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1
Status of the LBLRTM Forward Model for Passive Remote Sensing
Mark Shephard, Vivienne Payne, Karen Cady-Pereira andTony Clough
Workshop on Advanced High Spectral Resolution Infrared ObservationsUniversity of Wisconsin
26-28 April 2006
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Topics
• Status of LBLRTM Analytic Jacobian• Temperature and Emissivity of the Surface• Temperature Profiles• Species Profiles• Upwelling/Downwelling
• Status of LBLRTM for Passive Remote Sensing• Temperature• Retrieval of Spectroscopic Parameters from
High Resolution Spectral Observations• SHIS,TES, AIRS, AERI
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Temperature Jacobians: Level 8Emissivity = 0.9999Reflectivity = 0.0001
Temperature Jacobian Lvl 8
-1.0E-8
-5.0E-9
0.0E+0
5.0E-9
1.0E-8
1.5E-8
2.0E-8
2.5E-8
-5.0E-10
0.0E+0
5.0E-10
1.0E-9
1.5E-9
2.0E-9
2.5E-9
3.0E-9
600 650 700 750 800 850 900 950 1000 1050 1100dR
_dT
Diff
eren
ce e
xpan
ded
* 10
(W
/(cm
^2 s
r cm
-1 K
Wavenumber
AJ_Lvl_8
Finite Diff
(AJ - Finite Diff)-1.0E-8
-5.0E-9
0.0E+0
5.0E-9
1.0E-8
1.5E-8
2.0E-8
2.5E-8
-5.0E-10
0.0E+0
5.0E-10
1.0E-9
1.5E-9
2.0E-9
2.5E-9
3.0E-9
600 650 700 750 800 850 900 950 1000 1050 1100
dR_d
T D
iffer
ence
exp
ande
d * 1
0
(W/(c
m^2
sr c
m-1
K)
Wavenumber (cm-1)
Finite Diff
AJ Lvl 8
AJ - Finite Diff
Emissivity = 0.0001Reflectivity = 0.9999Temperature Jacobian Lvl 8
Atmosphere:CAMEX Case27 Levels0-20 km
Upwelling at 20 km
-4.0E-9
-2.0E-9
0.0E+0
2.0E-9
4.0E-9
6.0E-9
8.0E-9
1.0E-8
1.2E-8
-2.0E-10
0.0E+0
2.0E-10
4.0E-10
6.0E-10
8.0E-10
1.0E-9
1.2E-9
1.4E-9
600 650 700 750 800 850 900 950 1000 1050 1100
dR_d
T D
iffer
ence
exp
ande
d *
10
(W/
Wavenumber
lblrtm_FD_DN_00_008
lblrtm_AJ_DN_00_008
lblrtm_AJ_00_008 - lblrtm_FD_DN_00_008
Clough et al.; 14 March 2006
Downwelling at the Surface
Temperature Jacobian Lvl 8
e.g. AERI
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Water Vapor Jacobians: Level 2
Atmosphere:CAMEX Case27 Levels0-20 km
Upwelling at 20 km
-1.4E-7
-1.2E-7
-1.0E-7
-8.0E-8
-6.0E-8
-4.0E-8
-2.0E-8
0.0E+0
2.0E-8
-2.0E-9
0.0E+0
2.0E-9
4.0E-9
6.0E-9
8.0E-9
1.0E-8
1.2E-8
1.4E-8
600 650 700 750 800 850 900 950 1000 1050 1100
dR_d
lnQ
Diff
eren
ce e
xpan
ded
* 10
(W
/(cm
^2 s
r cm
-
Wavenumber (cm-1)
LVL 2 Finite Diff
AJ Level 2
AJ - Finite Diff
Emissivity = 0.9999Reflectivity = 0.0001
TOA Water Vapor JacobianLevel 2
-4.0E-7
-2.0E-7
0.0E+0
2.0E-7
4.0E-7
6.0E-7
8.0E-7
1.0E-6
1.2E-6
1.4E-6
1.6E-6
1.8E-6
2.0E-6
2.2E-6
-2.0E-8
0.0E+0
2.0E-8
4.0E-8
6.0E-8
8.0E-8
1.0E-7
1.2E-7
1.4E-7
1.6E-7
1.8E-7
2.0E-7
2.2E-7
2.4E-7
600 650 700 750 800 850 900 950 1000 1050 1100
dR_d
lnQ
Diff
exp
ande
d *1
0
(W/(c
m^2
sr c
m-1
)
Finite Diff Lvl 2
AJ_TOA_Lvl2
AJ - Finite_Diff
Emissivity = 0.0001Reflectivity = 0.9999
TOA Water Vapor JacobianLevel 2
Downwelling at the Surface
Water Vapor Jacobian
-4.0E-7
-2.0E-7
0.0E+0
2.0E-7
4.0E-7
6.0E-7
8.0E-7
1.0E-6
1.2E-6
1.4E-6
1.6E-6
-2.0E-8
0.0E+0
2.0E-8
4.0E-8
6.0E-8
8.0E-8
1.0E-7
1.2E-7
1.4E-7
1.6E-7
1.8E-7
600 650 700 750 800 850 900 950 1000 1050 1100
dR_d
T D
iffer
ence
exp
ande
d * 1
0
(W/
Wavenumber
lblrtm_FD_DN_01_002
lblrtm_AJ_DN_01_002
lblrtm_AJ_01_002 - lblrtm_FD_DN_01_002
Clough et al.; 14 March 2006
e.g. AERI
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What is ‘Truth’?
