Proceedings of the 4th International Conference on Transport, Atmosphere and Climate

The "4th International Conference on Transport, Atmosphere and Climate (TAC-4)" held in Bad Kohlgrub (Germany), 2015, was organised with the objective of updating our knowledge on the impacts of transport on the composition of the atmosphere and on climate, three years after the TAC-3 conference in Prien am Chiemsee (Germany). The TAC-4 conference covered all aspects of the impact of the different modes of transport (aviation, road transport, shipping etc.) on atmospheric chemistry, microphysics, radiation and climate, in particular

Spatial and temporal distribution of tropospheric ozone over Southern Africa

Student Number: 0201936W - MSc research report - School of Geography, Archaeology and Environmental Sciences - Faculty of ScienceTropospheric ozone over southern Africa is characterised using the Southern Africa Regional Science Initiative (SAFARI) 2000 aircraft datasets collected from surface to just above the boundary layer, and satellite remotely sensed ozone column depth. Ozonesonde datasets for Irene, South Africa; Lusaka, Zambia; Nairobi and Malindi, both Kenyan stations were, used to supplement the aircraft and satellite data. The period studied is the dry biomass burning season between August and September, 2000 Source areas of ozone precursors have been identified by trajectory analysis. Fivepoint, back trajectory clusters in the region reveal well-defined air mass transport corridors. Enhanced ozone concentrations, above 70 ppb, were regularly encountered in the lower troposphere (3.5 km above ground level) in air masses distributed over the sub-region by distinct re-circulation pathways, which prevailed during the study period. Occasional, episodes of significant higher ozone pollution, above 100 ppbv are identified. Savannah fire products transported from seasonal biomass burning regions of western Zambia, northern Zimbabwe and Mozambique have been found to be the major sources of ozone pollution over the sub-region. Another source, though on a lesser scale, is the Highveld industrial region of South Africa. In situ air observations established that the western and eastern sectors of the southern Africa, north of 23°S latitude, were the major sources of regional ozone precursor gases. The regions southwards of 23°S were observed to have lower ozone pollution

Air quality during the 2008 Beijing Olympics : secondary pollutants and regional impact

Author name used in this publication: Wang T.Author name used in this publication: Nie, W.Author name used in this publication: Gao, J.Author name used in this publication: Xue, L. K.Author name used in this publication: Gao, X. M.Author name used in this publication: Wang, X. F.Author name used in this publication: Qiu, J.Author name used in this publication: Poon, C. N.Author name used in this publication: Meinardi, S.Author name used in this publication: Blake, D.Author name used in this publication: Wang, S. L.Author name used in this publication: Ding, A. J.Author name used in this publication: Chai, F. H.Author name used in this publication: Zhang, Q. Z.Author name used in this publication: Wang, W. X.2010-2011 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Forward and Inverse Analysis of Chemical Transport Models

Assessing the discrepancy between modeled and observed distributions of aerosols is a persistent problem on many scales. Tools for analyzing the evolution of aerosol size distributions using the adjoint method are presented in idealized box model calculations. The ability to recover information about aerosol growth rates and initial size distributions is assessed given a range of simulated observations of evolving systems. While such tools alone could facilitate analysis of chamber measurements, improving estimates of aerosol sources on regional and global scales requires explicit consideration of many additional chemical and physical processes that govern secondary formation of atmospheric aerosols from emissions of gas-phase precursors. The adjoint of the global chemical transport model GEOS-Chem is derived, affording detailed analysis of the relationship between gas-phase aerosol precursor emissions (SOx, NOx, and NH3) and the subsequent distributions of sulfate - ammonium - nitrate aerosol. Assimilation of surface measurements of sulfate and nitrate aerosol is shown to provide valuable constraints on emissions of ammonia. Adjoint sensitivities are used to propose strategies for air quality control, suggesting, for example, that reduction of SOx emissions in the summer and NH3 emissions in the winter would most effectively reduce non-attainment of aerosol air quality standards. The ability of this model to estimate global distributions of carbonaceous aerosol is also addressed. Based on new yield data from environmental chamber studies, mechanisms for incorporating the dependence of secondary organic aerosol (SOA) formation on NOx concentrations are developed for use in global models. When NOx levels are appropriately accounted for, it is demonstrated that sources such as isoprene and aromatics, previously neglected as sources of aerosol in global models, significantly contribute to predicted SOA burdens downwind of polluted areas (owing to benzene and toluene) and in the free troposphere (owing to isoprene)

Assessment of Biomass Burning and Mineral Dust Impacts on Air Quality and Regional Climate

East Asia is frequently influenced by dust storms and biomass burning. This study conducts a comprehensive investigation of its kind based on data analysis with surface measurements, satellite products, and model simulations. The objective of this study is to improve the understanding of the impacts of biomass burning and dust on air quality and regional climate. The study period covers March and April from 2006 to 2010. Biomass burning from Peninsular Southeast Asia (PSEA) has significant annual variations by up to 60% within the study period. The impact of biomass burning on air quality is mainly confined within the upper air due to the uplift motion driven by lee-side trough along eastern side of Tibet Plateau. The Weather Research and Forecasting and Community Multiscale Air Quality (WRF/CMAQ) system successfully reproduces the spatial distributions and temporal variations of air pollutants. Simulation bias falls in the range of 10%~50%, mainly due to the uncertainties within the emission inventory. This study reveals that the default WRF/CMAQ model has doubt counting of the soil moisture effect and subsequently underestimates dust emission by 55%. The microphysical parameterization and the speciation profile are revised to characterize the emission and mass contribution of dust better. Heterogeneous dust chemistry is also incorporated. These modifications substantially improve the model performance as indicated by the comparison between model simulations and observations. This study reveals that biomass burning has significant warming effect due to the presence of the underlying stratocumulus cloud. Biomass burning aerosol cools the near surface air by -0.2K, and significantly warms the upper air by up to +2K. Dust aerosol cools the near surface air by -0.9K and warms the upper air by +0.1K. This is the first investigation into the coexistence of biomass burning and dust over East Asia. This coexistence changes the aerosol direct radiative effect efficiencies of both biomass burning and dust by ±10%

