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

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

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

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

 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 ] Lightning Properties Observed from Space [Beirle et al., 2014]

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

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)

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

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

Bonus Slides

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

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

 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

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 Vertical Distribution

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