1. Xiaomeng Jin1, Arlene Fiore1, Lee Murray2, Luke Valin3
Image Credit: 
NASA's Goddard Space Flight Center
Evaluating a space-based indicator of surface ozone sensitivity to emissions of NOx vs. NMVOC and applications to decadal trends
Xiaomeng Jin1, Arlene Fiore1, Lee Murray2, Luke Valin3
1. Lamont-Doherty Earth Observatory of Columbia University
2. Dept. of Earth and Environmental Sciences, University of Rochester
3. U.S. EPA Office of Research and Development, Research Triangle Park

2. Observing surface O3-NOx-VOC sensitivity from space: HCHO/NO2 (FNR)?
NOx-Limited
NOx ⬆ O3 ⬆
VOC ⬆ O3 ✕
> 2
Control
Vertically
Integrated
OMI HCHO/NO2 (FNR)
Martin et al., (2004); Duncan et al., (2010)
NO2 column
HCHO Column
AURA Satellite
VOC
NOx
Surface O3 ?
NO2
HCHO
Sillman (1995) ?
VOC-Limited (NOx-Saturated)
VOC ⬆ O3 ⬆
NOx ⬆ O3 ⬇
< 1
Control ? ?

3. d[O3]/dENOx > d[O3]/dEvoc d[O3]/dENOx > d[O3]/dEvoc
Deriving regime threshold values from GEOS-Chem (v9-02) emission perturbation simulations
-20% ENOx
-20% ENOx
d[O3]/dE (s/cm)
d[O3]/dE (s/cm)
-20% EVOC
-20% EVOC
NOx-Saturated
d[O3]/dENOx<0
NOx-Saturated
d[O3]/dENOx<0
NOx-Lmited
d[O3]/dENOx > d[O3]/dEvoc
NOx-Lmited
d[O3]/dENOx > d[O3]/dEvoc
Surface HCHO/NO2
Column HCHO/NO2

4. GEOS-Chem reveals different column-to-surface relationships of HCHO and NO2
We apply the MODELED column-to-surface scaling factor to the more robust regime threshold values of surface HCHO/NO2.
The resulting regime threshold values of column HCHO/NO2 vary in space and time.
Jin et al., submitted

5. The same OMI observation, different answers
Spatial and temporal correlation between model and space-based HCHO/NO2 depends on NO2 product.
Mean difference depends on HCHO product.
vs.
Jin et al., submitted

6. Monthly OMI HCHO/NO2 over New York City
Increasing NOx sensitivity over the NE United States as emissions decline
May OMI HCHO/NO2
OMI observation detects the transition to NOx-limited regime has shifted one- month earlier from 2005 to over New York City.
Implies continued efficacy of ground-level ozone abatement via regional NOx emission control programs.
2005
2015
Monthly OMI HCHO/NO2 over New York City
Jin et al., submitted

7. Summary: OMI HCHO/NO2 can detect the evolution of O3-NOx-VOC sensitivity (but with uncertainty)
Seasonal and spatial variations in the column-to- surface relationship should be considered when diagnosing ozone production regimes from space.
OMI observation shows increasing NOx sensitivity over the U.S.A, Europe, Japan, Korea and megacities in China from 2005 to 2015.
Issues: Large uncertainty at daily scale. The spatial resolution of OMI is unable to reveal O3 photochemistry at urban cores.

8. Europe: Increasing NOx sensitivity over urban areas
June OMI HCHO/NO2 over Europe
O3 production is becoming more sensitive to NOx emissions over London, Paris, Moscow.
Larger uncertainties of satellite retrieval over Europe.
Column-based observation weakens the seasonal cycle of O3-NOx-VOC sensitivity.
2005
2015
Monthly OMI HCHO/NO2 over Paris
Jin et al., submitted

9. East Asia: Heterogeneous trend of O3-NOx-VOC sensitivity
May OMI HCHO/NO2 over East Asia
Spatial and temporal expansion of VOC-limited regime due to increasing NOx emissions, suggesting the importance of VOC emission control (Jin and Holloway, 2015)
Three exceptions in China: Beijing, Shanghai and Pearl River Delta.
Increasing NOx sensitivity in Tokyo and Seoul.
2005
2015
Monthly OMI HCHO/NO2 over Guangzhou
Jin et al., submitted

10. Seasonal variation of Column-to-surface scaling factor of HCHO/NO2

11. Vertical Profiles of NO2 and HCHO in GEOS-Chem

12. Ozone Isopleth