L. J. Mickley

Harvard University, Cambridge, Massachusetts, United States

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Publications (81)208.45 Total impact

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    ABSTRACT: Fires associated with agricultural and plantation development in Indonesia impact ecosystem services and release emissions into the atmosphere that degrade regional air quality and contribute to greenhouse gas concentrations. In this study, we estimate the relative contributions of the oil palm, timber (for wood pulp and paper), and logging industries in Sumatra and Kalimantan to land cover change, fire activity, and regional population exposure to smoke concentrations. Concessions for these three industries cover 21% and 49% of the land area in Sumatra and Kalimantan respectively, with the highest overall area in lowlands on mineral soils instead of more carbon-rich peatlands. In 2012, most remaining forest area was located in logging concessions for both islands, and for all combined concessions, there was higher remaining lowland and peatland forest area in Kalimantan (45% and 46%, respectively) versus Sumatra (20% and 27%, respectively). Emissions from all combined concessions comprised 41% of total fire emissions (within and outside of concession boundaries) in Sumatra and 27% in Kalimantan for the 2006 burning season, which had high fire activity relative to decadal emissions. Most fire emissions were observed in concessions located on peatlands and non-forested lowlands, the latter of which could include concessions that are currently under production, cleared in preparation for production, or abandoned lands. For the 2006 burning season, timber concessions from Sumatra (47% of area and 88% of emissions) and oil palm concessions from Kalimantan (33% of area and 67% of emissions) contributed the most to concession-related fire emissions from each island. Although fire emissions from concessions were higher in Kalimantan, emissions from Sumatra contributed 63% of concession-related smoke concentrations for the population-weighted region because fire sources were located closer to population centers. In order to protect regional public health, our results highlight the importance of limiting the use of fire by the timber and oil palm industries, particularly on concessions that contain peatlands and non-forest, by such methods as improving monitoring systems, local-level management, and enforcement of existing fire bans.
    No preview · Article · Aug 2015 · Environmental Research Letters
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    ABSTRACT: Isoprene and its oxidation products are major players in the oxidative chemistry of the troposphere. Current understanding of the factors controlling biogenic isoprene emissions and of the fate of isoprene oxidation products in the atmosphere has been evolving rapidly. We use a climate–biosphere–chemistry modeling framework to evaluate the sensitivity of estimates of the tropospheric oxidative capacity to uncertainties in isoprene emissions and photochemistry. Our work focuses on two climate transitions: from the Last Glacial Maximum (LGM, 19 000–23 000 years BP) to the preindustrial (1770s) and from the preindustrial to the present day (1990s). We find that different oxidants have different sensitivities to the uncertainties tested in this study. Ozone is relatively insensitive, whereas OH is the most sensitive: changes in the global mean OH levels for the LGM-to-preindustrial transition range between −29 and +7 % and those for the preindustrial-to-present-day transition range between −8 and +17 % across our simulations. We find little variability in the implied relative LGM–preindustrial difference in methane emissions with respect to the uncertainties tested in this study. Conversely, estimates of the preindustrial-to-present-day and LGM-to-preindustrial changes in the global burden of secondary organic aerosol (SOA) are highly sensitive. We show that the linear relationship between tropospheric mean OH and tropospheric mean ozone photolysis rates, water vapor, and total emissions of NOx and reactive carbon – first reported in Murray et al. (2014) – does not hold across all periods with the new isoprene photochemistry mechanism. This study demonstrates how inadequacies in our current understanding of isoprene emissions and photochemistry impede our ability to constrain the oxidative capacities of the present and past atmospheres, its controlling factors, and the radiative forcing of some short-lived species such as SOA over time.
