Assessing the Parameterization of NOx Emissions By Lightning

in a Chemical Transport Model with HNO3 Columns from IASI

Matthew Cooper1

Randall Martin1,2, Catherine Wespes3,

Pierre-Francois Coheur3, Cathy Clerbaux3,4, Lee Murray5

1. Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada.2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA3. Spectroscopie de l’Atmosphère, Chimie Quantique et Photophysique, Université Libre de Bruxelles, Brussels, Belgium4. Sorbonne Universités, UPMC Univ. Paris 06; Université Versailles St-Quentin; CNRS/INSU, LATMOS-IPSL, Paris, France5. NASA Goddard Institute for Space Studies and Lamont-Doherty Earth Observatory of Columbia University, NY, USA

𝑁𝑂 𝑁𝑂2

𝐻𝑂2

𝑂3

𝐶𝑂

𝐻𝑁𝑂3

20-24 Tg

3-13 Tg

4-15 Tg

4-8 Tg

Global NOx Emissions Have Significant Uncertainty.Can Be Constrained Using HNO3 Observations.

𝑂𝐻

[Cooper et al., JGR 2014]

IASI Satellite Provides Global HNO3 Columns.

IASI – A Nadir-viewing FTS

Global coverage 2x daily

Provides total column HNO3

Measurements over remote Pacific Ocean used alongside GEOS-Chem CTM to extract tropospheric portion of column

IASI Annual Mean Tropospheric HNO3 Column

[Cooper et al., JGR 2014]

IASI Annual Mean Total Atmospheric HNO3 Column

0 0.5 1.0 1.5 2.0 2.5 3(molec/cm2) x1020

0 0.5 1.0 1.5 2.0 2.5 3(molec/cm2) x1019

GEOS-Chem HNO3 Lower Over Southeast Asia

IASI Annual Mean Tropospheric HNO3 Column

GEOS-Chem Annual Mean Tropospheric HNO3 Column

IASI – GEOS-Chem Percent Difference

mo

lec/

cm2

mo

lec/

cm2

Perc

ent

IASI: Nadir-viewing FTS Satellite instrument

GEOS-Chem: Global chemical transport model

GEOS-Chem too low, orIASI too high?

[Cooper et al., JGR 2014]

Bias Due to Model Underestimating HNO3 in SE Asia

• Bias observed by multiple instruments, across large vertical region

[Cooper et al., JGR 2014]

* HIRDLS - Limb-viewing radiometer * ACE-FTS - Solar occulation FTS * Aircraft –PEM West B, PEM Tropics A campaigns *

Lightning NOx is Most Likely Bias Source

•No error in CO gives confidence in anthropogenic and biomass burning emissions

•Deposition processes also ruled out via model studies

• Lightning emits NOx but not CO

[Cooper et al., JGR 2014]

•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]

Sim

ula

ted

IC/C

G F

lash

Rat

io

Some Regionally Varying Lightning Properties that could Affect SE Asia

[Cooper et al., JGR 2014]

Lightning Properties Observed by OTD/LIS

Simulated IC/GC Flash Ratio

The GEOS-Chem Lightning Parameterization

Prescribed NOx/flash(260 mol/flash)

Flash rates match satellite observations

Prescribed vertical profiles

Emissions added

to GEOS-Chem

4°x5° grid boxes

[Cooper et al., JGR 2014]

•Early subgrid plume has high NOx concentration

• Leads to rapid HNO3 production, lower OPE

• This is not represented in the model

LNOx Plumes have Sub-Grid Spatial Scale.LNOx Chemistry is Non-linear

Reality

In GEOS-Chem

[Kleinmann et al 2002]

(OP

E)

[Cooper et al., JGR 2014]

A Simple LNOx Plume Pre-processor

GC Grid BoxNOx

HNO3 + 15O3

Current Mechanism With Pre-Processing

• Adding 0.5 Tg N to Southeast Asia gives better agreement

GC Grid Box

NOx

-1.0 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0

HNO3 Tropospheric Column(IASI – Standard GEOS-Chem)/IASI (IASI – GC w/ PreProcessor)/IASI

92% Bias 6% Bias

[Cooper et al., JGR 2014]

Conclusions

• Tropospheric HNO3 from IASI valuable for understanding NOx sources

• GEOS-Chem underestimates HNO3 in Southeast Asia

• Lightning NOx is most likely contributor to bias

• Developed representation of early stage of concentrated lightning NOx

plume

• A preprocessor for early stages of plume improves the simulation

[Cooper et al., JGR 2014]

LNOx Plume Pre-processor VS

Prescribed Flash Yield

• Adding 0.5 Tg N to Southeast Asia gives better agreement

OzonesondeStandard3.5x Nox

Pre-Process

HNO3 Tropospheric Column(IASI – Standard GEOS-Chem)/IASI

(IASI –GEOS-Chem w/ Pre-Processor)/IASI