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Gridded Biome-BGC Simulation with Explicit Fire-disturbance. Sinkyu Kang, John Kimball, Steve W. Running Numerical Terradynamic Simulation Group, School of Forestry, Univeristy of Montan. Purpose. Demonstrate Gridded Biome-BGC run in BOREAS.

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Gridded biome bgc simulation with explicit fire disturbance

Gridded Biome-BGC Simulation with Explicit Fire-disturbance

Sinkyu Kang, John Kimball, Steve W. Running

Numerical Terradynamic Simulation Group, School of Forestry, Univeristy of Montan



Demonstrate Gridded Biome-BGC run in BOREAS.

Illustrate Biome-BGC modification for explicit fire-disturbance simulation

Process of gridded bgc
Process of Gridded BGC

  • Batch run of Biome-BGC combined with input and output modules

  • Using IDL platform

Spatial & temporal data

INI, EPC, MET file for point Biome BGC run

Batch run of point Biome BGC

Generate gridded outputs

Considering explicit fire disturbance
Considering Explicit Fire-Disturbance

Raw Data

Size and location

Before 1959: constant fire mortality

After 1959: external fire mortality from the raw data

Considering explicit fire disturbance1
Considering Explicit Fire-Disturbance

Generate fire grid


cell[i,j] annual fire file






Considering explicit fire disturbance2
Considering Explicit Fire-Disturbance

Modifed INI & EPC files

1.0 (DIM) multiplier for shortwave radiation

CO2_CONTROL (keyword - do not remove)

1 (flag) 0=constant 1=vary with file 2=constant, file for Ndep

286.923 (ppm) constant atmospheric CO2 concentration

kco21862.txt (file) annual variable CO2 filename

FIRE_CONTROL (keyword - do not remove)

1 (flag) 0=constant fire mortality 1=vary with file

fire-5-14.txt (file) annual variable fire mortality (year fire_mortality)

SITE (keyword) start of site physical constants block

Run Modified Biome-BGC

ECOPHYS ENF-cool (wet conifer)

1 (flag) 1 = WOODY 0 = NON-WOODY


0.005 (1/yr) annual whole-plant mortality fraction

0.005 (1/yr) mean annual fire mortality fraction

0.26 (1/yr) annual carbon fraction consumed by fire

1.5 (ratio) (ALLOCATION) new fine root C : new leaf C

1.1 (ratio) (ALLOCATION) new stem C : new leaf C

ET (mm/y) & NPP (gC/m2/y)

LAI (m2/m2)

Daily fire mortality

Constant fire mortality > 1959 < Explicit fire occurrence

Internal fire-disturbance

External fire-disturbance

Modification of biome bgc
Modification of Biome-BGC

  • Biome-BGC v.411

    • 47 source files

    • 8 header files

    • 2 library files

  • In this study, even this small change demanded

    • modification of 7 source files

    • modification of 4 header files

    • addition of a new subroutine source file

Application to the boreal forest biome
Application to the Boreal Forest Biome

Experimental Design

Grid size (simulation unit): 66 columns and 60 rows (ca. 660300km2)

Each simulation uses

  • identical land cover and soil property over the entire grid

  • identical spatial meteorological variable (1994~1996)

    Every simulation differs in

  • land cover types (DBF, Grass, DC, WC)

  • constant or varying ambient CO2 and internal or external fire-disturbance

  • Nine climate change scenario (control, 2oC, 20% precipitation)

    Total 108 cases of gridded Biome-BGC runs

Land cover
Land Cover



Climate 3 yr mean
Climate (3-yr mean)





Sample result 1 land cover
Sample Result 1 – Land cover


(412, 87.5 g/m2)


(347, 48.6 g/m2)


(279, 26.2 g/m2)


(140, 8.7 g/m2)

Sample result 2 co2
Sample Result 2 – CO2

WC, Const. CO2

(140, 8.7 g/m2)

Difference (23, 2.8 g/m2)

Const. CO2 – Increasing CO2

WC, Increasing CO2

(163, 11.1 g/m2)

Sample result 3 fire
Sample Result 3 - Fire

Difference (-1.4, 3.7 g/m2)

External fire – Increasing CO2

WC, Increasing CO2

(163, 11.1 g/m2)

WC, External fire

(161, 11.8 g/m2)

Sample result 4 climate change
Sample Result 4 – Climate Change

PRCP*TEMP: PRCP(-1,0,+1), TEMP(-1,0,+1), EX: +1-1 (1.2*prcp & -2 of Temp.)


+10 -10

+1+1 +1-1 -1+1 -1-1

DBF, Const. CO2

Climate scenario
Climate Scenario







Future consideration
Future consideration

  • Model Initialization

    Spin-up run:

    • initialize soil and vegetation variable at balanced equilibrium condition

    • time consuming process as number of gridcells increase

      Extrapolation from satellite measurement:

    • satellite-driven LAI  initialize vegetation carbon variables using allometry rules (Landsat & MODIS in watershed and regional scale)

  • Replace model phenology with RS phenology (ex. MODIS)


PSN (gC m-2 d-1)


Reinitialize using

satellite-driven LAI + allometry from spin-up simulation

MOD17: daily PSN (MOD17A2)

BGC: daily PSN with spin-up simulation

MOD15-BGC: daily PSN using input LAI from MOD15

Warm (13.3 oC)


(6.2 oC)

Model overview
Model Overview

Soil temperature model

Spatially-explicit estimations

Field sampling & measurement



Meteorological Data

Soil Data



3.Water content


Field LAI


Meteorological Models

1.Air temperature


3.Solar radiation

4.Vapor pressure deficit

LAI-NDVI model

Soil moisture model

Soil respiration model

Lai model
LAI model

LAI model

LAI-NDVI model

Leaf emergency (Je)

 (Ta-5oC) > 88oC

Maximum LAI (Jm)

(Aug. 15 in this study)

End of litterfall (Jb)

 (Ta-10oC) < -150oC

NDVI (Landsat TM,

August, 1991)

Mean 0.55

STDEV 0.13

(solid dots are locations where LAI was measured.)

Lai ndvi model
LAI-NDVI model

Landsat TM image in Aug. 1991

LAI measured in Aug. 1998 and 1999 using LI-COR 2000

Lai ndvi model leaf emergence and expand
LAI-NDVI Model : Leaf Emergence and Expand

120 (0~3.8 m2 m-2) 125 130

135 140 145