description": "Temperature."
    },
    "P": {
      "type": "parameter",
      "units": "Pa",
      "default": 101325.0,
      "description": "Pressure."
    }
  },
  "equations": [
    {
      "lhs": {
        "op": "D",
        "wrt": "t",
        "args": [
          "EC"
        ]
      },
      "rhs": 0
    }
  ],
  "tests": [
    {
      "id": "default_ic_conserved",
      "description": "Default initial condition EC = 1.0 ppb. Since D(EC)/dt = 0, EC must equal 1.0 ppb at all times. Checks t = 0, 50, 100 s.",
      "time_span": {
        "start": 0.0,
        "end": 100.0
      },
      "initial_conditions": {
        "EC": 1.0
      },
      "assertions": [
        {
          "variable": "EC",
          "time": 0.0,
          "expected": 1.0,
          "tolerance": {
            "rel": 1e-09
          }
        },
        {
          "variable": "EC",
          "time": 50.0,
          "expected": 1.0,
          "tolerance": {
            "rel": 1e-09
          }
        },
        {
          "variable": "EC",
          "time": 100.0,
          "expected": 1.0,
          "tolerance": {
            "rel": 1e-09
          }
        }
      ]
    },
    {
      "id": "custom_ic_conserved",
      "description": "Custom initial condition EC = 5.0 ppb. EC must remain 5.0 ppb for all t.",
      "time_span": {
        "start": 0.0,
        "end": 100.0
      },
      "initial_conditions": {
        "EC": 5.0
      },
      "assertions": [
        {
          "variable": "EC",
          "time": 0.0,
          "expected": 5.0,
          "tolerance": {
            "rel": 1e-09
          }
        },
        {
          "variable": "EC",
          "time": 100.0,
          "expected": 5.0,
          "tolerance": {
            "rel": 1e-09
          }
        }
      ]
    },
    {
      "id": "parameter_variation_no_ec_effect",
      "description": "Varying particle properties (ρ, d_p, T, P) cannot affect EC because none appear in the D(EC)/dt = 0 equation. EC = 2.0 ppb with non-default parameters must remain 2.0 ppb.",
      "time_span": {
        "start": 0.0,
        "end": 100.0
      },
      "initial_conditions": {
        "EC": 2.0
      },
      "parameter_overrides": {
        "ρ": 2.0,
        "d_p": 5e-07,
        "T": 280.0,
        "P": 90000.0
      },
      "assertions": [
        {
          "variable": "EC",
          "time": 0.0,
          "expected": 2.0,
          "tolerance": {
            "rel": 1e-09
          }
        },
        {
          "variable": "EC",
          "time": 100.0,
          "expected": 2.0,
          "tolerance": {
            "rel": 1e-09
          }
        }
      ]
    }
  ],
  "analyses": [
    {
      "id": "ec_time_series",
      "description": "Time series of EC concentration from t = 0 to 3600 s (1 hour) with default initial condition EC = 1.0 ppb. Because D(EC)/dt = 0, the output is a flat line — this example illustrates the conserved-tracer behavior and serves as a reference for models that couple an emission source to ElementalCarbon.",
      "initial_state": {
        "EC": 1.0
      },
      "parameters": {
        "ρ": 1.1,
        "d_p": 8e-07,
        "T": 298.15,
        "P": 101325.0
      },
      "time_span": {
        "start": 0.0,
        "end": 3600.0
      },
      "plots": [
        {
          "id": "ec_vs_time",
          "type": "line",
          "description": "Elemental Carbon concentration vs time. Flat at 1.0 ppb, confirming the conserved-tracer equation D(EC)/dt = 0.",
          "x": {
            "variable": "t",
            "label": "Time (s)"
          },
          "y": {
            "variable": "EC",
            "label": "EC (ppb)"
          }
        }
      ]
    }
  ]
}