Gridded biome bgc simulation with explicit fire disturbance
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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

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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.

Illustrate Biome-BGC modification for explicit fire-disturbance simulation


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

Raw Data

Size and location

Before 1959: constant fire mortality

After 1959: external fire mortality from the raw data


Considering Explicit Fire-Disturbance

Generate fire grid

Year

cell[i,j] annual fire file

83

84

85

86

87


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

  • 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

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

300km

660km


Topography

N

N


Climate (3-yr mean)

Tmax

Tmin

Precipitation

Radiation


Sample Result 1 – Land cover

DBF

(412, 87.5 g/m2)

Grass

(347, 48.6 g/m2)

DC

(279, 26.2 g/m2)

WC

(140, 8.7 g/m2)


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

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

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

00

+10 -10

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

DBF, Const. CO2


Climate Scenario

1.2P

0.8P

1.2P(+2T)

1.2P(-2T)

0.8P(+2T)

0.8P(-2T)


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)


Grass

PSN (gC m-2 d-1)

yearday

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


COOP. Weather Station, Alabama


Warm (13.3 oC)

Cool

(6.2 oC)


Model Overview

Soil temperature model

Spatially-explicit estimations

Field sampling & measurement

RS

DEM

Meteorological Data

Soil Data

1.Respiration

2.Temperature

3.Water content

4.SOM

Field LAI

NDVI

Meteorological Models

1.Air temperature

2.Precipitation

3.Solar radiation

4.Vapor pressure deficit

LAI-NDVI model

Soil moisture model

Soil respiration 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

Landsat TM image in Aug. 1991

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


LAI-NDVI Model : Leaf Emergence and Expand

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

135 140 145


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