    Full-text · Article · Jul 2015 · Atmospheric Chemistry and Physics
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    Full-text · Dataset · Jul 2015
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    ABSTRACT: Records of ice-core nitrate and its isotopes hold the potential to assess past atmospheric conditions regarding NOx and oxidant levels. However, relating such records to past atmospheric conditions requires a site-specific understanding of the post-depositional processing of snow nitrate. We report δ15N(NO3-) records from the Greenland Ice Sheet Project 2 (GISP2) ice core over major climate transitions. Model calculations and comparison with records of parameters influencing UV-driven post-depositional processing of snow nitrate suggest that the observed variability in GISP2 δ15N(NO3-) over major climate transitions is primarily driven by changes in the degree of post-depositional loss of snow nitrate. Estimates of the fractional loss of snow nitrate is (16 - 23) % in the Holocene and (45 - 53) % in the glacial period, suggesting a (41 ± 32) % lower nitrate depositional flux to Greenland during the glacial period relative to the Holocene.
    Full-text · Article · Jun 2015 · Geophysical Research Letters
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    ABSTRACT: We estimate future area burned in Alaskan and Canadian forest by the midcentury (2046–2065) based on the simulated meteorology from 13 climate models under the A1B scenario. We develop ecoregion-dependent regressions using observed relationships between annual total area burned and a suite of meteorological variables and fire weather indices, and apply these regressions to the simulated meteorology. We find that for Alaska and western Canada almost all models predict significant (p < 0.05) increases in area burned at the midcentury, with median values ranging from 150 to 390%, depending on the ecoregion. Such changes are attributed to the higher surface air temperatures and 500 hPa geopotential heights relative to present day, which together lead to favorable conditions for wildfire spread. Elsewhere the model predictions are not as robust. For the central and southern Canadian ecoregions, the models predict increases in area burned of 45–90%. Except for the Taiga Plain, where area burned decreases by 50%, no robust trends are found in northern Canada, due to the competing effects of hotter weather and wetter conditions there. Using the GEOS-Chem chemical transport model, we find that changes in wildfire emissions alone increase mean summertime surface ozone levels by 5 ppbv for Alaska, 3 ppbv for Canada, and 1 ppbv for the western US by the midcentury. In the northwestern US states, local wildfire emissions at midcentury enhance surface ozone by an average of 1 ppbv, while transport of boreal fire pollution further degrades ozone air quality by an additional 0.5 ppbv. The projected changes in wildfire activity increase daily summertime surface ozone above the 95th percentile by 1 ppbv in the northwestern US, 5 ppbv in the high latitudes of Canada, and 15 ppbv in Alaska, suggesting a greater frequency of pollution episodes in the future atmosphere.
    Full-text · Article · May 2015 · Atmospheric Chemistry and Physics
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    Becky Alexander · Loretta J. Mickley
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    ABSTRACT: The oxidizing capacity of the atmosphere, defined as the global mean tropospheric abundance of the hydroxyl radical (OH∙), strongly influences air pollution by controlling the lifetimes of gaseous pollutants and the production of particulate matter. Predicting future changes in OH∙ due to anthropogenic emissions and climate change is of interest to air quality managers, but is difficult because of multiple competing effects. Models of atmospheric chemistry suggest that these competing effects buffer significant change in OH∙ in the past and in the near future. However, proxy-based observations for past changes in OH∙ and other oxidants over the preindustrial-industrial and glacial-interglacial time scales suggest much larger changes than models estimate. Model sensitivity studies show that variability in past and future OH∙ is highly sensitive to relative emissions of reactive nitrogen and carbon, water vapor, lightning, and stratospheric ozone, implying that one or more of these variables is highly sensitive to climate.