• Spectral Residuals are Key!
• Consistency within a band system– Focus of this presentation
• Consistency between bands– AIRS ν2 and ν3 bands to investigate consistency for CO2
• Consistency between species– TES: temperature from O3 and H2O consistent with CO2 ; N2O
• Consistency between instruments- SHIS - MIPAS- AIRS - ACE- TES
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Spectral Radiance Measurements
• The retrieval of atmospheric parameters with InfraRed Remote Sensing is a Poorly Posed Problem
• High Accuracy in the Forward Model and the Measured Radiancesis Essential
• Truth at the Level Required is not readily Available- sonde accuracies; spatial and temporal sampling
- laboratory measurements
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Aura Validation Experiment :Nov. 7, 2004 : Gulf of Mexico
TES : 8 x 5 kmSpectral resolution: 0.06 cm-1
Nadir19:25 UTC
SHIS : ~ 2 kmSpectral resolution: 0.48 cm-1
TES UnderflightAltitude of 18 km
SHIS scans - averaged nine ~2 km circles TES nadir scan - average of the sixteen 0.5 x 5km
rectangular pixels from overpass
AVE Observations to Investigate Line-by-line Calculations
Brightness Temperature (K) @ 1105 cm -1
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TES - SHIS Radiance Comparison
• TES Convolved to SHIS ILS
• {TES - LBLRTM(TES Geometry)} - {SHIS - LBLRTM(SHIS Geometry)}
TES CO2 Filter: 2B1
TES Ozone Filter: 1B2
TES Water Filter: 2A1
Error in O3 above SHIS
Error in CO2 above SHIS
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Reduction of Residuals in ν2 Region
Simultaneous Retrieval of Temperature and Line Parameters
• For each Vibration-Rotation Band (8 3)– Line Strength (3 parameters)– Line Width (2 parameters)
• Global– P - R Line Coupling (Hartmann) (scaling)– Q Line Coupling (Hartmann) (scaling)– Halfwidth Temperature Dependence– CO2 Continuum (scaling)
→
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Corrections to CO2 line intensities and widths
• Form of correction to line intensities:
Sret = SHITRAN (1+ a0 ) (1+ a1m + a2m2 )2
Wret =WHITRAN (1+ b0 + b1 | m |)
m=−J" m=J"+1
• Form of correction to line widths:
• m is related to the upper state local quantum number.• For the P branch For the R branch
Retrieval parameters: a0, a1, a2, b0 , b1
Linda Brown
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Line Coupling Parameters for the 5 < 2 Band
-3.25
-3.00
-2.75
-2.50
-2.25
-2.00
-1.75
-1.50
-1.25
-1.00
-0.75
-0.50
-0.25
0.00
0.25
-0.07
-0.05
-0.03
-0.01
0.01
0.03
0.05
0.07
715 717 719 721 723 725
630 650 670 690 710 730 750 770 790
P, R
Bra
nch
Ys
Wavenumber (cm-1)
Wavenumber (cm-1)
Q Branch Hartmann et al.
Q Branch Hoke et al.
P Branch Hartmann et al.
R Branch Hartmann et al.
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Effect of Line Coupling
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Sensitivity Studies (Jacobians)
• a0, a1, a2, b1 perturbed to change intensities/widths in HITRAN line file.
• Values chosen to induce 10% change in intensity/width at J’’~ 40.
