Why study ship NOx emissions?

Vinken et al., in prep., 2012

• 15-30% of global NOx 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

Detecting emission patterns with OMI

OMI shows that EMEP emissions are misplaced

(2.5 Tg NO2)

(3.7 Tg NO2)

Use GEOS-Chem a priori NO2 profiles in OMI NO2 retrieval

• OMI (DOMINO v2) retrieval uses TM4 a priori (3°x2°) NO2 vertical profiles

• Replace these 3°x2° profiles with high resolution GEOS-Chem NO2 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

SstSAMF

Comparison OMI & GEOS-Chem over Europe for 2005-2006

DOMINO_GC columns are 10-15% lower than DOMINO v2(mainly due to changed

emissions in model)

R2 = 0.95 for DOMINO_GC and GEOS-Chem

Closer agreement between model and observations

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!

Track 4 (Med. Sea) for 2005

Vinken et al., in prep., 2013

Track 4 (Med. Sea) for 2005

Vinken et al., in prep., 2013

Emissions decreased by 57%

before

New constrained inventory for 2005

AMVER-ICOADS (2.5 Tg NO2) EMEP (3.7 Tg NO2)

Constrained ship tracks OMI top down inventory (3.3 Tg NO2)

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 Seathan EMEP

• OMI total is 3.3 Tg NO2 (10% lower than EMEP)

Backup slides

Selection of best OMI observations

• Screen out measurements affected by outflow2005 filtered meanOMI trop. NO2 27-10-2005

OMI trop. NO2 9-7-2005

Sensitivities when constraining emissions

• Account for sensitivity GEOS-Chem NO2 columns (ΩGC) to NOx emissions (E)

β = ΔE / E e ΔΩGC / ΩGC

• Account for sensitivity OMI NO2 columns (ΩOMI) to changing GEOS-Chem a priori profiles (higher emissions -> GC columns -> lower AMFs -> higher OMI columns)

γ = ΔΩOMI / ΩOMI e ΔΩGC / ΩGC

Vinken et al., in prep., 2013

[Lamsal et al., GRL, 2011]