A global model study of the impact of land-use change in Borneo on atmospheric composition

Warwick, N. J.; Archibald, Alexander T.; Ashworth, Kirsti; Dorsey, J. R.; Edwards, P. M.; Heard, Dwayne E.; Langford, B.; Lee, James; Misztal, Pawel K.; Whalley, Lisa K.; Pyle, J. A.

doi:10.5194/acp-13-9183-2013

Cited by 21 publications

(48 citation statements)

References 55 publications

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“…Figure 10 shows that OH in CheT2 is indeed higher than in CheT over the main isoprene emitting regions, with maximum increases of approximately 50 %. Warwick et al (2013) also calculated that including the Peeters mechanism in UM-UKCA gave higher OH, improving agreement between modelled and measured values.…”

Section: Atmosmentioning

confidence: 99%

“…Proposals have been put forward for missing mechanistic pathways, e.g. peroxy radical isomerisation (Peeters et al, 2009), and epoxide formation (Paulot et al, 2009) which to some extent reconcile these discrepancies (Archibald et al, 2010a;Warwick et al, 2013;Fuchs et al, 2013). It has also been demonstrated that positive biases in the measurement of HO 2 (Fuchs et al, 2011) and OH (Mao et al, 2012) cannot be ruled out in some of those field campaigns listed above.…”

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confidence: 99%

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Influence of isoprene chemical mechanism on modelled changes in tropospheric ozone due to climate and land use over the 21st century

et al. 2015

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Abstract. Isoprene is a precursor to tropospheric ozone, a key pollutant and greenhouse gas. Anthropogenic activity over the coming century is likely to cause large changes in atmospheric CO 2 levels, climate and land use, all of which will alter the global vegetation distribution leading to changes in isoprene emissions. Previous studies have used global chemistry-climate models to assess how possible changes in climate and land use could affect isoprene emissions and hence tropospheric ozone. The chemistry of isoprene oxidation, which can alter the concentration of ozone, is highly complex, therefore it must be parameterised in these models. In this work, we compare the effect of four different reduced isoprene chemical mechanisms, all currently used in Earth system models, on tropospheric ozone. Using a box model we compare ozone in these reduced schemes to that in a more explicit scheme (the Master Chemical Mechanism) over a range of NO x and isoprene emissions, through the use of O 3 isopleths. We find that there is some variability, especially at high isoprene emissions, caused by differences in isoprene-derived NO x reservoir species. A global model is then used to examine how the different reduced schemes respond to potential future changes in climate, isoprene emissions, anthropogenic emissions and land use change. We find that, particularly in isoprene-rich regions, the response of the schemes varies considerably. The wide-ranging response is due to differences in the model descriptions of the peroxy radical chemistry, particularly their relative rates of reaction towards NO, leading to ozone formation, or HO 2 , leading to termination. Also important is the yield of isoprene nitrates and peroxyacyl nitrate precursors from isoprene oxidation. Those schemes that produce less of these NO x reservoir species, tend to produce more ozone locally and less away from the source region. We also note changes in other key oxidants such as NO 3 and OH (due to the inclusion of additional isoprene-derived HO x recycling pathways). These have implications for secondary organic aerosol formation, as does the inclusion of an epoxide formation pathway in one of the mechanisms. By combining the emissions and O 3 data from all of the global model integrations, we are able to construct isopleth plots comparable to those from the box model analysis. We find that the global and box model isopleths show good qualitative agreement, suggesting that comparing chemical mechanisms with a box model in this framework is a useful tool for assessing mechanistic performance in complex global models. We conclude that as the choice of reduced isoprene mechanism may alter both the magnitude and sign of the ozone response, how isoprene chemistry is parameterised in perturbation experiments such as these is a crucially important consideration. More measurements and laboratory studies are needed to validate these reduced mechanisms especially under high-volatile-organiccompound, low-NO x conditions.

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Section: Atmosmentioning

confidence: 99%

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confidence: 99%

Influence of isoprene chemical mechanism on modelled changes in tropospheric ozone due to climate and land use over the 21st century

et al. 2015

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“…We do not attempt to model the detailed growth, harvesting, and senescence history of the plantation (Fan et al, 2015). Previous studies (Ashworth et al, 2012, andWarwick et al, 2013) did not explicitly simulate the concomitant changes to deposition due to oil palm expansion. They instead performed short sensitivity studies wherein Warwick et al (2013) doubled the modeled deposition velocities, and Ashworth et al (2012) scaled modeled deposition parameters (roughness length and LAI) by observed canopy height and biomass density.…”

