retrieval of so 2 vertical columns from sciamachy and omi: air mass factor algorithm development...
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Retrieval of SO2 Vertical Columns from SCIAMACHY and OMI: Air Mass Factor Algorithm
Development
Chulkyu Lee, Aaron van Dokelaar, Gray O’Byrne: Dalhousie Univ.Randall V. Martin: Dalhousie Univ. and Harvard-Smithsonian
Nickolay Krotkov: NASA Goddard and UMBCAndreas Richter: Univ. of Bremen
Greg Huey: Georgia TechJohn S. Holloway: NOAA
April 07, 2009 4th GEOS-Chem Users’ Meeting
Harvard University
Scattering weight
Local AMF Calculation
dt(η)
IoIB
Earth Surface
Radiative Transfer Model
Scattering weight
(η) is temperature-dependent cross-section
)(ln)(1
)( B
eG
I
AMF
Calculate ω(η) as function of:• solar and viewing zenith angle (θs, θv)• surface reflectivity, pressure• cloud pressure, aerosol• O3 column:
Atmospheric Chemistry Model:GEOS-Chem (Bey et al. 2001)
For individual scenes
1
)()(T
dSAMFColumnsVertical
ColumnsSlantAMF G
Shape factor
SO2 mixing ratio, CSO2(η)
eta
(η)
2
)()(SO
airCS
USO
currentOUSOCorrO CC
,
,,,
3
3
33)()(
* Based on Palmer et al., JGR, 2001; Martin et al., JGR, 2002
Geometric AMF: )sec()sec( vsGAMF
GEOS-Chem Simulation
GEOS-Chem v8-01-04 - GEOS-4, 30 η vertical levels, 2º latitude by 2.5º longitude - Based on EDGAR inventory - Regional inventories: NEI99, BRAVO, CAC, Streets, EMEP
Update of the eruptive volcanic inventory for 2006 using the database of Global Volcanism Program
(GVP: http://www.volcano.si.edu/)
Recalculation of optical properties for mineral dust using refractive indices of Sinyuk et al., GRL, 2003
- SSA at 300 nm increases by ~0.1 to the range of 0.7-0.9
Shape Factor: GEOS-Chem vs In-situDifferences would change AMF by <10%
In-situ platform DC-8 & C-130
0 2 4 6 8 10 12
1000
900
800
700
600
500
400
300
2000.0 0.8 1.6 2.4
0 2 4 6 8 10 12
1000
900
800
700
600
500
400
300
200
0.0 0.2 0.4 0.6
0 2 4 6 8 10 12
1000
900
800
700
600
500
400
300
200
0 2 4 6 8 10 12
1000
900
800
700
600
500
400
300
200
0 1 2 3
0 1 2 3
Pre
ssur
e [h
Pa]
SO2 Shape Factor [unitless]
INTEX-A: Land GEOS-Chem In-situ
12
152
1721268920978113704253617098138224
In-situ Mixing Ratio [ppbv]
SO2 Shape Factor [unitless]
INTEX-A: Ocean GEOS-Chem In-situ
8
3
3
45978117812181615
In-situ Mixing Ratio [ppbv]
3
3
2
4712121811121113182923
Pre
ssur
e [h
Pa]
SO2 Shape Factor [unitless]
INTEX-B: Houston GEOS-Chem In-situ
SO2 Shape Factor [unitless]
INTEX-B: North Pacific GEOS-Chem In-situ
31
316
353254197220161160115111127151106162283112
In-situ Mixing Ratio [ppbv]
In-situ Mixing Ratio [ppbv]
OMI SO2 AMF for 2006
Calculated at 313.2 nm; Cloud Radiance Fraction < 0.2; SZA < 70 SCIAMACHY AMF at 319.7 nm within 25%
Local AMF Increases Agreement with Aircraft
▲ INTEX-A■ INTEX-B
-0.3 0.0 0.3 0.6 0.9 1.2 1.5 1.8-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-0.3 0.0 0.3 0.6 0.9 1.2 1.5 1.8-0.3
0.0
0.3
0.6
0.9
1.2
1.5
1.8
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
OM
I SO
2 [D
U]
In Situ SO2 [DU]
- - - Reduced major-axis linear fit Y = 1.61X + 0.21 (r = 0.71)
Using constant AMF = 0.36
In Situ SO2 [DU]
- - - Reduced major-axis linear fit Y = 0.95X + 0.05 (r = 0.92)
SC
IAM
AC
HY
SO
2 [D
U]
- - - Reduced major-axis linear fit Y = 1.38X + 0.01 (r = 0.78)
With Old AMF
Using constant AMF = 0.88
- - - Reduced major-axis linear fit Y = 1.12X + 0.06 (r = 0.89)
With New AMF
SO2 Vertical Columns for 2006
Cloud Radiance Fraction < 0.2; SZA < 70
Correlation with
GEOS-Chem (GC)
: Globally r ~0.78
: ~0.84 over US
: ~0.83 over China
GC with OMI AMF within 10% GC with SCIAMACHY AMF
Sensitivity of Retrieved SO2 to ΔEmissions
GEOS-Chem SO2
changes by ×2
OMI SO2 AMFchanges < 30%
Summary
Validation of GEOS-Chem SO2 shape factors with airborne in-situ measurements for INTEX-A and B
: <10% change in AMF
Validation of SO2 vertical columns from SCIAMACHY and OMI with airborne in-situ measurements for INTEX-A and B
: r = 0.9
Large sensitivity of retrieved SO2 to emissions
GEOS-Chem Simulation
GEOS-Chem v8-01-04 -GEOS-4, 30 η vertical levels, 2° latitude by 2.5° longitude - Based on EDGAR inventory - Regional inventories: NEI99, BRAVO, CAC, Streets, EMEP
Update of the eruptive volcanic inventory for 2006
Volcanic Explosivity Index (VEI)a
0 1 2 3
SO2 Emissionb,
Mg/day2.5×10-1 2.25×100 1.7×101 1.15×102
Cloud Column
Heightc
50 m above
crater
550 m above
crater
3000 m
above sea
level
9000 m
above sea
levelaObtained from Global Volcanism Program (GVP: http://www.volcano.si.edu/ );bChin et al. [1996]; cNewhall et al. [1982]
Error Analysis
222222 1 AMFclearAMFcloudcclearcloudAMF ccAMFAMF
c: cloud radiance fraction
AMF error from surface reflectivity, shape factor, aerosol, cloud
(Wenig et al., 2008)
Cloud Radiance Fraction < 0.2; SZA < 70
Polluted: SO2 > 1016 molec/cm2