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Lightning NOx Source Emissions in GEOS-Chem. Lee T. Murray April 12, 2007 3rd GEOS-Chem Users’ Meeting Thanks to: Rynda Hudman, Bob Yantosca, Daniel Jacob, Jennifer Logan, Eric Leibensperger, Folkert Boersma, and others. NOx O 3. Current Annual NO x Source. Tg N/yr. Fossil Fuel Burning.

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Lightning nox source emissions in geos chem

Lightning NOxSource Emissions in GEOS-Chem

Lee T. Murray

April 12, 2007

3rd GEOS-Chem Users’ Meeting

Thanks to: Rynda Hudman, Bob Yantosca, Daniel Jacob, Jennifer Logan, Eric Leibensperger, Folkert Boersma, and others


Lightning an important source of no x

NOx O3

Current Annual NOx Source

Tg N/yr

Fossil Fuel Burning

28-32 (28)

Biomass Burning

4-24 (10)

Model

Obs

Lightning

1-20 (5-7)

Soil Emissions

1-16 (5.5)

Aviation

0.7-1 (0.7)

N2O Degradation

0.1-1 (0.4)

Total

~50

0.0 0.2 0.4 0.6

0 20 40 60 80 100

ppbv

ppbv

[Hudman et al 2007a]

[Schumann and Huntrieser 2007]

Lightning:An Important Source of NOx

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Global lightning distribution
Global Lightning Distribution

Optical Transient Detector (May 1995 -- Mar 2000)

Lightning Imaging Sensor (Dec 1997 -- present)

Combined HR Monthly Climatology

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group

flashes / sec / box


Original scheme pre v7 02 04
Original Scheme(pre-v7.02.04)

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Lnox parameterization

6 Tg N / yr

[Martin et al 2002]

[Pickering 1998]

[Price and Rind 1992]

LNOx Parameterization

Scaled to CTH

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Flashrate parameterization
Flashrate Parameterization

CTH

Flashrate parameterization of Price and Rind [1992]

Fcontinental CTH4.9

Fmarine CTH1.73

Z_IC

CC

IC/CG Ratio parameterization of Price and Rind [1993]

IC-CG Ratio  CC4.0

Z_CG

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Alternative schemes
Alternative Schemes

CTH MFLUX PRECON

flashes/sec/box

July OTD-LIS July 2004

flashes/sec/box

flashes/sec/box

  • MFLUX and PRECON params [Allen and Pickering 2002] recreate global distribution poorly with GEOS4 fields

  • CTH [Price and Rind 1992] (including near-land) fits overall distribution but fails to capture relative flash rates

flashes/sec/box

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Regional redistribution
Regional Redistribution

  • Scaling done at regional level allows model to drive interannual flashrate variability

  • “v1” & “v2” redistribution product: 15 monthly regions with

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Improvements from redist
Improvements from Redist

NO SCALING

REG SCALING

July 2004

Increased Obs-to-Model correlations in lightning flash rate, particularly during summer months

But rectilinear regions create discontinuities and

OTD-LIS July

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Improved regional redistribution
Improved Regional Redistribution

k-means clustering: Comp. efficient algorithm to allow data-driven regional selection by iteratively minimizing distances between all data and k cluster centroids in an n-dimensional space

k = 20

20 total regions in space and time based on proximity in month, OTD-LIS(1995-2005 avg.) obs, GEOS-Chemoutput (1995-2005 avg.), and latitude.

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Improved regional redistribution1
Improved Regional Redistribution

k-means clustering: Comp. efficient algorithm to allow data-driven regional selection by iteratively minimizing distances between all data and k centroids in an n-dimensional space

k = 20

20 total regions in space and time based on proximity in month, OTD-LIS(1995-2005 avg.) obs, GEOS-Chemoutput (1995-2005 avg.), and latitude.

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Improved regional redistribution2
Improved Regional Redistribution

k-means clustering: Comp. efficient algorithm to allow data-driven regional selection by iteratively minimizing distances between all data and k centroids in an n-dimensional space

k = 20

20 total regions in space and time based on proximity in month, OTD-LIS(1995-2005 avg.) obs, GEOS-Chemoutput (1995-2005 avg.), and latitude.

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


K means clustering
k-means Clustering

Significant improvement in overall distribution and preventing discontinuities, while drastically reducing annual number of regions from 12 x 15 = 180 (v2) to 20 (v3).

OTD-

LIS

v2

v3

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Clustered redistribution
“Clustered” Redistribution

Averaged model to climatology R= 0.92

Flashes/km2/6hr

* 500 mol/fl in the N Midlats [Hudman et al 2007a]

* 280 mol/fl in the tropics to match 4.4Tg tropics [Martin et al 2007]

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


Lightning nox nl mod f
lightning_nox_nl_mod.f

input.geos Options

Diagnostic Options

Individual NOx sources : ---

=> Use aircraft NOx? : F

=> Use lightning NOx? : T

=> OTD reg redist? : T

=> OTD local redist?: F

=> Use CTH param? : T

=> Use MFLUX param? : F

=> Use PRECON param?: F

%%% DIAGNOSTIC MENU %%% :

ND56: Lightning flashes : 1 all

Category: LFLASH-$

Tracer Names: L-RATE, IC-RATE, CG-RATE

Tracer Numbers: 42001, 42002, 42003

Category: NOX-LI-$

Tracer Names: NOx

Tracer Numbers: 1001

Lee T. Murray

Harvard Atmospheric Chemistry Modeling Group


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