Section: Description Of Sea Land Usementioning

confidence: 99%

“…The basal isoprene emission factor of oil palm is set to the basal rate of 7.8 mg m −2 h −1 measured during OP3 ; this basal emission factor is modulated online by local meteorology and phenology to estimate emissions. Previous studies scaled modeled emissions of broadleaf evergreen trees (Ashworth et al, 2012), or kept these emissions fixed to the measured rate during OP3 (Warwick et al, 2013). The basal isoprene emission factor of the native forests (considered to be broadleaf evergreen tropical trees) is reduced to 1.6 mg m −2 h −1 to match the OP3 measurements , which is a factor of 4 lower than the emission factors for broadleaf evergreen tropical trees within MEGANv2.1, and consistent with the rainforests of Southeast Asia emitting less isoprene than South American and African rainforests.…”

Section: Description Of Sea Land Usementioning

confidence: 99%

“…Warwick et al (2013) simulate the influence of modern-day oil palm distributions over Borneo, constraining both isoprene and NO 2 fluxes to values measured during the OP3 campaign, and converting the entire island of Borneo to oil palm plantations. They find the potential for up to 70 % (30-45 ppbv) increases in regional O 3 concentrations.…”

Section: Introductionmentioning

confidence: 99%

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Impacts of current and projected oil palm plantation expansion on air quality over Southeast Asia

et al. 2016

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Abstract. Over recent decades oil palm plantations have rapidly expanded across Southeast Asia (SEA). According to the United Nations, oil palm production in SEA increased by a factor of 3 from 1995 to 2010. We investigate the impacts of current (2010) and near-term future (2020) projected oil palm expansion in SEA on surface-atmosphere exchange and the resulting air quality in the region. For this purpose, we use satellite data, high-resolution land maps, and the chemical transport model GEOS-Chem. Relative to a no oil palm plantation scenario ( ∼ 1990), overall simulated isoprene emissions in the region increased by 13 % due to oil palm plantations in 2010 and a further 11 % in the near-term future. In addition, the expansion of palm plantations leads to local increases in ozone deposition velocities of up to 20 %. The net result of these changes is that oil palm expansion in SEA increases surface O 3 by up to 3.5 ppbv over dense urban regions, and in the near-term future could rise more than 4.5 ppbv above baseline levels. Biogenic secondary organic aerosol loadings also increase by up to 1 µg m −3 due to oil palm expansion, and could increase by a further 2.5 µg m −3 in the near-term future. Our analysis indicates that while the impact of recent oil palm expansion on air quality in the region has been significant, the retrieval error and sensitivity of the current constellation of satellite measurements limit our ability to observe these impacts from space. Oil palm expansion is likely to continue to degrade air quality in the region in the coming decade and hinder efforts to achieve air quality regulations in major urban areas such as Kuala Lumpur and Singapore.

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Sea salt as an ice core proxy for past sea ice extent: A process‐based model study

et al. 2014

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Sea ice is a reflection of, and a feedback on, the Earth's climate. We explore here, using a global atmospheric chemistry-transport model, the use of sea salt in Antarctic ice cores to obtain continuous long-term, regionally integrated records of past sea ice extent, synchronous with ice core records of climate. The model includes the production, transport, and deposition of sea salt aerosol from the open ocean and "blowing snow" on sea ice. Under current climate conditions, we find that meteorology, not sea ice extent, is the dominant control on the atmospheric concentration of sea salt reaching coastal and continental Antarctic sites on interannual timescales. However, through a series of idealized sensitivity experiments, we demonstrate that sea salt has potential as a proxy for larger changes in sea ice extent (e.g., glacial-interglacial). Treating much of the sea ice under glacial conditions as a source of salty blowing snow, we demonstrate that the increase in sea ice extent alone (without changing the meteorology) could drive, for instance, a 68% increase in atmospheric sea salt concentration at the site of the Dome C ice core, which exhibits an approximate twofold glacial increase in sea salt flux. We also show how the sensitivity of this potential proxy decreases toward glacial sea ice extent-the basis of an explanation previously proposed for the lag observed between changes in sea salt flux and δD (an ice core proxy for air temperature) at glacial terminations. The data thereby permit simultaneous changes in sea ice extent and climate.

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A global model study of the impact of land-use change in Borneo on atmospheric composition

Cited by 21 publications

References 55 publications

Influence of isoprene chemical mechanism on modelled changes in tropospheric ozone due to climate and land use over the 21st century

Influence of isoprene chemical mechanism on modelled changes in tropospheric ozone due to climate and land use over the 21st century

Impacts of current and projected oil palm plantation expansion on air quality over Southeast Asia

Sea salt as an ice core proxy for past sea ice extent: A process‐based model study

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