EMeRGe: Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global Scales
Final Report Abstract
Megacities and other major population centres (MPCs) worldwide are major sources of air pollution, both locally and downwind. The assessment of the impact of MPC pollution on tropospheric chemistry is challenging. The data and analysis of the EMeRGe (Effect of Megacities on the transport and transformation of pollutants on the Regional to Global scales) international project provide a contribution to the understanding of this issue. The overarching scientific objective of EMeRGe is the study of the transport and transformation of local and regional pollution originating in MPCs. Airborne measurements, taking advantage of the long range capabilities of the HALO aircraft, were a focus of the project. The synergistic use and consistent interpretation of observational data having different spatial and temporal resolution (e.g. from ground-based networks, airborne campaigns, and satellite measurements) supported by modelling within a EMeRGe “best effort” international cooperation, provides a unique opportunity to test the current understanding of MPC pollution outflows. In the EMeRGe project, two field experiments were planned to provide an adequate set of measurements in time and space to enable the comparison of the photochemical transformation during the transport of plumes emerging from MPCs for regions having different approaches to air quality legislation. These experiments were conducted in summer 2017 over Europe and in the inter-monsoon period over Asia in spring 2018. The intensive observational periods (IOPs) involved 180 flight hours of HALO airborne measurements of ozone and its precursors, volatile organic compounds, aerosol particles and related species as well as coordinated ground-based ancillary observations at different sites. Perfluorocarbon (PFC) tracer releases and model forecasts supported the flight planning, the identification of pollution plumes and the analysis of chemical transformations during transport. An inflight comparison of HALO with the collaborating UK-airborne platform FAAM took place in Europe to assure accuracy and comparability of the instrumentation on-board. In addition, the EMeRGe flights over the Philippines contributed to the characterisation and validation of the TCCON (Total Carbon Column Observing Network) station in Burgos. EMeRGe made measurements of near- and far-field emissions, to provide insight into the complex air masses having local and distant sources. The transport patterns of several European and Asian MPC outflows were successfully identified and measured. The chemical processing of the MPC emissions was inferred from airborne observations of primary and secondary pollutants both trace gases and aerosols. The aging of the plumes was assessed in a different way. For example, the ratios between species having different chemical lifetimes is one approach. Alternatively, HYSPLIT calculations were used to determine the age of air masses. An example of such studies identified the secondary formation of HCOOH, as the air mass aged. In other studies, the transformation of the composition of ageing aerosol during the transport of MPC plumes was also observed. Some of the salient results from EMeRGe are briefly described in this report and in more detail in the dedicated reports about DFG EMeRGe studies. These are also the subject of separate publications in the EMeRGe ACP/AMT inter-journal special issue.
Publications
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Overview: On the transport and transformation of pollutants in the outflow of major population centres – observational data from the EMeRGe European intensive operational period in summer 2017, Atmos. Chem. Phys. Discuss.
Andrés Hernández, M. D., Hilboll, A., Ziereis, H., Förster, E., Krüger, O. O., Kaiser, K., Schneider, J., Barnaba, F., Vrekoussis, M., Schmidt, J., Huntrieser, H., Blechschmidt, A.-M., George, M., Nenakhov, V., Klausner, T., Holanda, B. A., Wolf, J., Eirenschmalz, L., Krebsbach, M., Pöhlker, M. L., Hedegaard, A. B., Mei, L., Pfeilsticker, K., Liu, Y., Koppmann, R., Schlager, H., Bohn, B., Schumann, U., Richter, A., Schreiner, B., Sauer, D., Baumann, R., Mertens, M., Jöckel, P., Kilian, M., Stratmann, G., Pöhlker, C., Campanelli, M., Pandolfi, M., Sicard, M., Gomez-Amo, J. L., Pujadas, M., Bigge, K., Kluge, F., Schwarz, A., Daskalakis, N., Walter, D., Zahn, A., Pöschl, U., Bönisch, H., Borrmann, S., Platt, U., and Burrows, J. P.
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Airborne measurement of peroxy radicals using chemical amplification coupled with cavity ring-down spectroscopy: The PeRCEAS instrument, Atmos. Meas. Tech., 13, 2577–2600
George, M., Andrés Hernández, M. D., Nenakhov, V., Liu, Y., and Burrows, J. P.
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Measurement and model data comparisons for the HALO-FAAM formation flight during EMeRGe on 13 July 2017, DLR FB 2020-48
Schumann, U.
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Validation of XCO2 and XCH4 retrieved from a portable Fourier transform spectrometer with those from in situ profiles from aircraft-borne instruments, Atmos. Meas. Tech., 13, 5149–5163
Ohyama, H., Morino, I., Velazco, V. A., Klausner, T., Bagtasa, G., Kiel, M., Frey, M., Hori, A., Uchino, O., Matsunaga, T., Deutscher, N. M., DiGangi, J. P., Choi, Y., Diskin, G. S., Pusede, S. E., Fiehn, A., Roiger, A., Lichtenstern, M., Schlager, H., Wang, P. K., Chou, C. C.-K., Andrés- Hernández, M. D., and Burrows, J. P.
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Contribution of the gas-phase reaction between hydroxyl radical and sulfur dioxide to the sulfate aerosol over West Pacific
Chen, Y.-W., Chen, Y.-C., Chou, C. C.-K., Hung, H.-M., Chang, S.-Y., Eirenschmalz, L., Lichtenstern, M., Ziereis, H., Schlager, H., Stratmann, G., Kaiser, K., Schneider, J., Borrmann, S., Obersteiner, F., Förster, E., Zahn, A., Chen, W.-N., Lin, P.-H., Chang, S.-C., Andrés Hernández, M. D., Wang, P.-K., and Burrows, J. P.
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Implementation of HONO into the chemistryclimate model CHASER (V4.0): roles in tropospheric chemistry
Phuc T. M. Ha, Yugo Kanaya, Fumikazu Taketani, M.Dolores Andrés Hernández, Benjamin Schreiner, Klaus Pfeilsticker, Kengo Sudo
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Oxidation pathways and emission sources of atmospheric particulate nitrate in Seoul: based on δ15N and Δ 17O of PM2.5
Lim, S., Lee, M., Savarino, J., and Laj, P.
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Reduction in black carbon aerosol emissions and concentrations during the COVID-19 lockdown quantified by aircraft measurements over Europe
Krüger, Ovid Oktavian, Bruna A. Holanda, Sourangsu Chowdhury, Andrea Pozzer, David Walter, Christopher Pöhlker, Maria Dolores Andrés Hernández, John Phillip Burrows, Christiane Voigt, Jos Lelieveld, Johannes Quaas, Ulrich Pöschl, and Mira L. Pöhlker
