29 Model of Emissions of Gases and Aerosol from Nature Version …
191
29.6 Recommendations for Future Work
Forests are an important source of monoterpene emissions, but the rates remain highly
uncertain. High quality measurements of monoterpene emission factors should be
conducted to characterize the dominant vegetation. Emission factors for isoprene,
including low or zero emissions, and other compounds, including sesquiterpenes and
stress compounds, could be estimated by the same study.
The oaks are a diverse genus and include some European species that do not emit
isoprene. The isoprene EF of more of the dominant oaks, including the savannah and
shrub oaks that are relatively understudied, should be investigated with high quality
measurements to quantify any within-genera variation.
Soil NO emissions are important in agricultural areas. Improved crop landcover
and nitrogen fertilizer rate distributions should be incorporated into MEGAN along
with advances in representation of other processes controlling soil NO emissions [2].
Further development and testing of MEGAN3 is recommended, including integration of additional MEGAN-EFP landcover and emissions data especially non-tree
landcover, compounds other than isoprene and monoterpenes, and regions outside
of southeastern and southcentral US.
Questions and Answers
Questioner: Clemens Mensink, Flemish Institute for Technological Research
(VITO)
Question: How do you assign emission factor quality (J rating) – what are the criteria?
Answer: This is an important question that points directly to the need for community
engagement in developing the MEGAN3 emission factor database. At this stage, only
emission factors that were developed according to the Niinemets protocols [4) are
assigned the highest quality rating (J = 4) with the majority of data assigned one of
two low quality ratings: J = 0 for semi-quantitative screening studies conducted primarily in the 1960s–1980s using static branch enclosures to characterize understory
and/or cut branches and J = 1 for more recent measurements that do not meet the
Niinemets protocols. Having a quality rating provides motivation and opportunity
for wider community engagement in assigning quality ratings as well as expanding
the emission factor database. A primary motivation for developing the MEGAN3
emission factor preprocessor (EFP) is to encourage community-wide contributions
that improve MEGAN3 for everyone.
Questioner: Paul Makar, Environment and Climate Change Canada
Question: Can the MEGAN canopy model provide information on light intensity at
different heights within the forest canopy that could be used to drive air chemistry
models?
Answer: The off-line version of MEGAN has a canopy environment model that
explicitly simulates leaf-level light intensity and temperature on both sun and shade
leaves at five canopy levels and could be adapted to drive photolysis rates for air
quality models. [3] have demonstrated the importance of including in-canopy photolysis, chemistry, and turbulence in air quality model simulations and an effort to
191
29.6 Recommendations for Future Work
Forests are an important source of monoterpene emissions, but the rates remain highly
uncertain. High quality measurements of monoterpene emission factors should be
conducted to characterize the dominant vegetation. Emission factors for isoprene,
including low or zero emissions, and other compounds, including sesquiterpenes and
stress compounds, could be estimated by the same study.
The oaks are a diverse genus and include some European species that do not emit
isoprene. The isoprene EF of more of the dominant oaks, including the savannah and
shrub oaks that are relatively understudied, should be investigated with high quality
measurements to quantify any within-genera variation.
Soil NO emissions are important in agricultural areas. Improved crop landcover
and nitrogen fertilizer rate distributions should be incorporated into MEGAN along
with advances in representation of other processes controlling soil NO emissions [2].
Further development and testing of MEGAN3 is recommended, including integration of additional MEGAN-EFP landcover and emissions data especially non-tree
landcover, compounds other than isoprene and monoterpenes, and regions outside
of southeastern and southcentral US.
Questions and Answers
Questioner: Clemens Mensink, Flemish Institute for Technological Research
(VITO)
Question: How do you assign emission factor quality (J rating) – what are the criteria?
Answer: This is an important question that points directly to the need for community
engagement in developing the MEGAN3 emission factor database. At this stage, only
emission factors that were developed according to the Niinemets protocols [4) are
assigned the highest quality rating (J = 4) with the majority of data assigned one of
two low quality ratings: J = 0 for semi-quantitative screening studies conducted primarily in the 1960s–1980s using static branch enclosures to characterize understory
and/or cut branches and J = 1 for more recent measurements that do not meet the
Niinemets protocols. Having a quality rating provides motivation and opportunity
for wider community engagement in assigning quality ratings as well as expanding
the emission factor database. A primary motivation for developing the MEGAN3
emission factor preprocessor (EFP) is to encourage community-wide contributions
that improve MEGAN3 for everyone.
Questioner: Paul Makar, Environment and Climate Change Canada
Question: Can the MEGAN canopy model provide information on light intensity at
different heights within the forest canopy that could be used to drive air chemistry
models?
Answer: The off-line version of MEGAN has a canopy environment model that
explicitly simulates leaf-level light intensity and temperature on both sun and shade
leaves at five canopy levels and could be adapted to drive photolysis rates for air
quality models. [3] have demonstrated the importance of including in-canopy photolysis, chemistry, and turbulence in air quality model simulations and an effort to