Lightning NOx Source Emissions in GEOS-Chem

Lightning NOxLightning NOx Source Source Emissions in GEOS-ChemEmissions in GEOS-Chem

Lee T. MurrayLee T. MurrayApril 12, 2007April 12, 20073rd GEOS-Chem Users’ Meeting3rd GEOS-Chem Users’ MeetingThanks to: Rynda Hudman, Bob Yantosca, Daniel Jacob, Thanks to: Rynda Hudman, Bob Yantosca, Daniel Jacob, Jennifer Logan, Eric Leibensperger, Folkert Boersma, Jennifer Logan, Eric Leibensperger, Folkert Boersma, and othersand others

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Lightning:An Important Source of NOx

[Hudman et al 2007a]

NOx O3

0.0 0.2 0.4 0.6ppbv

0 20 40 60 80 100ppbv

ModelObs

~50Total

0.1-1 (0.4)N2O Degradation

0.7-1 (0.7)Aviation

1-16 (5.5)Soil Emissions

1-20 (5-7)Lightning

4-24 (10)Biomass Burning

28-32 (28)Fossil Fuel Burning

Tg N/yrCurrent Annual NOx Source

[Schumann and Huntrieser 2007]

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Global Lightning DistributionOptical Transient Detector (May 1995 -- Mar

2000)Lightning Imaging Sensor (Dec 1997 --

present)Combined HR Monthly Climatology

flashes / sec / box

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Original Scheme(pre-v7.02.04)

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

LNOx Parameterization

[Pickering 1998]

6 Tg N / yr[Martin et al 2002]

[Price and Rind 1992]

Scaled to CTH

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Flashrate Parameterization

Z_IC

Z_CG

CTH

CC

Flashrate parameterization of Price and Rind [1992]

Fcontinental CTH4.9

Fmarine CTH1.73

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

IC-CG Ratio CC4.0

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Alternative Schemes CTH MFLUX PRECON

Ju

ly O

TD

-LIS

J

uly

2004

flashes/sec/box flashes/sec/box 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

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Regional Redistribution

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

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

⎟⎟⎠

⎞⎜⎜⎝

⎛

⎟⎟⎠

⎞⎜⎜⎝

⎛

=

Flashes GEOS Global

Flashes GEOSRegion

Flashes OTD Global

Flashes OTDRegion

torScalingFac

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Improvements from RedistNO SCALING REG SCALING

July 2004

OTD-LIS July

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

But rectilinear regions create discontinuities and

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Improved Regional Redistributionk-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-Chem output (1995-2005 avg.), and latitude.

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Improved Regional Redistributionk-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-Chem output (1995-2005 avg.), and latitude.

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

Improved Regional Redistributionk-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-Chem output (1995-2005 avg.), and latitude.

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

k-means Clustering

v2 v3

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

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

“Clustered” Redistribution

* 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]

Flashes/km2/6hr

Averaged model to climatology R = 0.92 Avg GC Monthly LNOx 1995-2006

[TgN/yr]

Jan 0.4261

Feb 0.3790

Mar 0.4456

April 0.4479

May 0.5584

June 0.6831

July 0.7654

Aug 0.7262

Sept 0.5587

Oct 0.5524

Nov 0.4916

Dec 0.4349

Total 6.4693

Lee T. MurrayHarvard Atmospheric Chemistry Modeling Group

April 12, 20073rd GEOS-Chem Users’ Meeting

lightning_nox_nl_mod.fIndividual 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-RATETracer Numbers: 42001, 42002, 42003

Category: NOX-LI-$Tracer Names: NOxTracer Numbers: 1001

input.geos Options Diagnostic Options