OMI NO2 observations of boreal

forest fires

OMI NO2 observations of boreal

forest fires

Nicolas Bousserez,Randall V. Martin, Lok Lamsal,

and the ARCTAS team

Dalhousie UniversityHalifax, Nova Scotia

ARCTAS experimentSpring/Summer 2008ARCTAS experimentSpring/Summer 2008

Summer phase (June, 18 - July, 13)

Boreal forest fires over center Canada

DC-8 measurements:

NOx concentrations

Aerosols optical properties

Boreal fires emissions over ‘Alberta’ domainBoreal fires emissions over ‘Alberta’ domain

OMI (DOMINO KNMI) NO2 tropospheric columns

OMI (DOMINO KNMI) NO2 tropospheric columns

MODIS Aerosol Optical Depth (AOD)

MODIS Aerosol Optical Depth (AOD)

MODIS fire pixelsMODIS fire pixels

ARCTAS summer phase averaged NO2 and AOD

tropospheric columns

DC-8 NODC-8 NO22 tropospheric columns & AOD tropospheric columns & AOD

Summer Phase (18/06 to 13/07)

Tropospheric AODNO2 Tropospheric Columns

GEOS-Chem ARCTAS GEOS-Chem ARCTAS NRT SimulationsNRT Simulations

GEOS-Chem v8-01-01

Modifications:

David Streets 2006 emissions over SE Asia & China

FLAMBE daily biomass burning emissions

GEOS-5 Metfields

Horizontal Grid: 2º lat x 2.5º lon

Vertical Grid: Reduced 47 layers

NONO22 vs Aerosol Extinction vs Aerosol Extinction

in biomass burning plumesin biomass burning plumes

Bias in GC

GC

DC-8

NO2 (pptV)

Ext

inct

ion

coef

ficie

nt (

550n

m)

(Mm

-1)

-DC-8 criteria:

HCN > 500 pptVNOx/NOy > 40%

-GC criteria:

CObb > 90% Total CO(sensitivity runs)

Impact of aerosols and GC NO2 profiles on

NO2 retrievals?

Impact of aerosols and GC NO2 profiles on

NO2 retrievals?

AMF with explicit aerosols and clouds correction (LIDORT model)

GEOS-Chem provides NO2 profiles (shape factor) and aerosol optical properties (scattering

weights calculation)

Ωv = Ωs / AMF

Shape factorScattering weights

Ωs = Slant Column

Ωv = Vertical Column

AMF = Air Mass Factor

AMF sensitivity to aerosols & shape factorAMF sensitivity to aerosols & shape factor

AMF Aerosol Correction Factor ~ + 7.5 %

AMF Shape Factor Correction Factor ~ - 35 %

Shape factor impact dominates

AMF/AMFw/o aerosols

AMF/AMFw/o bb emissions

SSA

Mostly Scattering Aerosols

DC-8

GC

Single Scattering Albedo(SSA)

Significant improvement of the NOSignificant improvement of the NO22/AOD /AOD

relationship using GC shape factorsrelationship using GC shape factors

DC-8

GC

KNMI(DOMINO)

KNMI_gc(w/ GC profiles)

Correction over boreal fires: NO2 KNMI_GC ~ 2*NO2 KNMI

BB criteria:data points close to MODIS

hot spot pixels(r < 10 km)

NO2

AO

D (

MO

DIS

)

OMI NO2 / GCstd NO2

AM

F c

orre

cted

/ A

MF

sta

ndar

d

Linear relationship between AMF correction factor and OMI NO2/GCstd NO2 ratio?

Real-time correction to measured NO2 columns over boreal fires areas

In practice, exclude data when AMFcorrected/AMFstandard < 0.2

Proposed correction for OMI tropospheric NO2 Proposed correction for OMI tropospheric NO2 columns over boreal firescolumns over boreal fires

OMI NO2 - GCstd NO2 > 0.5 x GCstd NO2 r = -0.68y = -0.10 x + 0.76nb pts = 11

Thank youThank you