Estimating Biogenic VOC Estimating Biogenic VOC Emissions for the SCOS Domain Emissions for the SCOS Domain

Using the BEIGIS ModelUsing the BEIGIS Model

Michael T. BenjaminMichael T. BenjaminCalifornia Air Resources BoardCalifornia Air Resources Board

SCOS97-NARSTO Data Analysis ConferenceSCOS97-NARSTO Data Analysis ConferenceDiamond Bar, CaliforniaDiamond Bar, California

February 14, 2001February 14, 2001

Presentation OverviewPresentation Overview

• BackgroundBackground

• BEIGIS model inputsBEIGIS model inputs

• Validation of BEIGIS inputsValidation of BEIGIS inputs

• BEIGIS results for August 3-7, 1997 episodeBEIGIS results for August 3-7, 1997 episode

• Comparison with other inventoriesComparison with other inventories

• ConclusionsConclusions

BackgroundBackground

• BVOCs can be significant precursors to ozone and BVOCs can be significant precursors to ozone and PM2.5 formationPM2.5 formation

• Accurate BVOC inventories needed for control strategy Accurate BVOC inventories needed for control strategy developmentdevelopment

• Complicated in California due to climatic variability and Complicated in California due to climatic variability and heterogeneity of vegetationheterogeneity of vegetation

• BEIGIS is an ArcView GIS application developed by BEIGIS is an ArcView GIS application developed by ARB that uses high resolution California-specific inputsARB that uses high resolution California-specific inputs

BEIGIS Model InputsBEIGIS Model Inputs

• Landuse and Landcover databasesLanduse and Landcover databases

– GAP, county ag, SCAG, SANDAGGAP, county ag, SCAG, SANDAG

• Leafmass databasesLeafmass databases

– LAI, SLW, leafmass constantLAI, SLW, leafmass constant

• Plant species emission ratesPlant species emission rates

• Environmental parametersEnvironmental parameters

• Environmental correction algorithmsEnvironmental correction algorithms

Southern California Vegetation Classes

Source: GAP Database

August 1995 Leaf Area Index (LAI) Values

Source: Nikolov (1999) Grid cell size = 1 km

Validation of BEIGIS InputsValidation of BEIGIS Inputs

• ARB funding ground-based validation of satellite-ARB funding ground-based validation of satellite-derived GAP and LAI databasesderived GAP and LAI databases

• Approximately 15 validation sites statewideApproximately 15 validation sites statewide

• GAP database correctly predicts 65-75% of species GAP database correctly predicts 65-75% of species identified in ground surveysidentified in ground surveys

• Analysis of ground-based LAI data ongoing but Analysis of ground-based LAI data ongoing but preliminary results support use of Nikolov LAI preliminary results support use of Nikolov LAI databasedatabase

BEIGIS Model OutputBEIGIS Model Output

• Chemical species:Chemical species:

– Isoprene, monoterpenes, MBOIsoprene, monoterpenes, MBO

• Temporal resolution:Temporal resolution:

– Hourly, daily, episodicHourly, daily, episodic

• Spatial resolution:Spatial resolution:

– 1 km grid, 5 km grid, county, air basin1 km grid, 5 km grid, county, air basin

Isoprene Emissions1300 Hours, August 5, 1997

Monoterpene Emissions1300 Hours, August 5, 1997

Methylbutenol Emissions1300 Hours, August 5, 1997

0

10

20

30

40

50

0 12 0 12 0 12 0 12 0 12

BV

OC

(to

n/h

r)

Isoprene Monoterpenes Methylbutenol

BEIGIS Hourly EmissionsBEIGIS Hourly EmissionsSCOS Domain August 3-7, 1997SCOS Domain August 3-7, 1997

Aug 3Aug 3 Aug 4Aug 4 Aug 5Aug 5 Aug 6Aug 6 Aug 7Aug 7

0100200300

400500600700

8/3/97 8/4/97 8/5/97 8/6/97 8/7/97

Isoprene Monoterpenes Methylbutenol

BEIGIS Daily EmissionsBEIGIS Daily EmissionsSCOS Domain August 3-7, 1997SCOS Domain August 3-7, 1997

Study Iso Mono Iso + Mono

SCAQMP (1991) - - 150-250

SCAQMP (1994) - - 111-275

Benjamin et al. (1997) 94-107 86-92 180-200

BEIGIS (2000) 188 94 282

Comparison of BVOC Comparison of BVOC Inventories for the SCAQMD Inventories for the SCAQMD

Comparison of BVOC Comparison of BVOC Inventories for SCOS DomainInventories for SCOS Domain

0

500

1000

1500

2000

2500

BV

OC

(T

PD

)

BEIS1 BEIS2 BEIGIS

Contribution of Biogenics to Contribution of Biogenics to Overall ROG InventoryOverall ROG InventoryAugust 5, 1997August 5, 1997

76%

24%

Biogenic Anthropogenic

45%

42%

13%

Biogenic Anthropogenic Wildfires

Including WildfiresIncluding Wildfires Excluding WildfiresExcluding Wildfires

ConclusionsConclusions

• High resolution California-specific inputs used High resolution California-specific inputs used with BEIGIS model to estimate BVOC emissions with BEIGIS model to estimate BVOC emissions for the SCOS domainfor the SCOS domain

• 450 - 700 TPD BVOC emitted in SCOS domain 450 - 700 TPD BVOC emitted in SCOS domain during August 3-7, 1997 ozone episodeduring August 3-7, 1997 ozone episode

• BVOC inventory ~ 25% SCOS ROG inventory, BVOC inventory ~ 25% SCOS ROG inventory, assuming anthropogenic inventory of 2100 TPD assuming anthropogenic inventory of 2100 TPD (excluding wildfire emissions)(excluding wildfire emissions)