Relationship Between NOx Emissions and NO2 Columns

1
Satellite and Aircraft Based Constraints on NOX
Emissions
Chris Sioris Kelly Chance
Randall Martin
Tom Ryerson Andy Neuman
CIRES
Ron Cohen
Aaron Swanson Frank Flocke
UC Berkeley
NCAR
2
Air Mass Factor Calculation in SCIAMACHY
Retrieval Needs External Info on Shape of
Vertical Profile
RADIATIVE TRANSFER MODEL
ATMOSPHERIC CHEMISTRY MODEL
Shape factor
sigma (?)
NO2 mixing ratio CNO2(?) norm. by column ONO2
Scattering weight
Individual SCIAMACHY Scenes
?(?) is temperature dependent cross-section

• Calculate w(?) as function of
• solar and viewing zenith angle
• surface albedo, pressure
• cloud pressure, frac
• aerosol profile, type

3
Increased NOx Emissions from Midlatitude Improves
GEOS-CHEM Simulation of NO2 Profiles Used in
Retrieval Remaining Discrepancy In Vertical
Profile of NOx Emissions (i.e. importance of
cloud-cloud flashes)
In Situ 0.4 Tg N yr-1 1.6 Tg N yr-1
Midlatitude lightning Mean Bias in AMF 0.4
Tg N yr-1 12 9 3 1.6 Tg N
yr-1 1 5 3
4
Enhanced Midlatitude Lightning Reduces
Discrepancy with SCIAMACHY over North Atlantic
Profile of NOx Emissions (lifetime) May Explain
Remaining Discrepancy
SCIAMACHY NO2 (1015 molec cm-2)
GEOS-Chem NO2 (1015 molec cm-2) 1.6 Tg N in Midlat
GEOS-Chem NO2 (1015 molec cm-2) 0.4 Tg N in Midlat
May-Oct 2004
5
Significant Agreement Between Coincident
Cloud-Filtered SCIAMACHY and In-Situ Measurements
r 0.79 slope 0.8
11 line

• Coincident measurements
• Cloud-radiance fraction lt 0.5
• In-situ measurements below 1 km above 3 km
• Assume constant mixing ratio below lowest
  measurement
• Add upper tropospheric profile from mean obs

Cohen NO2
Ryerson NO2
Horizontal bars show 17th 83rd percentiles
Chris Sioris
6
Cloud-filtered Tropospheric NO2 Columns Retrieved
from SCIAMACHY
May-Oct 2004
detection limit
7
Conduct a Chemical Inversion Combine Top-Down
and Bottom-up Inventories with Error Weighting
A Priori NOx Emissions
SCIAMACHY NO2 Columns
1011 molec N cm-2 s-1
1015 molec cm-2
GEOS-CHEM model
Error weighting
A posteriori emissions
Top-Down Emissions
8
Global Optimal Emission Inventory RevealsMajor
Discrepancy in NOx Emissions from Megacities
May-Oct 2004
r20.83 vs a priori
9
A Posteriori NOx Emissions from East Asia Exceed
Those from Either North America or Europe
10
Large Change in NOx Emissions Near New York City
A posteriori A priori
r2 0.92
A priori
A posteriori
7.8 Tg N
7.2 Tg N
0.6 Tg N
1011 atoms N cm-2 s-1
1011 atoms N cm-2 s-1
?1011 atoms N cm-2 s-1
Evaluate Each Inventory By Conducting GEOS-CHEM
Simulation Sampling Model Along Aircraft Flight
Tracks
Simulation with A Posteriori Simulation with A
Priori
?NOx (pptv)
?PAN (pptv)
?HNO3 (pptv)
11
In Situ Airborne Measurements Support A
Posteriori Inventory
New England
New England
New England Gulf
GEOS-CHEM (A priori)
GEOS-CHEM (A posteriori)
In Situ
P-3 Measurements from Tom Ryerson (NOAA)
Aaron Swanson Andy Neuman
Frank Flocke (NCAR) (CIRES/NOAA)
Horizontal bars show 17th 83rd percentiles
12
Conclusions

• Growing confidence in top-down constraint on NOx
  emissions
• Underestimate in NOx emissions from megacities
• North American lightning NOx emissions
  underestimated