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 Meeting2-5 May, 2011

Problem Lightning-NOx has 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)

Flash rate Fraction at altitude z

Before: “C-shape” (2D-cloud model) Now: “backward C-shape” (3D-cloud model) LiNOx remain in mid/upper troposphere

(Courtesy Lee Murray)

Tropical land profile hypothetical (not from 3D-cloud simulation)

Assuming a gaussian profile shape, consider :Methodology

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ELiNOx(z) = FR.σ NOyield . NOyield. e−

12

z−σ injhinjh

s

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⎝ ⎜

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⎠ ⎟2

Optimizing NOyield/flash and injection height:

Constraint: TES O3 Nadir profiles (V003), winter 2006

Problem: need to uncouple impacts of NOyield/flash and injection height on O3

Metric for injection height:

(σNOyield, injh scaling factors)

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)

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rO3 =O3(195hPa)O3(562hPa)

Need to check using sensitivity tests

GEOS-Chem sensitivity tests

Biomass burning (+30%)

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injhsensNOyieldsens

>10,injhsensbbsens

>10 O3 ratio most sensitive to injection height

O3(195hPa)/O3(562hPa) O3(195hPa)/O3(562hPa)

TESGEOS-Chem w/ AKs

NOyield/flash (+20%)Injection height (7 10 km)

Δ ( O3(195hPa)/O3(562hPa ) )

Δ ( O3(195hPa)/O3(562hPa ) )

Δ ( O3(195hPa)/O3(562hPa ) )

O3(195hPa)/O3(562hPa) sensitivity to:

4D-Var inversion using the adjoint of GEOS-Chem

Best Linear Unbiased Estimator is the minimum of:

• σinjh scaling factor, H TES observational operator, Sobs, σ error covariance matrices, Ω domain 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%€

∇σ injhJ

Pseudo-observations inversion tests

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

σ σ

2 weeks-assimilation of pseudo-observations

1.00 1.2 1.40

0.60 0.80 1.00

Preliminary results2 weeks-assimilation of TES O3 observations (12/01/0612/15/06) (GEOS-4)

0 4 8 12 0 4 8 12[km] [km]

-13% -23% -7%

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

Original OptimizedGC injection height

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