1. Why study ship NO x emissions? Vinken et al., in prep., 2012 15-30% of global NO x emissions 70% of emissions within 400 km of densely populated coast lines Seaborne trade +5% per year Emission inventories Lots of estimations -> High uncertainty Often miss recent increases of emissions Improve inventories using combination of satellite observations and chemistry transport models

2. Detecting emission patterns with OMI OMI shows that EMEP emissions are misplaced (2.5 Tg NO 2 ) (3.7 Tg NO 2 )

3. Use GEOS-Chem a priori NO 2 profiles in OMI NO 2 retrieval OMI (DOMINO v2) retrieval uses TM4 a priori (3°x2°) NO 2 vertical profiles Replace these 3°x2° profiles with high resolution GEOS-Chem NO 2 profiles (0.667°x0.5°) to do consistent comparison Satellite observations never fully independent of model information, now we made sure the model information is consistent S st S AMF

4. Comparison OMI & GEOS-Chem over Europe for 2005-2006 Tropospheric NO 2 column (10 15 molec / cm 2 ) DOMINO_GC columns are 10-15% lower than DOMINO v2 (mainly due to changed emissions in model) R 2 = 0.95 for DOMINO_GC and GEOS-Chem Closer agreement between model and observations

5. Vinken et al., in prep., 2013 Comparing OMI and GEOS-Chem to get constraint on ship emissions Satellite Model 3 4 0.5°x0.667° resolution nested-grid GEOS-Chem using plume-in-grid approach for ship emissions 1 2 3 4 1 2 Reduce influence of outflow by filtering, making it possible to observe ship tracks in 4 seas!

6. Track 4 (Med. Sea) for 2005 Vinken et al., in prep., 2013 Tropospheric NO 2 column (10 15 molec / cm 2 )

7. Track 4 (Med. Sea) for 2005 Vinken et al., in prep., 2013 Tropospheric NO 2 column (10 15 molec / cm 2 ) Emissions decreased by 57% before

8. New constrained inventory for 2005 AMVER-ICOADS (2.5 Tg NO 2 )EMEP (3.7 Tg NO 2 ) Constrained ship tracks OMI top down inventory (3.3 Tg NO 2 )

9. Conclusions OMI shows that EMEP emissions are misplaced in Mediterranean Sea First-ever constraints on highly localized pollution of ships in Baltic Sea, North-Sea, and Bay of Biscay OMI constrained emissions are  -35% for North Sea  +140% for Baltic Sea  +130% Bay of Biscay  -57% in Mediterranean Sea than EMEP OMI total is 3.3 Tg NO 2 (10% lower than EMEP)

10. Backup slides

11. Selection of best OMI observations Screen out measurements affected by outflow 2005 filtered mean OMI trop. NO 2 27-10-2005 OMI trop. NO 2 9-7-2005

12. Sensitivities when constraining emissions Account for sensitivity GEOS-Chem NO 2 columns (Ω GC ) to NO x emissions (E) β = ΔE / E e ΔΩ GC / Ω GC Account for sensitivity OMI NO 2 columns (Ω OMI ) to changing GEOS-Chem a priori profiles (higher emissions -> GC columns -> lower AMFs -> higher OMI columns) γ = ΔΩ OMI / Ω OMI e ΔΩ GC / Ω GC Vinken et al., in prep., 2013 [Lamsal et al., GRL, 2011]