Wildfire Emissions Updated Methodology

Wildfire EmissionsUpdated Methodology

Neva Sotolongo

Emission Inventory Branch

Overview

• Emission Estimation System (EES)– Source data - FRAP – Emission calculation methodology - FOFEM– Fuel moisture inputs

• Changes and assumptions in methodology

• Results

Wildfire DefinitionA natural event that burns a variety of vegetation types ranging in age, size and density; caused by natural and human activity such as lightning or arson, and suppressed by fire fighters. This category does not include prescribed burns or wildland fire use (WFU) fires.

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Source Data

• FRAP dataset – 15,000 fires that date back to late 1800’s– updated annually– most comprehensive dataset available– duplicate fire resolution

• 2002 dataset– 225 fires– 486,000 acres– intersected with Air Basin, District & County– clipped fires that cross state boundary

• Limitations

Emission Estimation

• CAMFER EES - GIS based emission estimation model designed for California

– FOFEM - smoke emission estimation methodology

– GAP Layer - vegetation landcover of CA

– Thousand-Hour Fuel Moisture Grid - moisture input

Wildfire footprint is overlaid onGAP vegetation layer, calculatingthe amount of each fuel consumed in the fire. Fuel loading is assigned for each fuel component that make up the vegetation type.

Fuel Components

Fuel ComponentConsumption Assumption

Fuel Loading

Total Consumed

Litter 100% 1.8 1.8Wood 0-1 inch 90% 1.3 1.2Wood 1-3 inch 65% 1.9 1.2Wood 3+ inch NFDR-TH 32.0 NFDR-THDuff NFDR-TH 56.0 NFDR-THHerbaceous 100% 0.2 0.2Shrub 60% 0.3 0.2Tree regeneration 60% 0.1 0.1Canopy branchwood 50% 3.0 1.5Canopy foliage 100% 6 6.0

Sierra Nevada M ixed Conifer

Thousand-Hour Fuel Moisture

TH-HR Fuel Moisture

Fuel ComponentFuel

LoadingMoisture Content Flaming Smoldering

Total Consumed

Litter 1.8 -- -- -- 1.8Wood 0-1 inch 1.3 -- -- -- 1.2Wood 1-3 inch 1.9 -- -- -- 1.2Wood 3+ inch 32.0 10.0 21.5 5.4 26.9Duff 56.0 40.0 15.5 23.2 38.7Herbaceous 0.2 -- -- -- 0.2Shrub 0.3 -- -- -- 0.2Tree regeneration 0.1 -- -- -- 0.1Canopy branchwood 3.0 -- -- -- 1.5Canopy foliage 6 -- -- -- 6.0

Sierra Nevada Mixed Conifer

Emission Factors (lbs/ton)

Fuel component Wet Mod Dry Wet Mod Dry Wet Mod Dry Wet Mod DryLitter, wood 0-1 in 9.3 9.3 9.3 7.9 7.9 7.9 52.4 52.4 52.4 2.1 2.1 2.1Wood 1-3 in 14.0 14.0 14.0 11.9 11.9 11.9 111.4 111.4 111.4 4.5 4.5 4.5Wood 3+ in 26.6 21.6 19.1 22.5 18.3 16.2 268.9 205.8 174.4 10.8 8.2 7.0Herb, shrub, regen 25.1 25.1 25.1 21.3 21.3 21.3 249.2 249.2 249.2 10.0 10.0 10.0Duff 28.2 30.4 30.4 23.9 25.8 25.8 288.6 316.1 316.1 11.5 12.6 12.6Canopy fuels 25.1 25.1 25.1 21.3 21.3 21.3 249.2 249.2 249.2 10.0 10.0 10.0

Fuel component Wet Mod Dry Wet Mod Dry Wet Mod Dry Wet Mod DryLitter, wood 0-1 in 3.7 3.7 3.7 0.5 0.5 0.5 8.2 8.2 8.2 2.5 2.5 2.5Wood 1-3 in 7.8 7.8 7.8 1.1 1.1 1.1 8.0 8.0 8.0 2.5 2.5 2.5Wood 3+ in 18.8 14.4 12.2 2.7 2.1 1.7 7.3 7.6 7.7 2.2 2.3 2.4Herb, shrub, regen 17.4 17.4 17.4 2.5 2.5 2.5 7.4 7.4 7.4 2.3 2.3 2.3Duff 20.2 22.1 22.1 2.9 3.2 3.2 7.2 7.1 7.1 2.2 2.2 2.2Canopy fuels 17.4 17.4 17.4 2.5 2.5 2.5 7.4 7.4 7.4 2.3 2.3 2.3

CH4PM10 PM2.5 CO

SO2TNMHC NH3 NOx

Seasonal Variation 2002

0

50,000

100,000

150,000

200,000

250,000

300,000

Acr

es B

urn

ed

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Ignition Date

Acres Burned

PM10 Emissions

Assumptions

• Gridded NFDR-TH moisture - 2002

• FRAP dataset limitations

• FOFEM assumes 100% of burn area experiences fire

Changes

• Combined EIC (CES) codes - “All Vegetation”– “Grass and Woodlands” and “Timber and Brush”

• Actual fire perimeters and location

• Vegetation specific emission estimates

What’s Next

• Forecasting future wildfire emissions

• Prescribed burn methodology update and projections

• WFU emissions

Forecasting Wildfire Emissions - Baseline

• Ten-year average - 1994 through 2003 wildfires– normalize erratic annual spatial wildfire distribution– ample yet manageable sample set – adjusts for reporting inconsistencies– consistency and quality data available– reflects climate trends

Ten-Year Average

• 1994 to 2003 sample set– 2,314 fires

– intersected with Air Basin, District & Co

– clipped fires that cross state boundary

– ~10% fires had no month data

• Adjustment for extreme wildfires – San Diego

– San Bernardino portion of the SCAB

Seasonal Variation

0

100,000

200,000

300,000

400,000

500,000

600,000

Tot

al E

mis

sion

s (t

ons)

Jan

Feb

Mar

Apr

May

June

July

Aug

Sep

t

Oct

Nov

Dec

Neva Sotolongo

Air Resources Board

(916) 323-4887

nsotolon@arb.ca.gov

Contact Information