OMI NO observations of boreal forest fires
Transcript of OMI NO observations of boreal forest fires
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OMI NO2 observations of boreal forest fires
Nicolas Bousserez, Randall V. Martin, Lok Lamsal,
and the ARCTAS team
Dalhousie University Halifax, Nova Scotia
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ARCTAS experiment Spring/Summer 2008
Summer phase (June, 18 - July, 13)
Boreal forest fires over center Canada
DC-8 measurements:
NOx concentrations
Aerosols optical properties
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Boreal fires emissions over ‘Alberta’ domain
OMI (DOMINO KNMI) NO2 tropospheric columns
MODIS Aerosol Optical Depth (AOD)
MODIS fire pixels
ARCTAS summer phase averaged NO2 and AOD tropospheric columns
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Summer Phase (18/06 to 13/07)
Tropospheric AOD NO2 Tropospheric Columns
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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
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Bias in GC
GC
DC-8
NO2 (pptV)
Ext
inct
ion
coef
ficie
nt (5
50nm
) (M
m-1
)
-DC-8 criteria:
HCN > 500 pptV NOx/NOy > 40%
-GC criteria:
CObb > 90% Total CO (sensitivity runs)
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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 factor Scattering weights
Ωs = Slant Column Ωv = Vertical Column AMF = Air Mass Factor
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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)
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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 (M
OD
IS)
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OMI NO2 / GCstd NO2
AM
F co
rrec
ted
/ AM
F st
anda
rd
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
OMI NO2 - GCstd NO2 > 0.5 x GCstd NO2 r = -0.68 y = -0.10 x + 0.76 nb pts = 11
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