Biogenic Emissions Biogenic Emissions Modeling: MEGAN Modeling: MEGAN Christine Wiedinmyer, Tiffany Duhl, Ulzi Vanchindorj, Alex Guenther National Center for Atmospheric Research Tanarit Sakulyanontvittya, Jana Milford University of Colorado / Environ Serena Chung, Jack Chen Washington State University July 29, 2008 WRAP Workshop
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Biogenic Emissions Modeling: MEGAN Christine Wiedinmyer, Tiffany Duhl, Ulzi Vanchindorj, Alex Guenther National Center for Atmospheric Research Tanarit.
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Christine Wiedinmyer, Tiffany Duhl, Ulzi Vanchindorj, Alex Guenther
National Center for Atmospheric Research
Tanarit Sakulyanontvittya, Jana MilfordUniversity of Colorado / Environ
Serena Chung, Jack ChenWashington State University
July 29, 2008 WRAP Workshop
Emissions for Chemical Transport Models
• Point
• Area
• Mobile– On-road– Off-road
• Fire
• Biogenic
Emissions of trace gases from vegetation: Biogenic Emissions
Controlling variables:
- vegetation
* species
* vegetation density
* leaf area index
- meteorology
* temperature
* light
- climate
* season
* water availability
….
Biogenic Emissions Modeling: MEGAN
• MEGAN: Model of Emissions of Gases and Aerosols from Nature– Based on Guenther et. al., Atmospheric Chemistry and Physics,
2006• Other papers forthcoming
– 134 emitted chemical species• Isoprene• Monoterpenes• Oxygenated compounds• Sesquiterpenes• Nitrogen oxide• Lumped to 20+ categories
– 1 km2 resolution
– Input files available at: http://cdp.ucar.edu
Biogenic Emissions Modeling: MEGAN
• MEGAN Versions– MEGAN v0.0, v0.1, v0.2, v0.3
• Developed by Jack Chen (WSU) for EPA STAR Grant• Emission factor maps of isoprene, monoterpenes, and other volatile organic
compounds (OVOCs) developed• Monthly emission activity maps applied (light, temperature and LAI – dependent).• V0.3 used with global model (MOZART)
– MEGAN v1.0 • Isoprene only• Published by Guenther et al., Atmos. Chem. & Phys., 2006• Included within Global Community Land Model (Heald et al., 2008)
– MEGANv2• Includes emissions of other compounds• Version 2.04 described by Sakyluononvittaya et al., ES&T, 2008
– Online within WRF-chem– Offline version runs like SMOKE processor
• Version 2.14 (?) Canopy model
SMageCEEM
TPLAICE
EM: Emission (g m-2 hr-1): Emission Factor (g m-2 hr-1)CE: Canopy Factorage: Leaf Age FactorSM : Soil Moisture Factor: Loss and Production within plant canopyLAI : Leaf Area Index FactorP : PPFD Emission Activity Factor (light-dependence)T: Temperature Response Factor
Tdaily = daily average air temperature (K) representative of
model simulation periodCT1 = 80
CT2 = 200
For Monoterpenes:From Guenther et al., 1995
MEGAN v2.04
• The algorithm and data for SM and are not yet ready. They are assigned to 1.0
• The light dependent factor is only applied to fractions of emission factors based on biological function of plants.
• No explicit canopy model– Xuemei Wang has implemented canopy model in one version
SMageCEEM
TPLAICE
1 1
MEGAN 2.04
• Designed to work within the SMOKE framework – Specifically for regional air quality model input processing
• Three Modules– MG2IOAPI
• This module will convert text format to IOAPI-netCDF format.
– MEGAN• This is the primary MEGAN module. The gamma values are calculated within
this module.
– MG2MECH• This model calculates the final emission rates and speciates and/or converts
MEGAN emission output to chemical mechanism species. The current available mechanisms include CBMZ, SAPRC99, RADM2, and RACM.
– Developed by Tanarit Sakulyanontvittaya (University of Colorado) with assistance from Jana Milford (U. Colorado), Christine Wiedinmyer and John Orlando ( National Center for Atmospheric Research), William Stockwell (Howard University), Greg Yarwood (ENVIRON), and Rahul Zaveri (Pacific Northwest National Laboratory).
Output is I/O API file ready for input to SMKMRG
MEGAN INPUT FILE
• MEGAN input file needs to be preprocessed before model simulation– Documentation being developed
– Currently requires geographic processing software
• File must include:– Model Grid information
– Normalized Emission factors• From NCAR Community Data Portal• Values from downloaded grid converted from g/km2/hr to mole/km2/hr
– Monthly Leaf Area Index (LAI)• From NCAR Community Data Portal
– Plant Functional Type (PFT)• From NCAR Community Data Portal
MEGAN Emission Estimates: Isoprene
Max = 4358 g/km2-hrTotal average emission = 7417 tons/hr
Max = 10542 g/km2-hrTotal average emission = 12145 tons/hr
Isoprene Emissions Isoprene Emissions
MEGAN vs. BEIS3.11
Average Isoprene Emission EstimatesJuly 2004
Serena Chung, WSU
Max = 77 g/km2-hrTotal average emission = 215 tons/hr
Max = 56 g/km2-hrTotal average emission = 163 tons/hr
NO Emissions
MEGAN Emission Estimates: Nitrogen Oxide
NO Emissions
Max = 852 g/km2-hrTotal average Emission = 2205 tons/hr
Max = 591 g/km2-hrTotal average Emission = 1852 tons/hr
Monoterpene Emissions
MEGAN Emission Estimates: Monoterpenes
Monoterpene Emissions
Max = 342 g/km2-hrTotal average Emission = 786 tons/hr
Max = 135 g/km2-hrTotal average Emission = 298 tons/hr
Max = 398 g/km2-hrTotal average Emission = 786 tons/hr
SQT Emissions SQT Emissions SQT Emissions
MEGAN Emission Estimates: Sesquiterpenes
Summary
• MEGAN is a new biogenic emissions model
• MEGAN v2.04 is ready to be used to create model-ready biogenic emissions – Download at http://cdp.ucar.edu
– Input file for MEGAN needs to be preprocessed by users
• Emission estimates from MEGAN have significant differences from BEIS estimates– Evaluation and validation is needed.
Table 1: Input parameters for MEGANv2.0, including class of compound (1-20), base emission factors (g m-2 hr-1) for broadleaf trees (EFBT), Needleaf Trees (EFNT), Shrubs (EFSHR), and Crops/Grasses (EFCG). is the dimensionless parameter
used to calculate T for compounds other than isoprene. The light dependent fraction (LDF) is the fraction of the total
emissions that should have a light dependency assigned.