Isoprene and monoterpene emissions in south-east Australia: comparison of a multi-layer canopy model with MEGAN and with atmospheric observations
One of the key challenges in atmospheric chemistry is to reduce the uncertainty of biogenic volatile organic compound (BVOC) emission estimates from vegetation to the atmosphere. In Australia, eucalypt trees are a primary source of biogenic emissions, but their contribution to Australian air shed...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2018-05-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/18/7539/2018/acp-18-7539-2018.pdf |
| _version_ | 1819174628702027776 |
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| author | K. M. Emmerson M. E. Cope I. E. Galbally S. Lee S. Lee P. F. Nelson |
| author_facet | K. M. Emmerson M. E. Cope I. E. Galbally S. Lee S. Lee P. F. Nelson |
| author_sort | K. M. Emmerson |
| collection | DOAJ |
| description | One of the key challenges in atmospheric chemistry is to reduce the uncertainty of biogenic
volatile organic compound (BVOC) emission estimates from vegetation to the
atmosphere. In Australia, eucalypt trees are a primary source of biogenic
emissions, but their contribution to Australian air sheds is poorly
quantified. The Model of Emissions of Gases and Aerosols from Nature (MEGAN)
has performed poorly against Australian isoprene and monoterpene
observations. Finding reasons for the MEGAN discrepancies and strengthening
our understanding of biogenic emissions in this region is our focus. We
compare MEGAN to the locally produced Australian Biogenic Canopy and Grass
Emissions Model (ABCGEM), to identify the uncertainties associated with the
emission estimates and the data requirements necessary to improve isoprene
and monoterpene emissions estimates for the application of MEGAN in
Australia. Previously unpublished, ABCGEM is applied as an online biogenic
emissions inventory to model BVOCs in the air shed overlaying Sydney,
Australia. The two models use the same meteorological inputs and chemical
mechanism, but independent inputs of leaf area index (LAI), plant functional
type (PFT) and emission factors. We find that LAI, a proxy for leaf biomass,
has a small role in spatial, temporal and inter-model biogenic emission
variability, particularly in urban areas for ABCGEM. After removing LAI as
the source of the differences, we found large differences in the emission
activity function for monoterpenes. In MEGAN monoterpenes are partially light
dependent, reducing their dependence on temperature. In ABCGEM monoterpenes
are not light dependent, meaning they continue to be emitted at high rates
during hot summer days, and at night. When the light dependence of
monoterpenes is switched off in MEGAN, night-time emissions increase by
90–100 % improving the comparison with observations, suggesting the
possibility that monoterpenes emitted from Australian vegetation may not be
as light dependent as vegetation globally. Targeted measurements of emissions
from in situ Australian vegetation, particularly of the light dependence
issue are critical to improving MEGAN for one of the world's major biogenic
emitting regions. |
| first_indexed | 2024-12-22T20:42:00Z |
| format | Article |
| id | doaj.art-83b3221a26114c0da61f6d836b2b3ba4 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-22T20:42:00Z |
| publishDate | 2018-05-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-83b3221a26114c0da61f6d836b2b3ba42022-12-21T18:13:18ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242018-05-01187539755610.5194/acp-18-7539-2018Isoprene and monoterpene emissions in south-east Australia: comparison of a multi-layer canopy model with MEGAN and with atmospheric observationsK. M. Emmerson0M. E. Cope1I. E. Galbally2S. Lee3S. Lee4P. F. Nelson5Climate Research Centre, CSIRO, PMB1, Aspendale, VIC 3195, AustraliaClimate Research Centre, CSIRO, PMB1, Aspendale, VIC 3195, AustraliaClimate Research Centre, CSIRO, PMB1, Aspendale, VIC 3195, Australiaformerly at: Climate Research Centre, CSIRO, PMB1, Aspendale, VIC 3195, AustraliadeceasedEnvironmental Sciences, Macquarie University, NSW 2109, AustraliaOne of the key challenges in atmospheric chemistry is to reduce the uncertainty of biogenic volatile organic compound (BVOC) emission estimates from vegetation to the atmosphere. In Australia, eucalypt trees are a primary source of biogenic emissions, but their contribution to Australian air sheds is poorly quantified. The Model of Emissions of Gases and Aerosols from Nature (MEGAN) has performed poorly against Australian isoprene and monoterpene observations. Finding reasons for the MEGAN discrepancies and strengthening our understanding of biogenic emissions in this region is our focus. We compare MEGAN to the locally produced Australian Biogenic Canopy and Grass Emissions Model (ABCGEM), to identify the uncertainties associated with the emission estimates and the data requirements necessary to improve isoprene and monoterpene emissions estimates for the application of MEGAN in Australia. Previously unpublished, ABCGEM is applied as an online biogenic emissions inventory to model BVOCs in the air shed overlaying Sydney, Australia. The two models use the same meteorological inputs and chemical mechanism, but independent inputs of leaf area index (LAI), plant functional type (PFT) and emission factors. We find that LAI, a proxy for leaf biomass, has a small role in spatial, temporal and inter-model biogenic emission variability, particularly in urban areas for ABCGEM. After removing LAI as the source of the differences, we found large differences in the emission activity function for monoterpenes. In MEGAN monoterpenes are partially light dependent, reducing their dependence on temperature. In ABCGEM monoterpenes are not light dependent, meaning they continue to be emitted at high rates during hot summer days, and at night. When the light dependence of monoterpenes is switched off in MEGAN, night-time emissions increase by 90–100 % improving the comparison with observations, suggesting the possibility that monoterpenes emitted from Australian vegetation may not be as light dependent as vegetation globally. Targeted measurements of emissions from in situ Australian vegetation, particularly of the light dependence issue are critical to improving MEGAN for one of the world's major biogenic emitting regions.https://www.atmos-chem-phys.net/18/7539/2018/acp-18-7539-2018.pdf |
| spellingShingle | K. M. Emmerson M. E. Cope I. E. Galbally S. Lee S. Lee P. F. Nelson Isoprene and monoterpene emissions in south-east Australia: comparison of a multi-layer canopy model with MEGAN and with atmospheric observations Atmospheric Chemistry and Physics |
| title | Isoprene and monoterpene emissions in south-east Australia: comparison of a multi-layer canopy model with MEGAN and with atmospheric observations |
| title_full | Isoprene and monoterpene emissions in south-east Australia: comparison of a multi-layer canopy model with MEGAN and with atmospheric observations |
| title_fullStr | Isoprene and monoterpene emissions in south-east Australia: comparison of a multi-layer canopy model with MEGAN and with atmospheric observations |
| title_full_unstemmed | Isoprene and monoterpene emissions in south-east Australia: comparison of a multi-layer canopy model with MEGAN and with atmospheric observations |
| title_short | Isoprene and monoterpene emissions in south-east Australia: comparison of a multi-layer canopy model with MEGAN and with atmospheric observations |
| title_sort | isoprene and monoterpene emissions in south east australia comparison of a multi layer canopy model with megan and with atmospheric observations |
| url | https://www.atmos-chem-phys.net/18/7539/2018/acp-18-7539-2018.pdf |
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