    Full-text · Article · May 2015
  • L. Shen · L. J. Mickley · A. P. K. Tai
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    ABSTRACT: We investigate the effect of synoptic-scale weather patterns on observed maximum daily 8 h average (MDA8) surface ozone over the eastern United States during 1980–2012 in summer (June–August, JJA). Zonally averaged, the SD of daily MDA8 JJA ozone shows a bimodal structure, with peaks at 30–35° N and 39–43° N, identifying those regions most influenced by daily weather variability. We apply Empirical Orthogonal Functions (EOFs) to understand the causes of this structure. The first three leading EOF patterns explain 53% of the total variance in deseasonalized surface ozone, displaying (1) a widespread decrease of ozone in the eastern United States associated with southward movement of jet wind, (2) a north–south pattern linked to the Bermuda High system when its west boundary is located along the East coast, and (3) an east–west pattern characteristic of a westward extension of Bermuda High and an enhanced Great Plains low level jet (GPLLJ). The northern peak of ozone SD can be explained by polar jet activity, while the southern peak appears related to variability in the Bermuda High and GPLLJ. In the Midwest and Northeast, we find that the correlation coefficient r between detrended mean JJA MDA8 ozone and the polar jet frequency ranges between −0.76 and −0.93 over 1980–2012 depending on the time period selected, suggesting that polar jet frequency could provide a simple metric to predict ozone variability in future climate regimes. In the Southeast, the influence of the Bermuda High on mean JJA MDA8 ozone depends on the location of its west edge. For those summers when the average position of the west edge is located west of ∼ 85.4° W, a westward shift in the Bermuda High west edge increases ozone in the Southeast by ∼ 1 ppbv deg-1 in longitude. For all summers, a northward shift in the Bermuda High west edge increases ozone over the entire eastern United States by 1–2 ppbv deg-1 in latitude. None of the synoptic patterns identified in this study show a significant trend from 1980 to 2012, confirming that the observed ozone decrease over the eastern United States during this time period is mainly caused by emission controls.
    No preview · Article · May 2015 · Atmospheric Chemistry and Physics
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    ABSTRACT: Fire emissions associated with land cover change and land management contribute to the concentrations of atmospheric pollutants, which can affect regional air quality and climate. Mitigating these impacts requires a comprehensive understanding of the relationship between fires and different land cover change trajectories and land management strategies. We develop future fire emissions inventories from 2010–2030 for Sumatra and Kalimantan (Indonesian Borneo) to assess the impact of varying levels of forest and peatland conservation on air quality in Equatorial Asia. To compile these inventories, we combine detailed land cover information from published maps of forest extent, satellite fire radiative power observations, fire emissions from the Global Fire Emissions Database, and spatially explicit future land cover projections using a land cover change model. We apply the sensitivities of mean smoke concentrations to Indonesian fire emissions, calculated by the GEOS-Chem adjoint model, to our scenario-based future fire emissions inventories to quantify the different impacts of fires on surface air quality across Equatorial Asia. We find that public health impacts are highly sensitive to the location of fires, with emissions from Sumatra contributing more to smoke concentrations at population centers across the region than Kalimantan, which had higher emissions by more than a factor of two. Compared to business-as-usual projections, protecting peatlands from fires reduces smoke concentrations in the cities of Singapore and Palembang by 70% and 40%, and by 60% for the Equatorial Asian region, weighted by the population in each grid cell. Our results indicate the importance of focusing conservation priorities on protecting both forested (intact or logged) peatlands and non-forested peatlands from fire, even after considering potential leakage of deforestation pressure to other areas, in order to limit the impact of fire emissions on atmospheric smoke concentrations and subsequent health effects.
    No preview · Article · May 2015 · Environmental Research Letters
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    ABSTRACT: Satellite observations of formaldehyde (HCHO) columns provide top-down constraints on emissions of highly reactive volatile organic compounds (HRVOCs). This approach has been used previously in the US to estimate isoprene emissions from vegetation, but application to anthropogenic emissions has been stymied by lack of a discernable HCHO signal. Here we show that temporal oversampling of HCHO data from the Ozone Monitoring Instrument (OMI) for 2005–2008 enables detection of urban and industrial plumes in eastern Texas including Houston, Port Arthur, and Dallas/Fort Worth. By spatially integrating the HCHO enhancement in the Houston plume observed by OMI we estimate an anthropogenic HCHO source of 250 ± 140 kmol h−1. This implies that anthropogenic HRVOC emissions in Houston are 4.8 ± 2.7 times higher than reported by the US Environmental Protection Agency inventory, and is consistent with field studies identifying large ethene and propene emissions from petrochemical industrial sources.
