analysis of satellite observations to estimate production of nitrogen oxides from lightning
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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. - PowerPoint PPT PresentationTRANSCRIPT
Analysis of Satellite Observations to Estimate Production of Nitrogen Oxides from Lightning
Randall MartinBastien Sauvage
Ian FolkinsChris Sioris
Chris Boone Peter Bernath
University of Saskatchewan
Jerry Ziemke
Global Lightning NOx Emissions Remain Poorly ConstrainedGlobal Lightning NOx Emissions Remain Poorly Constrained(1–13 Tg N/yr)(1–13 Tg N/yr)
Flashes km-2 min-1
DJF
JJA
10-year Mean Flash Rate from the OTD & LIS Satellite Instruments10-year Mean Flash Rate from the OTD & LIS Satellite Instruments
Global rate 44±5 flash/sec [Christian et al. 2003]
30 – 400 moles NO per flash
Top-down Information from the SCIAMACHY, ACE, Top-down Information from the SCIAMACHY, ACE, OMI, and MLS Satellite InstrumentsOMI, and MLS Satellite Instruments
SCIAMACHY Aug 2002-presentNadir spatial resolution 60x30 km2
Tropospheric NO2 Columns (Martin et al., in press)
ACE-FTS Jan 2004-present Limb Measurements in the Upper TroposphereHigh Resolution FTS (33 species)HNO3 (Bernath et al., 2005; Boone et al., 2005)
OMI & MLS Aug 2004-presentBoth instruments onboard Aura satelliteOMI nadir UV-Vis, 24x13 km2 with daily global coverageMLS thermal emission microwave limb sounder Tropospheric O3 (Ziemke et al., in press)
Current Estimate of Annual Global NOx EmissionsCurrent Estimate of Annual Global NOx Emissions
1010 molecules N cm-2 s-1
Lightning
6 Tg N yr-1
Other NOx sources: (fossil fuel, biofuel, biomass burning, soils)
39 Tg N yr-1
Tropospheric NOTropospheric NO22 Columns Retrieved from SCIAMACHY Columns Retrieved from SCIAMACHY
Retrieval Uncertainty
±(5x1014 molec cm-2 + 30%)
Martin et al., in pressTropospheric NO2 (1015 molecules cm-2)
Nov - Apr
May - Oct
NO/NO2
w Altitude
Simplified Chemistry of Nitrogen OxidesSimplified Chemistry of Nitrogen OxidesExploit Longer Lifetimes in Upper TroposphereExploit Longer Lifetimes in Upper Troposphere
NO NO2
NOx lifetime < day
Nitrogen Oxides (NOx)
BoundaryLayer
NO/NO2
with altitude
hv
NO NO2
O3, RO2
hv
HNO3
NOx lifetime ~ week
lifetime ~ weeks
Ozone (O3)lifetime ~ month
Upper Troposphere
Ozone (O3)
lifetime ~ days
HNO3
O3, RO2
StrategyStrategy
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 ModelGEOS-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., 2002Martin et al., 2002, 2003Park et al., 2003, 2004
41 tracers ~90 species 300 reactions
Calculated Monthly Contribution of Lightning and Soils to Calculated Monthly Contribution of Lightning and Soils to NONO22 Column Column
Column Fraction from Lightning (6 Tg N / yr)
Column Fraction from Soils (6 Tg N / yr)
UnitlessUnitless
Jan
Jul
Jan
Jul
GEOS-Chem Tropospheric NO2 Column
1015 molec cm-2
Annual Mean Tropospheric NOAnnual Mean Tropospheric NO22 at Locations & Months with at Locations & Months with
>50% of Column from Lightning and <25% from Soils>50% of Column from Lightning and <25% from Soils
Meridional Average
SCIAMACHY (Uses 30% of Tropical Observations)
GEOS-Chem with Lightning (-18% bias, r=0.75)
GEOS-Chem without Lightning (-72% bias, r=0.70)
Tropospheric NO2 (1014 molec cm-2)
NO2 Retrieval Error < 5x1014 molec cm-2
GEOS-Chem with Lightning (6±2 Tg N yr-1)
SCIAMACHY
GEOS-Chem without Lightning
ACE HNOACE HNO33 over 200-300 hPa for Jan 2004 – Feb 2006 over 200-300 hPa for Jan 2004 – Feb 2006
HNO3 Mixing Ratio (pptv)Data from Boone et al., 2005
GEOS-Chem Calculation of Contribution of Lightning to HNOGEOS-Chem Calculation of Contribution of Lightning to HNO33
HNO3 from Lightning Fraction from Lightning
Δpptv Unitless
Focus on 200-300 hPa
HNO3 With Lightning (6±2 Tg N yr-1)
No Lightning
Fraction of HNO3 from Lightning
Jan
Jul
Annual Mean HNOAnnual Mean HNO33 Over 200-300 hPa at Locations & Over 200-300 hPa at Locations &
Months with > 60% of HNOMonths with > 60% of HNO33 from Lightning from Lightning
Smoothed Meridional AverageACE (Uses 70% of Tropical Measurements)
GEOS-Chem with Lightning (-1% bias, r=0.74)
GEOS-Chem without Lightning (-79% bias, r=0.15)
HNO3 Mixing Ratio (pptv)
ACE
GEOS-Chem with Lightning (6±2 Tg N yr-1)
GEOS-Chem without Lightning
HNO3 Retrieval Error ~35 pptv
OMI/MLS Tropospheric Ozone ColumnOMI/MLS Tropospheric Ozone Column
Jan
Jul
Dobson units Data from Ziemke et al. (in press)
Calculated Monthly Contribution of Lightning to OCalculated Monthly Contribution of Lightning to O33 Column Column
O3 Column from Lightning
Column Fraction from Lightning
ΔDobson Units Unitless
Jan
Jul
Annual Mean Tropospheric OAnnual Mean Tropospheric O33 Columns at Locations & Columns at Locations &
Months with > 40% of Column from LightningMonths with > 40% of Column from Lightning
Meridional AverageOMI/MLS (Uses 25% of Tropical Measurements)
GEOS-Chem with Lightning (4% bias, r=0.70)
GEOS-Chem without Lightning (-42% bias, r=0.70)
Tropospheric O3 (Dobson Units)
OMI/MLS
GEOS-Chem with Lightning (6±2 Tg N yr-1)
GEOS-Chem without Lightning
O3 Retrieval Error < 5 Dobson Units
ConclusionsConclusions
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)
AcknowledgementsAcknowledgements
• National Aeronautics and Space Administration (NASA)
• Natural Sciences and Engineering Research Council of Canada (NSERC)