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Constraining the lightning- NO x ( LiNOx ) source using TES O 3 observations

Constraining the lightning- NO x ( LiNOx ) source using TES O 3 observations. N. Bousserez , R.V. Martin, K.W. Bowman, D.K. Henze. 5th International GEOS– Chem Meeting 2-5 May, 2011. Problem.

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Constraining the lightning- NO x ( LiNOx ) source using TES O 3 observations

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  1. Constraining the lightning-NOx (LiNOx) source using TES O3 observations N. Bousserez, R.V. Martin, K.W. Bowman, D.K. Henze 5th International GEOS–Chem Meeting 2-5 May, 2011

  2. Problem • Lightning-NOxhas large impact on tropical tropospheric O3(> 28% of the annual O3 burden) • Large uncertainties in CTM: • Cloud-Top-Height (CTH) parameterization (Price and Rind, 1992): • Profile shapes used: ELiNOx(z) = 3.44x10-5 CTH4.90 NO yield/flash frac(z) Fraction at altitude z Flash rate • Before: “C-shape” • (2D-cloud model) • Now: “backward C-shape” • (3D-cloud model) • LiNOx remain in mid/upper troposphere Tropical land profile hypothetical (not from 3D-cloud simulation) (Courtesy Lee Murray)

  3. GC adjoint v8-02-01 • Sensitivities w.r.t. NOyield/flash, injection height: • Minimize the cost function: • Invert σNOyieldand σinjh simultaneously, globally, what time window? • Non-linearity leads to multiple minima Methodology Assuming a gaussian profile shape, consider : • Optimizing NOyield/flash and injection height: • Constraint: TES O3Nadir profiles (V003), winter 2006 • Problem: need to uncouple impacts of NOyield/flash and injection height on O3 • Metric for injection height: (σNOyield, injhscaling factors) 4D-var analysis If we assume a linear relationship between O3 production and LiNOx emissions, rO3 is: • Sensitive to change in injection height • Not sensitive to change in NO yield/flash(scaling) Need to check using sensitivity tests If we assume a linear relationship between O3 production and LiNOx emissions, the ratio is: • Sensitive to injection height • Not sensitive to NO yield/flash

  4. GEOS-Chem sensitivity tests GEOS-Chemw/ AKs TES O3(195hPa)/O3(562hPa) O3(195hPa)/O3(562hPa) O3(195hPa)/O3(562hPa) sensitivity to: NOyield/flash (+20%) Biomass burning (+30%) Injection height (7  10 km) Δ ( O3(195hPa)/O3(562hPa ) ) Δ ( O3(195hPa)/O3(562hPa ) ) Δ ( O3(195hPa)/O3(562hPa ) ) O3 ratio most sensitive to injection height

  5. 4D-Var inversion using the adjointof GEOS-Chem Best Linear Unbiased Estimator is the minimum of: • σinjhscaling factor, H TES observational operator, Sobs, σerror covariance matrices, Ωdomain of observations (distributed in space and time) • Iterative solution need for adjoint of GEOS-Chem (v8-02-01) • Minimization over 3 tropical continental areas: Africa, Indonesia, South America • A priori error for injection height set to 30%

  6. Pseudo-observations inversion tests 2 weeks-assimilation of pseudo-observations • Generate pseudo-observations from GC simulations with perturbed injection heights: • A priori injection height x 1.2 • A priori injection height x 0.8 • Starting from the a priori (σ = 1) we assimilate the pseudo-observations • The inversion allows to recover reasonably well the perturbed injection heights A priori injection height *1.2 A priori injection height *0.8 0.60 0.80 1.00 1.00 1.2 1.40 σ σ

  7. Preliminary results 2 weeks-assimilation of TES O3 observations (12/01/0612/15/06) (GEOS-4) GC injection height Original Optimized -23% -7% -13% [km] [km] 0 4 8 12 0 4 8 12 Alt Alt • Optimized injection heights lower than a priori • Tropical continental profile shape ~ mid-latitude continental? • Remark: we implicitly correct for bias in Cloud-Top-Height • bias in Cloud-Top-Height => bias in optimized profile shape • Next steps: • NOyield/flash inversion using optimized injection height • Evaluate the new LiNOx profiles using SHADOZ/MOZAIC in situ ozone profiles

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