    Full-text · Article · Nov 2014 · Environmental Research Letters
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    ABSTRACT: Indonesia has experienced rapid land use change over the last few decades as forests and peatswamps have been cleared for more intensively managed land uses, including oil palm and timber plantations. Fires are the predominant method of clearing and managing land for more intensive uses, and the related emissions affect public health by contributing to regional particulate matter and ozone concentrations and global atmospheric carbon dioxide concentrations. Here, we examine emissions from fires associated with land use clearing and land management on the Indonesian island of Sumatra and the sensitivity of this fire activity to interannual meteorological variability. We find ~80% of 2005 to 2009 Sumatra emissions are associated with degradation or land use maintenance instead of immediate land use conversion, especially in dry years. We estimate Sumatra fire emissions from land use change and maintenance for the next two decades with five scenarios of land use change, the Global Fire Emissions Database Version 3, detailed 1-km2 land use change maps, and MODIS fire radiative power observations. Despite comprising only 16% of the original study area, we predict that 37-48% of future Sumatra emissions from land use change will occur in fuel-rich peatswamps unless this land cover type is protected effectively. This result means that the impact of fires on future air quality and climate in Equatorial Asia will be decided in part by the conservation status given to the remaining peatswamps on Sumatra. Results from this paper will be implemented in an atmospheric transport model to quantify the public health impacts from the transport of fire emissions associated with future land use scenarios in Sumatra.This article is protected by copyright. All rights reserved.
    Full-text · Article · Jul 2014 · Global Change Biology
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    ABSTRACT: Radiative forcing by aerosols and tropospheric ozone could play a significant role in recent Arctic warming. These species are in general poorly accounted for in climate models. We use the GEOS-Chem global chemical transport model to construct a 3-D representation of Arctic aerosols and ozone that is consistent with observations and can be used in climate simulations. We focus on 2008, when extensive observations were made from different platforms as part of the International Polar Year. Comparison to aircraft (ARCTAS), surface, and ship cruise (ICEALOT, ASCOS) observations suggests that GEOS-Chem provides in general a successful year-round simulation of Arctic black carbon (BC), organic carbon (OC), sulfate, and dust aerosol. BC has major fuel combustion and boreal fire sources, OC is mainly from fires, sulfate has a mix of anthropogenic and natural sources, and dust is mostly from the Sahara. The model is successful in simulating aerosol optical depth (AOD) observations from AERONET stations in the Arctic; the sharp drop from spring to summer appears driven in part by the smaller size of sulfate aerosol in summer. The anthropogenic contribution to Arctic AOD is a factor of 4 larger in spring than summer and is mainly sulfate. Simulation of absorbing aerosol optical depth (AAOD) indicates that non-BC aerosol (OC and dust) contributed 24% of Arctic AAOD at 550 nm and 37% of absorbing mass deposited to the snow pack in 2008. Open fires contributed half of AAOD at 550 nm and half of deposition to the snowpack.
