BurningIndex

Burning Index (BI) from the National Fire Danger Rating System (NFDRS). BI is numerically equivalent to 10 times the predicted flame length in feet. BI = 3.01 × (SC × ERC)^0.46, where SC is the spread component (m/s) and ERC is the energy release component (dimensionless). From Cohen & Deeming (1985), page 12.

.esm schema: 1.0.0
Source: components/wildland_fire/nfdrs/burning_index.esm

Description

Reference

source_ref: WildlandFire.jl@126976f2508ceacca6c486b21ae6da5b168c6f46:src/nfdrs.jl:1231 The Burning Index (BI) is calculated as BI = 3.01 × (SC × ERC)^0.46, where SC (spread component) is converted from m/s to ft/min for the calculation. The max(0.0, …) ensures non-negative input to the power function. When fuels_wet > 0.5, BI is set to 0.0.

Parameters

Name	Units	Default	Description
`ms_to_fpm`	`1`	`196.8504`	Numerical conversion: m/s to ft/min (dimensionless)
`fuels_wet`	`1`	`0`	Flag: 1 if fuels wet or snow-covered (dimensionless)
`ERC`	`1`		Energy release component (dimensionless)
`SC`	`m/s`		Spread component
`V_ref`	`m/s`	`1`	Reference velocity for non-dimensionalization

Observed

Name	Units	Default	Description
`BI`	`1`		Burning index (dimensionless)

Observed expressions

$$ BI = \mathrm{ifelse}\left(\mathrm{<}\left(0.5, fuels_{wet}\right), 0, 3.01 \cdot \mathrm{max}\left(0, \frac{ms_{to\,fpm} \cdot ERC \cdot SC}{V_{ref}}\right)^{0.46}\right) $$

Burning index (dimensionless)

Analyses

default_burning_index

Default BurningIndex run with typical fire danger conditions

Time span: 0 → 1

Raw .esm

Raw .esm JSON (this component)

{
  "tests": [
    {
      "parameter_overrides": {
        "fuels_wet": 0,
        "ERC": 20,
        "SC": 0.254
      },
      "time_span": {
        "start": 0,
        "end": 1
      },
      "id": "BurningIndex_normal_conditions",
      "assertions": [
        {
          "expected": 72.2,
          "time": 1,
          "variable": "BI",
          "tolerance": {
            "abs": 0.1
          }
        }
      ],
      "description": "Test BI = 3.01 * (SC_fpm * ERC)^0.46 with SC=0.254 m/s (= 50 ft/min), ERC=20: BI = 3.01 * 1000^0.46 ≈ 72.20."
    },
    {
      "parameter_overrides": {
        "fuels_wet": 1,
        "ERC": 20,
        "SC": 0.254
      },
      "time_span": {
        "start": 0,
        "end": 1
      },
      "id": "BurningIndex_wet_conditions",
      "assertions": [
        {
          "expected": 0,
          "time": 1,
          "variable": "BI",
          "tolerance": {
            "abs": 0.001
          }
        }
      ],
      "description": "Test BI = 0 when fuels_wet = 1"
    }
  ],
  "variables": {
    "ms_to_fpm": {
      "units": "1",
      "default": 196.8504,
      "type": "parameter",
      "description": "Numerical conversion: m/s to ft/min (dimensionless)"
    },
    "fuels_wet": {
      "units": "1",
      "default": 0,
      "type": "parameter",
      "description": "Flag: 1 if fuels wet or snow-covered (dimensionless)"
    },
    "ERC": {
      "units": "1",
      "type": "parameter",
      "description": "Energy release component (dimensionless)"
    },
    "SC": {
      "units": "m/s",
      "type": "parameter",
      "description": "Spread component"
    },
    "V_ref": {
      "units": "m/s",
      "default": 1,
      "type": "parameter",
      "description": "Reference velocity for non-dimensionalization"
    },
    "BI": {
      "units": "1",
      "type": "unknown",
      "description": "Burning index (dimensionless)"
    }
  },
  "reference": {
    "notes": "source_ref: WildlandFire.jl@126976f2508ceacca6c486b21ae6da5b168c6f46:src/nfdrs.jl:1231\nThe Burning Index (BI) is calculated as BI = 3.01 × (SC × ERC)^0.46, where SC (spread component) is converted from m/s to ft/min for the calculation. The max(0.0, ...) ensures non-negative input to the power function. When fuels_wet > 0.5, BI is set to 0.0."
  },
  "equations": [
    {
      "rhs": {
        "args": [
          {
            "args": [
              0.5,
              "fuels_wet"
            ],
            "op": "<"
          },
          0,
          {
            "args": [
              3.01,
              {
                "args": [
                  {
                    "args": [
                      0,
                      {
                        "args": [
                          {
                            "args": [
                              "ms_to_fpm",
                              "ERC",
                              "SC"
                            ],
                            "op": "*"
                          },
                          "V_ref"
                        ],
                        "op": "/"
                      }
                    ],
                    "op": "max"
                  },
                  0.46
                ],
                "op": "^"
              }
            ],
            "op": "*"
          }
        ],
        "op": "ifelse"
      },
      "lhs": "BI"
    }
  ],
  "tolerance": {
    "rel": 1e-06
  },
  "analyses": [
    {
      "time_span": {
        "start": 0,
        "end": 1
      },
      "id": "default_burning_index",
      "parameters": {
        "fuels_wet": 0,
        "ERC": 20,
        "SC": 0.254
      },
      "description": "Default BurningIndex run with typical fire danger conditions"
    }
  ]
}