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Xiaomeng Jin and Arlene Fiore
Photochemical Modeling Coordination Call Analyzing surface O3 sensitivity to NOx and VOC emissions: the view from space Xiaomeng Jin and Arlene Fiore Department of Earth and Environmental Sciences Lamont-Doherty Earth Observatory Columbia University in the City of New York
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Space-based ozone-NOx-VOC sensitivity indicator: HCHO/NO2 (FNR)
Satellite observation of FNR (Martin et al., 2004; Duncan et al., 2010): FNR < 1: VOC-Limited FNR > 2: NOx-limited 1 < FNR < 2: transitional Aura’s satellite’s Ozone Monitoring Instrument (OMI) Daily global coverage Two products: TEMIS (Netherland) and NASA Level-2 data resolution: 13 km × 14 km (interpolated to model grid). Level-3 data: 0.25 ° × 0.25 °, Global Chemical Transport Model (GEOS-Chem v 9.02) Driven by MERRA meteorology at 2 × 2.5 °, 47 vertical layers,
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Data source: NASA Level-3 NO2 and TEMIS Level-3 HCHO
NOx-limited regime is dominated over the eastern U.S. in warm season (May to September) 2005 (warm season) 2015 (warm season) Data source: NASA Level-3 NO2 and TEMIS Level-3 HCHO
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HCHO/NO2 over the eastern U.S. averaged for non-attainment days
2005 (MDA8 >70 ppbv) 2012 (MDA8 >70 ppbv) 2013 (MDA8 >70 ppbv) OMI NASA Level-3 NO2 and TEMIS Level-3 HCHO Observed Ozone MDA8 data: from Jordan L. Schnell; 1x1 gridded product (spatial and temporal interpolation of U.S. AQS, CASTNet, Canadian NAPS [Schnell et al., ACP, 2014; 2015]
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Increasing NOx sensitivity in NYC
HCHO/NO2 ≦ 1.0: VOC-limited HCHO/NO2 ≧ 2.0: NOx-limited 1.0 < HCHO/NO2 < 2.0: Transitional
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Is HCHO/NO2 useful for guiding emission control strategies?
GC Surface HCHO/NO2 GC Column HCHO/NO2 OMI observed HCHO/NO2 Model: GEOS-Chem V9.02 Delta Ozone = Surface ozone (20% NOx emission reduction) - surface ozone (base) Time period: OMI overpass time (1:30 PM Local time) from 2005 to 2012
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Summary Space-based tropospheric column ratios of formaldehyde to NO2 indicate that NOx emission reductions are the most effective way to control surface ozone. Eastern US cities are becoming more NOx-sensitive (as expected due to NOx emission controls). Space-based view provides insights, though uncertainties exist: noisy satellite retrievals at the daily scale; column (viewed from space) may not always represent near-surface air; the transition value may vary.
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Thank you! Questions? Acknowledgements: Lee Murray (CU/LDEO)
Luke Valin (EPA) Tracey Holloway (UW-Madison) Bryan Duncan (NASA GSFC)
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