    No preview · Article · Apr 2014
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    ABSTRACT: The oxidative capacity of past atmospheres is highly uncertain. We present here a new climate-biosphere-chemistry modeling framework to determine oxidant levels in the present and past troposphere. We use the GEOS-Chem chemical transport model driven by meteorological fields from the NASA Goddard Institute of Space Studies (GISS) ModelE, with land cover and fire emissions from dynamic global vegetation models. We present time-slice simulations for the present day, late preindustrial era (AD 1770), and the Last Glacial Maximum (LGM, 19-23 ka), and we test the sensitivity of model results to uncertainty in lightning and fire emissions. We find that most preindustrial and paleo climate simulations yield reduced oxidant levels relative to the present day. Contrary to prior studies, tropospheric mean OH in our ensemble shows little change at the LGM relative to the preindustrial era (0.5 ± 12 %), despite large reductions in methane concentrations. We find a simple linear relationship between tropospheric mean ozone photolysis rates, water vapor, and total emissions of NOx and reactive carbon that explains 72 % of the variability in global mean OH in 11 different simulations across the last glacial-interglacial time interval and the industrial era. Key parameters controlling the tropospheric oxidative capacity over glacial-interglacial periods include overhead stratospheric ozone, tropospheric water vapor, and lightning NOx emissions. Variability in global mean OH since the LGM is insensitive to fire emissions. Our simulations are broadly consistent with ice-core records of Δ17O in sulfate and nitrate at the LGM, and CO, HCHO, and H2O2 in the preindustrial era. Our results imply that the glacial-interglacial changes in atmospheric methane observed in ice cores are predominantly driven by changes in its sources as opposed to its sink with OH.
    Full-text · Article · Mar 2014 · Atmospheric Chemistry and Physics
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    Xu Yue · Loretta J. Mickley · Jennifer A. Logan
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    ABSTRACT: We estimate area burned in southern California at mid-century (2046–2065) for the Intergovernmental Panel on Climate Change A1B scenario. We develop both regressions and a parameterization to predict area burned in three ecoregions, and apply present-day (1981–2000) and future meteorology from the suite of general circulation models to these fire prediction tools. The regressions account for the impacts of both current and antecedent meteorological factors on wildfire activity and explain 40–46 % of the variance in area burned during 1980–2009. The parameterization yields area burned as a function of temperature, precipitation, and relative humidity, and includes the impact of Santa Ana wind and other geographical factors on wildfires. It explains 38 % of the variance in area burned over southern California as a whole, and 64 % of the variance in southwestern California. The parameterization also captures the seasonality of wildfires in three ecoregions of southern California. Using the regressions, we find that area burned likely doubles in Southwestern California by midcentury, and increases by 35 % in the Sierra Nevada and 10 % in central western California. The parameterization suggests a likely increase of 40 % in area burned in southwestern California and 50 % in the Sierra Nevada by midcentury. It also predicts a longer fire season in southwestern California due to warmer and drier conditions on Santa Ana days in November. Our method provides robust estimates of area burned at midcentury, a key metric which can be used to calculate the fire-related effects on air quality, human health, and the associated costs.
    Full-text · Article · Feb 2014 · Climate Dynamics
  • L.J. Mickley · A.M. Fiore · D.K. Henze
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    ABSTRACT: An overview of AQAST activities examining the interactions between climate change and U.S. air quality. These activities utilize Earth System data and models, in addition to satellite observations.
    No preview · Article · Feb 2014 · EM: Air and Waste Management Association's Magazine for Environmental Managers
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    Jinping Tang · Pucai Wang · Loretta J. Mickley · Xiangao Xia · Hong Liao · Xu Yue · Li Sun · Junrong Xia
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    ABSTRACT: Correlations between water cloud effective radius (CER) and aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS) are examined over seven sub-regions in Eastern China for 2003–2012. Water phase cloud is defined as having a cloud top pressure greater than 800 hPa. Significant negative correlation coefficients (r = −0.79 ∼ −0.94) between AOD and CER are derived over the East Sea and the South China Sea for grid cells with AOD < 0.3. However, positive correlations (r = 0.01–0.91) are calculated for cells with AOD > 0.3. In contrast, significant positive correlations (r = 0.67–0.95) are derived over the Eastern China mainland and Yellow Sea. Further analysis for North China Plain shows that variations in wind speed and relative humidity may account for such positive correlations. Southerly winds carry high levels of pollutants and abundant water vapor, resulting in coincident increases in both AOD and CER in North China Plain, while the northerly winds transport dry and clean air from high latitudes, leading to decreases in AOD and CER. Both processes contribute to the positive correlations between AOD and CER over Eastern China, suggesting that the influence of background weather conditions need to be considered when studying the interactions between aerosol and cloud.
