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Ozone source attribution from intercontinental to regional scales. Tim Butler, Aurelia Lupascu, Aditya Nalam (Terry Keating, Frank Dentener and all of the HTAP2 modellers ). Institute for Advanced Sustainability Studies, Potsdam ( tim.butler@iass-potsdam.de ) TFMM, Madrid, 8 .5.2019.
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Ozone source attribution from intercontinental to regional scales Tim Butler, Aurelia Lupascu, Aditya Nalam (Terry Keating, Frank Dentener and all of the HTAP2 modellers) Institute for Advanced Sustainability Studies, Potsdam (tim.butler@iass-potsdam.de) TFMM, Madrid, 8.5.2019
Outline • Short summary of HTAP2 results • “Response to Extra-Regional Emissions Reductions” • Importance of methane as an ozone precursor • Quick reality check: comparison with TOAR observations • An alternative source attribution approach: “tagging” • Long-range contribution to European surface ozone • The regional scale: Iberian Peninsula • The urban scale: Berlin • HTAP future directions
HTAP Resources • https://www.atmos-chem-phys.net/special_issue390.html • 48 papers • Summary report in preparation • http://www.htap.org/
HTAP2 experiments • ~15 global models • Harmonised anthropogenic emissions for 2008-2010 • 20% emission perturbation in source regions • Response in receptor regions
Response to Extra-Regional Emission Reductionsof European PM and ozone (annual mean) RERER=0: regional sensitivity RERER=1: extra-regional sensitivity = Source: draft HTAP2 report
Ozone response to 20% increased methane TM5 Model Van Dingenen et al. (2018)
Surface ozone: TOAR and the HTAP2 ensemble NW US NE US NW Europe Korea SW US SE US SW Europe Japan
Tagging tropospheric ozone Stratosphere-troposphere exchange NOx tagging O3_X_STR VOC tagging NO + RO2→ NO2 (+ R’) → O3 NO_TAG + RO2→ NO2 (+ R’) → O3_X_TAG NO + RO2_TAG→ NO2 (+ R’) → O3_X_TAG NOx precursors VOC precursors
20% increase in methane: response of NOx precursors Change in ozone (ppb)
Spain and Portugal Long-range contribution to ozone metrics in Spain/Portugal Sources inside Europe Natural sources Inter- continental transport Cumulative impact metrics April - June July – Sept.
Summary and outlook • Hemispheric transport is more important for ozone than PM • Background ozone is very sensitive to methane concentration • Synergistic effects between methane and international shipping • Nearby sources are more important for high ozone conc. (and impact metrics) • But hemispheric transport still contributes ca. 20-30% to regional-scale impacts • Springtime ozone especially influenced by hemispheric transport of ozone from anthropogenic precursors • Ozone tagging should be implemented in more models before being considered a robust source attribution technique
NOx tagging schematic NO2_X_TAG O3_X_TAG + RO2 + O3 NO_TAG NO2_TAG
VOC tagging schematic O3_X_TAG NO2 NO2_X_TAG OH VOC_TAG RO2_TAG VOC’_TAG NO
Annual average surface ozone: NOx-tagged Parts per billion
Annual average surface ozone: VOC-tagged Parts per billion
Ozone production efficiency of NOx precursors Moles of ozone per mole of NOx emitted
Ozone production efficiency of VOC precursors Moles of ozone per mole of C emitted