Seasonal Variation of Nitrogen Oxides at Northern Midlatitudes

Seasonal Variation of Nitrogen Oxides at Northern Midlatitudes as Inferred from Ground- and Satellite-based Observations Lok Lamsal, Randall Martin, Aaron van Donkelaar Folkert Boersma, Ruud Dirksen (KNMI) Folkert Boersma, Ruud Edward Celarier, Eric. Dirksen Bucsela, (KNMI) James Edward Celarier, Eric Bucsela, James Gleason (NASA, GSFC) Gleason (NASA) E. S. Edgerton, B. Hertsell (ARA Inc. ) Y. Wang, C. Luo (Georgia Institute of Technology) MOCA-09, Montreal, July 19 -29 28. 07. 2009 07. 04. 2009

Substantial Seasonal Difference in Tropospheric NO 2 Columns: Example from GOME (71 -90 W, 35 -43 N) Uni Bremen BIRA/KNMI Dalhousie/SAO Retrievals from University of Bremen, Dalhousie/SAO, BIRA/KNMI Difference in winter up to a factor of 2 Monthly tropospheric NO 2 columns over Eastern U. S. from three independent retrievals van Noije, ACP, 2006

Large Seasonal Difference in Tropospheric NO 2 Columns Among OMI Retrievals Standard Product (SP) DOMINO Product (DP) Modified DP (DP_GC) DP_GC DOMINO product with stripes correction and GEOS-Chem NO 2 profiles Research Questions: How does the actual seasonal variation look like? Which one is closer to reality? What causes the observed difference? Monthly tropospheric NO 2 columns over the United States from OMI What drives the seasonal variation?

Comparison of OMI NO 2 with Surface Measurements (A) In-situ surface NO 2 measurements from the SEARCH and EPA/AQS networks (Rural sites only) � SEARCH (3) × EPA/AQS (8) (B) Derive surface-level NO 2 from OMI (Lamsal et al. , 2008, JGR) ,

Comparison of OMI-derived Emission with Bottom-up Inventory (A) Updated bottom-up emission inventories VISTAS 2002 and CAC 2005 (North America) EMEP 2005 (Europe) Street 2006 (East Asia) (B) Derive top-down emissions from OMI (Martin et al. , 2003, JGR)

Summary of Comparison - Validation of OMI Tropospheric NO 2 SEARCH, Southeastern U. S. SEARCH domain AQS/EPA, U. S. North America

What Causes the Observed Difference? Algorithm component Standard product (SP) DOMINO (DP) Slant column DOAS fit (405 -465 nm) Same as SP Stripe correction? Yes No Strat-trop separation Analysis of observation TM 4 assimilation Trop NO 2 profile GEOS-Chem annual Daily TM 4 DP_GC Yes Daily GEOSChem AMF Scattering weights TOMRAD DAK Surface reflectivity GOME climatology GOME+TOMS Surface pressure Climatological ECMWF Cloud pressure/fraction O 2 -O 2 cloud algorithm Same as SP

Difference Between DP and SP: Contribution of Stratosphere-troposphere Separation and AMF Strat-trop separation Air mass factor Combined

What Drives the Seasonal Variation in Tropospheric NO 2? Seasonal variation in (a) NOx emissions (b) NOx lifetime Gas phase (NO 2 + OH) Aerosol uptake of NO 2, NO 3, and N 2 O 5 OMI time τOMI Daily Average ττGC GC OMI time

Indirect validation of tropospheric nitrogen dioxide retrieved from the OMI satellite instrument: Insight into the seasonal variation of nitrogen oxides at northern midlatitudes, 2009, L. N. Lamsal, R. V. Martin, A. van Donkelaar, E. A. Celarier, F. K. Boersma, R. Dirksen, C. Luo, and Y. Wang, J. Geophys. Res. , Submitted