    Full-text · Article · Feb 2014 · Atmospheric Environment
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    ABSTRACT: High smoke concentrations in Equatorial Asia, primarily from land conversion to oil palm plantations, affect a densely populated region and represent a serious but poorly quantified air quality concern. Continued expansion of the oil palm industry is expected but the resulting population exposure to smoke is highly dependent on where this expansion takes place. We use the adjoint of the GEOS-Chem chemical transport model to map the sensitivity of smoke concentrations in major Equatorial Asian cities, and for the population-weighted region, to the locations of the fires. We find that fires in southern Sumatra are particularly detrimental, and that a land management policy protecting peatswamp forests in Southeast Sumatra would be of great air quality benefit. Our adjoint sensitivities can be used to immediately infer population exposure to smoke for any future fire emission scenario.
    Full-text · Article · Jan 2014 · Atmospheric Environment
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    Xu Yue · Loretta J Mickley · Jennifer A Logan · Jed O Kaplan
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    ABSTRACT: We estimate future wildfire activity over the western United States during the mid-21(st) century (2046-2065), based on results from 15 climate models following the A1B scenario. We develop fire prediction models by regressing meteorological variables from the current and previous years together with fire indexes onto observed regional area burned. The regressions explain 0.25-0.60 of the variance in observed annual area burned during 1980-2004, depending on the ecoregion. We also parameterize daily area burned with temperature, precipitation, and relative humidity. This approach explains ~0.5 of the variance in observed area burned over forest ecoregions but shows no predictive capability in the semi-arid regions of Nevada and California. By applying the meteorological fields from 15 climate models to our fire prediction models, we quantify the robustness of our wildfire projections at mid-century. We calculate increases of 24-124% in area burned using regressions and 63-169% with the parameterization. Our projections are most robust in the southwestern desert, where all GCMs predict significant (p<0.05) meteorological changes. For forested ecoregions, more GCMs predict significant increases in future area burned with the parameterization than with the regressions, because the latter approach is sensitive to hydrological variables that show large inter-model variability in the climate projections. The parameterization predicts that the fire season lengthens by 23 days in the warmer and drier climate at mid-century. Using a chemical transport model, we find that wildfire emissions will increase summertime surface organic carbon aerosol over the western United States by 46-70% and black carbon by 20-27% at midcentury, relative to the present day. The pollution is most enhanced during extreme episodes: above the 84(th) percentile of concentrations, OC increases by ~90% and BC by ~50%, while visibility decreases from 130 km to 100 km in 32 Federal Class 1 areas in Rocky Mountains Forest.
    Full-text · Article · Oct 2013 · Atmospheric Environment
  • Yuxuan Wang · Lulu Shen · Shiliang Wu · Loretta Mickley · Jingwei He · Jiming Hao
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    ABSTRACT: We use a global chemical transport model (GEOS-Chem) driven by the GISS GCM to investigate the effect on China's surface ozone from 2000 to 2050 global changes in climate and anthropogenic emissions as projected by the IPCC A1B scenario, with a focus on the different response between East and West China where present-day anthropogenic emissions, natural conditions, and ozone source attributions differ significantly. Over East China, climate change will increase both surface ozone and the possibility of high ozone episodes, implying a significant ‘climate change penalty’ that can be attributed mainly to increasing biogenic emissions of volatile organic compounds (VOCs). Over West China on the other hand, climate change will decrease mean surface ozone as a result of an increased ozone destruction rate in low-NOx regimes, assuming constant stratosphere–troposphere exchange (STE) of ozone. Chinese emissions change in 2050 will enlarge the East–West ozone difference in China, but emissions change from the rest of the world (excluding China) will decrease it. Driven by climate change and emissions change in combination, nation-mean surface ozone will increase, whereas East–West ozone contrast will decrease. In the future climate, the sensitivity of surface ozone to a given change in Chinese emissions will decrease over West China due to the accelerated ozone destruction rate and reduced transport from East China, but increase over East China as a result of the coupling effect between anthropogenic NOx and biogenic VOCs. The latter result suggests that the emission controls over East China need to be more aggressive in future climate.