• Perturbation spectra calculated for each parameter, each band.
Example: 2 1 band
Reference spectrum
a0
a1
a2
b1
Wavenumber [cm-1]
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SHIS AVE Retrieval Results
Scatter plots of Brightness Temperature vs. Residuals(Obs - Calc.) binned in 20 cm-1
intervals from the CO2 v2 region
GM
AO
Tem
pO
nly
Tem
p &
S
pect
rosc
opy
Retrieval Spectral Region
15
Detail View Before Spectroscopy
• Further reduce residuals in the CO2 v2 spectral region
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SHIS AVE Temperature Retrieval Results
Temp & SpectroscopyTemp Only
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Averaging Kernels
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SHIS AVE CO2 Retrieved Parameters
Band Band center (cm-1)
Retrieved Parameter
3 2 618.03 a0b0
1%1%
2 1 667.38 a2 - 2%
5 2 720.81 a2b0
- 4%3%
ALL Bands CO2CNTMN
2x
P/R Line Coupling - 50%
Sret = SHITRAN (1 + a0 ) (1+ a1m + a2m2)2
Wret = WHITRAN(1 +b0 +b1 |m|)
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What is ‘Truth’?
• Spectral Residuals are Key!
• Consistency within a band system– Focus of this presentation
• Consistency between bands– AIRS ν2 and ν3 bands to investigate consistency for CO2
• Consistency between species– TES: temperature from O3 and H2O consistent with CO2 ; N2O
• Consistency between instruments- SHIS - MIPAS- AIRS - ACE- TES
20
AIRS: new spectroscopyAtmosphere: sonde/adjusted ecmwf
21
‘Truth’ isn’t ubiquitous- Yet!
• Spectral Residuals are Key!
• Consistency within a band system– Focus of this presentation
• Consistency between bands– AIRS ν2 and ν3 bands to investigate consistency for CO2
• Consistency between species– TES: temperature from O3 and H2O consistent with CO2 ; AIRS: CO2 , N2O
• Consistency between instruments- SHIS - MIPAS- AIRS - ACE- TES
22
Back-up slides to follow………
23
CO2 Line Shape
Chi function: The spectral function by which theLorentz line shape (impact) must be multiplied to obtain the “true” line shape.Sub-Lorentzian chi function accounts for the duration of collision effects.
0.0
0.2
0.4
0.6
0.8
1.0
0 5 10 15 20 25
Chi
Fun
ctio
n
Wavenumbers from Line Center (cm-1)
Clough et al., 1978Cousin (a) N2 296KCousin (c) N2 238KChi_LBLRTM_v_8
LBLRTM Chi Function for CarbonDioxide
impact
Continuum: Line contributions 25 cm-1
beyond line center
Lorentz (impact)lblrtm_v6.01
lblrtm_v8.2
CO2 Continuum
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Perturbations to line intensities/widths: 3 2 band
a0
a1
a2
b1
Reference spectrum
25
Perturbations to line intensities/widths: 2 1 band
a0
b1
a1
a2
Reference spectrum
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Perturbations to line intensities/widths: 4 2 band
a0
b1
a2
a1
Reference spectrum
27
Perturbations to line intensities/widths: 5 2 band
Reference spectrum
a1
a0
a2
b1
28
Perturbations to line intensities/widths: 6 3 band
a0
b1
a2
a1
Reference spectrum
29
Perturbations to line intensities/widths: 7 4 band
a0
b1
a2
a1
Reference spectrum
30
Perturbations to line intensities/widths: 8 5 band
a0
b1
a2
a1
Reference spectrum
31
Perturbations to line intensities/widths: 8 4 band
a0
b1
a2
a1
Reference spectrum
32
Averaging Kernels
33
Correlation matrix (H-1)
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LBLRTM Validation : TES CO2 v2 Filter
TES Obs.
TES - LBLRTM
TES(SHIS ILS) - LBLRTM
SHIS - LBLRTM
CO2 v2
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SHIS AVE CO2 Width and Intensity Retrieval Results
Band Band center (cm-1)
Retrieved value
3 2 618.03 a0a1a2b1
-0.0053-0.000510.0000040.00055
2 1 667.38 a0a1a2b1
0.0770.00022-0.000039-0.00077
5 2 720.81 a0a1a2b1
0.0150.00028-0.000016-0.00075
Sret = SHITRAN (1 + a0) (1 + a1m + a2m2)2
Wret = WHITRAN(1+b1|m|)