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A Tale of Two Models: A Comparison of the Biogenic Emission Inventory System BEIS3'14 and Model of E

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Title: A Tale of Two Models: A Comparison of the Biogenic Emission Inventory System BEIS3'14 and Model of E


1
A Tale of Two Models A Comparison of the
Biogenic Emission Inventory System (BEIS3.14) and
Model of Emissions of Gases and Aerosols from
Nature (MEGAN 2.04)
What are the major differences in these two
models that estimate emissions from biogenic
sources?
It was the best of times, it was the worst of
times, it was the age of wisdom, …
George Pouliot 7th Annual CMAS Conference 7
October 2008
2
Topics to be Discussed
  • Brief introduction to MEGAN and BEIS
  • Biogenic Emissions Inventory System (BEIS v3.14)
  • Model of Emissions of Gases and Aerosols from
    Nature (MEGAN v2.04)
  • Spatial differences between two models for an
    annual simulation
  • Temporal differences between the two models
  • Future Work

3
Details about BEIS3.14
  • Based on BELD3 vegetation database (limited to
    North America)
  • Emission factors derived for USGS land use types,
    crops, and specific tree types
  • Soil NO algorithm is a function of temperature,
    rainfall, and growing season (Yienger and Levy,
    1995)
  • Simple canopy model for Light adjustment
  • Summer/Winter factors based on freeze dates

4
Details about MEGANv2.04
  • Gridded emission factors based on global datasets
    for 11 species
  • Emission factors for all other species based on 4
    functional plant types (broadleaf, needles,
    shrubs, etc)
  • NO emission estimates are a function of
    temperature only
  • Simple parameterization of canopy light
    attenuation in Version 2.04 Version 2.10
    will have an explicit canopy model
  • Monthly gridded leaf area indices (LAIs) used for
    seasonal variation

Guenther, A., T. Karl, et al. (2006). "Estimates
of global terrestrial isoprene emissions using
MEGAN (Model of Emissions of Gases and Aerosols
from Nature)." Atmos. Chem. Phys. 6(11)
3181-3210.
3
5
Isoprene Emissions(MG/yr)
BEIS
MEGAN
6
Monoterpenes Emissions (Mg/yr)
BEIS
MEGAN
Hot spot
decrease
7
Sesquiterpenes Emissions (Mg/yr)
BEIS
MEGAN
8
Methanol Emissions (Mg/yr)
BEIS
MEGAN
9
Formaldehyde Emissions (Mg/yr)
BEIS
MEGAN
10
Soil Nitric Oxide
BEIS
MEGAN
11
Summary of Spatial Differences
  • Isoprene Relative to BEIS, MEGAN generates
    higher isoprene in all areas, especially the
    southern U.S.
  • Monoterpenes MEGAN is lower in Canada,
    southwestern U.S., and northwestern U.S.
  • Sesquiterpenes MEGAN is lower in midwestern U.S.
  • Methanol MEGAN is higher in all areas
  • Formaldehyde MEGAN is lower in all areas,
    especially the southwestern U.S.

10
12
Percent Difference BEIS and MEGAN (based on 2003
annual emissions saprc99)
MEGAN is higher - BEIS is higher
11
13
Isoprene 36km daily domain totals 2003
14
Monoterpenes 36km daily domain totals 2003
15
Sesquiterpenes 36km daily domain totals 2003
16
Methanol 36km daily domain totals 2003
17
Formaldehyde 36km daily domain totals 2003
18
Soil Nitric Oxide 36km daily domain totals 2003
19
Summary
  • Comparison of BEIS3.14 and MEGAN2.04 made for
    2003 for SAPRC99 mechanism species
  • MEGAN is higher for Isoprene, methanol, acetone,
    ethene
  • BEIS is higher forMonoterpenes, sesquiterpenes,
    formaldehyde, other VOCs, soil NO
  • BEIS has a more detailed soil NO algorithm
  • MEGAN and BEIS have different spatial patterns
    (different normalized emission inputs)

18
20
Future Work
  • Compare CMAQ results for BEIS3.14 and MEGAN2.04
    for 3 week period in 2003
  • Incorporate MEGAN into CMAQ as an option compared
    to BEIS
  • MEGANv2.10 is expected by the end of the year
    (will include updated canopy model)
  • Eventually may replace BEIS with MEGAN
  • Disclaimer Although this work was reviewed by
    EPA and approved for publication, it may not
    necessarily reflect official Agency policy

19
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