    No preview · Article · Aug 2013 · Atmospheric Environment
  • Amos P. K. Tai · Loretta J. Mickley · Colette L. Heald · Shiliang Wu
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    ABSTRACT: [1] The inhibition of biogenic isoprene emission by elevated CO2 as observed in many plant taxa may significantly alter the sensitivity of air quality to global changes. We use a one-way coupled modeling framework to perform simulations under various combinations of 2000 to 2050 changes in climate, natural vegetation, anthropogenic emissions and land use to examine the effect of the CO2-isoprene interaction on atmospheric composition. We find that consideration of CO2 inhibition substantially reduces the sensitivity of surface ozone and secondary organic aerosol (SOA) to climate and natural vegetation, resulting in much smaller ozone and SOA increases in major populated regions than are projected by previous studies. The impact of land use on air quality is relatively insensitive to CO2 inhibition, rendering land use change the key factor that can offset or enhance the effects of anthropogenic emissions and shape air quality and climate-relevant species in the mid-21st century.
    No preview · Article · Jul 2013
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    H. Jiang · H. Liao · H. O. T. Pye · S. Wu · L. J. Mickley · J. H. Seinfeld · X. Y. Zhang
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    ABSTRACT: We investigate the 2000-2050 changes in concentrations of aerosols in China and the associated transboundary aerosol transport by using the chemical transport model GEOS-Chem driven by the Goddard Institute for Space Studies (GISS) general circulation model (GCM) 3 at 4° × 5° resolution. Future changes in climate and emissions projected by the IPCC A1B scenario are imposed separately and together through sensitivity simulations. Accounting for sulfate, nitrate, ammonium, black carbon (BC), and organic carbon (OC) aerosols, concentrations of individual aerosol species change by -2.3 to +1.7 μg m-3 and PM2.5 levels are projected to change by about 10-20% in eastern China as a result of 2000-2050 change in climate alone. With future changes in anthropogenic emissions alone, concentrations of sulfate, BC, and OC are simulated to decrease because of reductions in emissions, and those of nitrate are predicted to increase because of higher NOx emissions combined with decreases in sulfate. The net result is a reduction of seasonal mean PM2.5 concentrations in eastern China by 2-9.5 μg m-3 (or 10-30%) over 2000-2050. It is noted that current emission inventories for BC and OC over China are found to be inadequate at present. Transboundary fluxes of different aerosol species show different sensitivities to future changes in climate and emissions. The annual outflow of PM2.5 from eastern China to the western Pacific is estimated to change by -6.0%, -1.5%, and -9.0% over 2000-2050 owing to climate change alone, changes in emissions alone, and changes in both climate and emissions, respectively. The fluxes of nitrate and ammonium aerosols from Europe and Central Asia into western China increase over 2000-2050 by changes in emissions, leading to a 15% increase in annual inflow of PM2.5 to western China with future changes in both emissions and climate. Fluxes of BC and OC from South Asia to China in spring contribute to a large fraction of the annual inflow of PM2.5. The annual inflow of PM2.5 from South Asia and Southeast Asia to China is estimated to change by -55%, +133%, and +63% over 2000-2050 owing to climate change alone, changes in emissions alone, and changes in both climate and emissions, respectively. While the 4° × 5° spatial resolution is a limitation of the present study, the direction of predicted changes in aerosol levels and transboundary fluxes still provides valuable insight into future air quality.
    Preview · Article · Mar 2013 · Atmospheric Chemistry and Physics

Publication Stats

4k Citations
208.45 Total Impact Points

Institutions

  • 2000-2015
    • Harvard University
      • • School of Engineering and Applied Sciences
      • • Department of Earth and Planetary Sciences
      Cambridge, Massachusetts, United States
  • 1999
    • Space Studies Institute
      MHV, California, United States