biogenic emissions modeling: megan christine wiedinmyer, tiffany duhl, ulzi vanchindorj, alex...

Biogenic Emissions Biogenic Emissions Modeling: MEGAN Modeling: MEGAN

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

MEGAN Framework: Calculation of emissions

(Guenther et al., 2006)

Emission Factor Maps: Isoprene

Guenther et al., AC&P, 2006

Emission Factor Maps: a-Pinene

Emission Factor Maps: Methanol

MEGAN Framework: simple Canopy Environment calculations

sT TT exp

)exp(1(*(

)exp(

212

12

xCCC

xCCE

TTT

TTOPTT

00831.0

)/1()/1[( hropt TTx

)297(*08.0(exp(*75.1 dailyOPT TE

))297(*6.0(313 dailyopt TT

For isoprene:

Follow equation 14 of Guenther et al. (2006):

Where

Thr = hourly air temperature (K)

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


Isoprene Emissions Isoprene Emissions

MEGAN vs. BEIS3.11

Average Isoprene Emission EstimatesJuly 2004

Serena Chung, WSU



NO Emissions

MEGAN Emission Estimates: Nitrogen Oxide

NO Emissions

Max = 852 g/km2-hrTotal average Emission = 2205 tons/hr


Monoterpene Emissions

MEGAN Emission Estimates: Monoterpenes

Monoterpene Emissions




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.

Christine [email protected]*Limited support available

180,0 aa

1800

)400(*0005.01**9.0*46.2*)sin( 3

a

when

Pa dailyP

toa

ac

Pa

P

*)sin(

5.0*)66.4(*2sm

molDSWPac

]365/)10(14.3*2cos[*993000 DOYPtoa

P = the dependence of emissions on lightThis is based on equations 11-13 of Guenther et al. (2006).

Where: P = 0 when

and

Where = above canopy PPFD transmission (non-dimensional)Pdaily = daily average above canopy PPFD (mol m-2 s-1)

a = solar angle (degree)where Pac = above canopy PPFD (mol m-2 s-1)

Ptoa = PPFD at the top of atmosphere (mol

m-2 s-1)

where DOY = day of year


LAI = the dependence of the emissions on Leaf Area Index.

LAI = 0.49 * LAIc /[(1+0.2* LAIc2)0.5]`

Where: LAIc = leaf area index of the current month

(or the month that is being simulated)


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.

ClassNameClass

ID EFBT EFNT EFSHR EFGC Leaf Age

Case LDF

MBO 2 5 100 8 0.1 0.09 5 1

Myrcene 3 20 75 22 0.3 0.09 2 0.05

Sabinene 4 45 70 50 0.7 0.09 2 0.1

limonene 5 45 100 52 0.7 0.09 2 0.05

carene <3-> 6 18 160 25 0.3 0.09 2 0.05

ocimene <trans beta> 7 90 60 85 1 0.09 2 0.8

pinene <beta-> 8 90 300 100 1.5 0.09 2 0.1

pinene <alpha-> 9 180 450 200 2 0.09 2 0.1

farnescene <alpha-> 10 60 30 50 0.9 0.15 3 0.8

caryophyllene <beta-> 11 60 75 65 1.2 0.15 3 0.8

Methanol 12 400 400 400 400 0.09 4 0

Acetone 13 100 100 100 100 0.11 1 0

Acetaldehyde and ethanol 14 120 120 120 120 0.13 1 0

formic acid, formaldehyde, acetic acid 15 70 70 70 70 0.09 1 0

methane 16 300 300 300 300 0.05 1 0.75

nitrogen gases: NO, NH3, N2O 17 5 5 41 200 0.07 1 0

other monoterpenes 18 87.2 180.4 108.2 4.81 0.09 2 0.1

other sesquiterpenes 19 107.7 125.4 104.4 1.83 0.15 3 0.8

other VC 20 969.2 969.2 969.2 969.2 0.09 1 0.75




SQT Emissions SQT Emissions SQT Emissions

MEGAN Emission Estimates: Isoprene

biogenic emissions modeling: megan christine wiedinmyer, tiffany duhl, ulzi vanchindorj, alex...

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