1. Satellite Remote Sensing of Ground-Level NO2 for New Brunswick
Randall Martin and Lok Lamsal
Dalhousie University

2. Major Nadir-viewing Space-based Measurements of AQHI Species
Solar Backscatter & Thermal Infrared
Sensor
MISR
MODIS
SCIA-MACHY
TES
OMI
PARA-SOL
GOME-2
IASI
S-5 Precursor
Platform (launch)
Terra Aqua
(1999) (2002)
Envisat (2002)
Aura
(2004)
PARA-SOL (2004)
MetOp
(2006, 2011, 2016)
2014?
Equator Crossing
10: :30
10:00
1:45
1:30
9:30
Typical Res (km)
18x18
10x10
60x30
8x5
>24x13
18x16
80x40
12x12
7x7
Global Obs
(w/o clouds) 7 2 6
n/a 1
0.5
Aerosol X
NO2
Ozone
AQHI ~ 0.09*NO2 (ppbv) *PM2.5 (ug/m3) *O3(ppbv)
Proposed: MCAP (CSA), GEO-CAPE (NASA)

3. Use Satellite Observations to Improve Emissions Inventories, and In Turn Simulations

4. Tropospheric NO2 Column Proxy for Surface Concentration
NO/NO2  
with altitude
Satellite more representative for Exposure
OMI Tropospheric NO2 Column (1015 molecules cm-2) for 2005
Daily Retrieval Uncertainty: 1x1015 molec cm % of trop column
Data from Lamsal et al., JGR, in press

5. General Approach to Estimate Surface Concentration
Coincident Model Profile
Daily Observed Column
In Situ
GEOS-Chem
S → Surface Concentration
Ω → Tropospheric column

6. Significant Correlation Between In Situ and OMI-derived Surface NO2; Less Clear for New Brunswick
DOMINO
Correlation with Coincident “Corrected” Observations over 2005
Lamsal et al., JGR, 2008

7. New Brunswick Generally Has Low NO2 Concentrations
Annual mean in early afternoon ~13:45 for 2005
OMI-derived Surface NO2 Concentration (ppbv)

8. ... However There are Transient Events
Early Afternoon (13:00 – 14:00) NO2 Concentration
Mean OMI-derived NO2 for New Brunswick

9. More Analysis Needed for Direct Comparison
Collocated measurements (OMI Black x 5)
Different spatial scales
No NOz interference correction
Local sources?

10. Interference in Molybdenum Converter Measurements in Southeast US (YRK)
Photolytic / Molybdenum
Modeled (GEOS-Chem)
~NO2 / 0.1*ΔO3 [14:00 – 10:00] (Boersma et al., ACP, 2009)
Lamsal et al., JGR, in press

11. OMI Observes During Minimum NO2 Observations from EPA air quality network
mean
median
Lamsal et al., JGR, 2008

12. Possible Strategy Issues
Use satellite to monitor for extreme events (i.e. when partial AQHI from NO2 exceeds a threshold)
Issues
Examine wintertime spikes; caution over snow
Interference in ground-based NO2 measurements
Assess diurnal variation with in situ
Cloud-free: test clear sky bias
“Row Anomaly” restricts OMI Coverage; may need to consider GOME-2