Occurrence and fate of semivolatile organic compounds (SVOCs) in the tropical atmosphere

Ph.DDOCTOR OF PHILOSOPH

Development of measurement and modeling techniques to quantify atmospheric deposition of persistent, bioaccumulative and toxic chemicals in the Great Lakes

Measurement and modeling techniques were developed to improve over-water gaseous air-water exchange measurements for persistent bioaccumulative and toxic chemicals (PBTs). Analytical methods were applied to atmospheric measurements of hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). Additionally, the sampling and analytical methods are well suited to study semivolatile organic compounds (SOCs) in air with applications related to secondary organic aerosol formation, urban, and indoor air quality. A novel gas-phase cleanup method is described for use with thermal desorption methods for analysis of atmospheric SOCs using multicapillary denuders. The cleanup selectively removed hydrogen-bonding chemicals from samples, including much of the background matrix of oxidized organic compounds in ambient air, and thereby improved precision and method detection limits for nonpolar analytes. A model is presented that predicts gas collection efficiency and particle collection artifact for SOCs in multicapillary denuders using polydimethylsiloxane (PDMS) sorbent. An approach is presented to estimate the equilibrium PDMS-gas partition coefficient (Kpdms) from an Abraham solvation parameter model for any SOC. A high flow rate (300 L min-1) multicapillary denuder was designed for measurement of trace atmospheric SOCs. Overall method precision and detection limits were determined using field duplicates and compared to the conventional high-volume sampler method. The high-flow denuder is an alternative to high-volume or passive samplers when separation of gas and particle-associated SOCs upstream of a filter and short sample collection time are advantageous. A Lagrangian internal boundary layer transport exchange (IBLTE) Model is described. The model predicts the near-surface variation in several quantities with fetch in coastal, offshore flow: 1) modification in potential temperature and gas mixing ratio, 2) surface fluxes of sensible heat, water vapor, and trace gases using the NOAA COARE Bulk Algorithm and Gas Transfer Model, 3) vertical gradients in potential temperature and mixing ratio. The model was applied to interpret micrometeorological measurements of air-water exchange flux of HCB and several PCB congeners in Lake Superior. The IBLTE Model can be applied to any scalar, including water vapor, carbon dioxide, dimethyl sulfide, and other scalar quantities of interest with respect to hydrology, climate, and ecosystem science

Atmospheric Mercury

Mercury is a serious environmental toxin that is distributed globally by large-scale atmospheric circulations. The chapters in this book cover measurements of speciated atmospheric mercury, regional modeling, continental-scale distributions across the U.S. and Canada, large-scale distributions in the free troposphere, and changes in wet deposition across the U.S. The diverse topics give snap-shots of current research areas in atmospheric mercury and some insight into policy issues in Europe. Together, the work demonstrates the complexity of atmospheric mercury and provides aspects on measuring and modeling it. Much work is needed in the future to unravel the chemical forms of oxidized atmospheric mercury and how it is intertwined in global cycling of mercury. The complexities of this work are extremely challenging for emerging atmospheric chemists

Ambient Air Quality in the Czech Republic

Ambient air quality in the present-day Czech Republic (CR), one of the two succession countries of Czechoslovakia post-1993, was perceived as a major problem with severe human health and environmental consequences, particularly between the 1970s and 1990s. Since that time, the ambient air quality in the CR has improved substantially, due to newly introduced stringent legislation and technical countermeasures. Nevertheless, there are still activities which represent significant emission sources, such as local heating and increased vehicle travel through communities. After a substantial decrease in emissions in both the CR and its neighbouring countries, the levels of some ambient air pollutants from the 2000s are still not satisfactory. In this respect, aerosol, ground-level ozone, and benzo[a]pyrene remain major problems, as they do elsewhere in Europe. The book provides a valuable update both on time trends and spatial changes in ambient air quality, and highlights the recent activities in both monitoring and modelling of principle ambient air pollutants in the CR

Air Quality Monitoring, Assessment and Management

Human beings need to breathe oxygen diluted in certain quantity of inert gas for living. In the atmosphere, there is a gas mixture of, mainly, oxygen and nitrogen, in appropriate proportions. However, the air also contains other gases, vapours and aerosols that humans incorporate when breathing and whose composition and concentration vary spatially. Some of these are physiologically inert. Air pollution has become a problem of major concern in the last few decades as it has caused negative effects on human health, nature and properties. This book presents the results of research studies carried out by international researchers in seventeen chapters which can be grouped into two main sections: a) air quality monitoring and b) air quality assessment and management, and serves as a source of material for all those involved in the field, whether as a student, scientific researcher, industrialist, consultant, or government agency with responsibility in this area