1. Assessing the Lightning NO x Parameterization in GEOS-Chem with HNO 3 Columns from IASI Matthew Cooper 1 Randall Martin 1,2, Catherine Wespes 3, Pierre-Francois Coheur 3, Cathy Clerbaux 3,4, Lee Murray 5 1. Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada. 2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA 3. Spectroscopie de l’Atmosphère, Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, Belgium 4. Sorbonne Universités, UPMC Univ. Paris 06; Université Versailles St-Quentin; CNRS/INSU, LATMOS-IPSL, Paris, France 5. NASA Goddard Institute for Space Studies and Lamont-Doherty Earth Observatory of Columbia University, NY, USA

2. 20-24 Tg 3-13 Tg 4-15 Tg 4-8 Tg HNO 3 Observations Can Be Used To Constrain NO x Emission Inventories

3. GEOS-Chem HNO 3 Biased Low Over SE Asia IASI Annual Mean Tropospheric HNO 3 Column molec/cm 2 IASI – GEOS-Chem Percent Difference molec/cm 2 Percent GEOS-Chem Annual Mean Tropospheric HNO 3 Column

4. CO Observations Can Identify Transport Of Combustion Sources  Anthropogenic, Biomass burning sources emits NO x, CO  Long lifetime of CO allows for evaluation of transport  Lightning NO x source is independent CO

5.  GEOS-Chem has 4 lightning regimes: Land – Ocean – Tropics – Midlatitudes  SE Asia lightning properties are different, which may lead to biases Simulated IC/CG Flash Ratio Regional Variations In Lightning Properties Not Captured By GEOS-Chem Simulated IC/GC Flash Ratio Flash Footprint [km 2 ] 600 400 200 0 Lightning Properties Observed from Space [Beirle et al., 2014]

6. The GEOS-Chem Lightning NO X Parameterization Prescribed NO x /flash (260 mol/flash) Flash rates match satellite observations Prescribed vertical profiles Emissions added to GEOS-Chem 4°x5° grid boxes

7. LNO x Plumes have Sub-Grid Spatial Scale. NO x Chemistry is Non-linear.  Early subgrid plume has high NO x concentration  Leads to rapid HNO 3 production, lower OPE  This is not represented in the model Actual Plume PHNO 3 (molec cm -3 s -1 ) / OPE (mol/mol) 4°x5° GC grid box NO x concentration (ppbv)

8. A Simple LNO x Plume Pre-processor GC Grid Box NO x HNO 3 + 15O 3 Current MechanismWith Pre-Processing Adding 0.5 Tg N to Southeast Asia gives better agreement GC Grid Box NO x -1.0 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 HNO 3 Tropospheric Column (IASI – Standard GEOS-Chem)/IASI (IASI – GC w/ PreProcessor)/IASI 92% Bias 6% Bias

9. Conclusions  GEOS-Chem underestimates HNO 3 in Southeast Asia  Lightning NO x is most likely contributor to bias  A preprocessor representing early stages of lightning plume improves the simulation

10. Bonus Slides

11. Inferring Tropospheric Contribution to Total Column  Apply IASI averaging kernel to GC output = “total column”  Set GC troposphere to zero then apply kernel = “strat column”  Infer tropospheric column = “total” – “strat” Sensitivity GC Total HNO 3 Column Total Column Smoothed w/ IASI Kernel GC Tropospheric HNO 3 Column Altitude (hPa) IASI Vertical Sensitivity Tropospheric Column Smoothed w/ IASI Kernel

12. Convective Effects Scaled Mass Flux by 25%Scaled scavenging efficiency by 50%  Southeast Asia/ West Pacific is highly convective region  HNO 3 highly soluable – easily washed out  Can have an impact, but its small  20% change vs 200% bias

13.  GEOS-Chem lightning scaled by observed flash density  SE Asia lightning flashes are longer, more radiant than elsewhere in tropics  Intra-cloud lightning more common in SE Asia [Beirle et al., Nat. Hazards Earth. System. Sci. Discuss, 2014] Simulated IC/CG Flash Ratio Some Regionally Varying Lightning Properties that could Affect SE Asia Lightning Properties Observed by OTD/LIS Simulated IC/GC Flash Ratio

14. Vertical Distribution of NO x Emissions  NO x lifetime increases with altitude  Not much change in column near emissions region  Change (~30%) is small compared to the bias vs IASI (~200%) Tropospheric HNO 3 Column Ratio: Adjusted/Standard 1.3 1.2 1.1 1.9.8.7 Vertical Distribution

15. LNO x Plume Pre-processor VS Prescribed Flash Yield Adding 0.5 Tg N to Southeast Asia gives better agreement Ozonesonde Standard 3.5x Nox Pre-Process HNO 3 Tropospheric Column (IASI – Standard GEOS-Chem)/IASI (IASI –GEOS-Chem w/ Pre-Processor)/IASI