Relationship Between NOx Emissions and NO2 Columns

1
Analysis of Satellite Observations to Estimate
Production of Nitrogen Oxides from Lightning
Randall Martin Bastien Sauvage Ian Folkins
Chris Boone Peter Bernath
Jerry Ziemke
Chris Sioris
University of Saskatchewan
2
Global Lightning NOx Emissions Remain Poorly
Constrained(113 Tg N/yr)
10-year Mean Flash Rate from the OTD LIS
Satellite Instruments
Global rate 445 flash/sec Christian et al. 2003
DJF
30 400 moles NO per flash
JJA
Flashes km-2 min-1
3
Top-down Information from the SCIAMACHY, ACE,
OMI, and MLS Satellite Instruments
SCIAMACHY Aug 2002-present Nadir spatial
resolution 60x30 km2 Tropospheric NO2 Columns
(Martin et al., in press)
ACE-FTS Jan 2004-present Limb
Measurements in the Upper Troposphere High
Resolution FTS (33 species) HNO3 (Bernath et al.,
2005 Boone et al., 2005)
OMI MLS Aug 2004-present Both instruments
onboard Aura satellite OMI nadir UV-Vis, 24x13
km2 with daily global coverage MLS thermal
emission microwave limb sounder Tropospheric O3
(Ziemke et al., in press)
4
Current Estimate of Annual Global NOx Emissions
Lightning 6 Tg N yr-1
Other NOx sources (fossil fuel, biofuel, biomass
burning, soils) 39 Tg N yr-1
1010 molecules N cm-2 s-1
5
Tropospheric NO2 Columns Retrieved from SCIAMACHY
Nov - Apr
NO/NO2 ? ? w Altitude
May - Oct
Retrieval Uncertainty (5x1014 molec cm-2 30)
Tropospheric NO2 (1015 molecules cm-2)
Martin et al., in press
6
Simplified Chemistry of Nitrogen OxidesExploit
Longer Lifetimes in Upper Troposphere
Upper Troposphere
hv
NO
NO2
Ozone (O3)
O3, RO2
lifetime month
NOx lifetime week
HNO3
lifetime weeks
NO/NO2 ? ? with altitude
Boundary Layer
hv
NO2
Ozone (O3)
NO
O3, RO2
lifetime days
NOx lifetime lt day
HNO3
Nitrogen Oxides (NOx)
7
Strategy

• 1) Use chemical transport model to identify
  species, regions, and time periods dominated by
  the effects of lightning NOx emissions
• 2) Constrain lightning NOx emissions by
  interpreting satellite observations in those
  regions and time periods

GEOS-Chem Chemical Transport Model

• Assimilated Meteorology (NASA GMAO)
• 2ox2.5o horizontal resolution, 30 vertical layers
• O3-NOx-VOC chemistry
• Lightning 6 Tg N/yr, Price and Rind (1992),
  Pickering et al. (1998)
• Aerosols SO42--NO3--NH4-H2O, dust, sea-salt,
  carbonaceous

Bey et al., 1999 Fiore et al., 2002 Martin
et al., 2002, 2003 Park et al., 2003, 2004
41 tracers 90 species 300 reactions
8
Calculated Monthly Contribution of Lightning and
Soils to NO2 Column
GEOS-Chem Tropospheric NO2 Column
Column Fraction from Lightning (6 Tg N / yr)
Column Fraction from Soils (6 Tg N / yr)
Jan
Jan
Jul
Jul
Unitless
Unitless
1015 molec cm-2
9
Annual Mean Tropospheric NO2 at Locations
Months with gt50 of Column from Lightning and
lt25 from Soils
SCIAMACHY (Uses 30 of Tropical Observations)
Meridional Average
GEOS-Chem with Lightning (62 Tg N yr-1)
GEOS-Chem with Lightning (-18 bias, r0.75)
SCIAMACHY
GEOS-Chem without Lightning (-72 bias, r0.70)
GEOS-Chem without Lightning
NO2 Retrieval Error lt 5x1014 molec cm-2
Tropospheric NO2 (1014 molec cm-2)
10
ACE HNO3 over 200-300 hPa for Jan 2004 Feb 2006
HNO3 Mixing Ratio (pptv)
Data from Boone et al., 2005
11
GEOS-Chem Calculation of Contribution of
Lightning to HNO3
HNO3 With Lightning (62 Tg N yr-1)
Focus on 200-300 hPa
Fraction of HNO3 from Lightning
No Lightning
HNO3 from Lightning
Fraction from Lightning
Jan
Jul
?pptv
Unitless
12
Annual Mean HNO3 Over 200-300 hPa at Locations
Months with gt 60 of HNO3 from Lightning
ACE (Uses 70 of Tropical Measurements)
Smoothed Meridional Average
GEOS-Chem with Lightning (62 Tg N yr-1)
GEOS-Chem with Lightning (-1 bias, r0.74)
ACE
GEOS-Chem without Lightning (-79 bias, r0.15)
GEOS-Chem without Lightning
HNO3 Retrieval Error 35 pptv
HNO3 Mixing Ratio (pptv)
13
OMI/MLS Tropospheric Ozone Column
Jan
Jul
Dobson units
Data from Ziemke et al. (in press)
14
Calculated Monthly Contribution of Lightning to
O3 Column
O3 Column from Lightning
Column Fraction from Lightning
Jan
Jul
Unitless
?Dobson Units
15
Annual Mean Tropospheric O3 Columns at Locations
Months with gt 40 of Column from Lightning
OMI/MLS (Uses 25 of Tropical Measurements)
Meridional Average
GEOS-Chem with Lightning (62 Tg N yr-1)
GEOS-Chem with Lightning (4 bias, r0.70)
OMI/MLS
GEOS-Chem without Lightning
GEOS-Chem without Lightning (-42 bias, r0.70)
O3 Retrieval Error lt 5 Dobson Units
Tropospheric O3 (Dobson Units)
16
Conclusions

• Global lightning NOx emissions are likely between
  4 8 Tg N / yr
• 6 Tg N / yr is a best estimate
• Further refinement will require
• - improved satellite retrieval accuracy (i.e.
  NO2)
• - more observations (i.e. HNO3)
• - model development to better represent
  processes (i.e. soil NOx, vertical transport, ice
  uptake of HNO3)

Acknowledgements

• National Aeronautics and Space Administration
  (NASA)
• Natural Sciences and Engineering Research Council
  of Canada (NSERC)