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HGF — PEL Atmosphere Workshop II
WP1100 — Radiative TransferPast and Future
Franz Schreier, Mayte Vásquez, Thomas TrautmannSebastián Gimeno García, Pascal Hedelt
.DLR — Remote Sensing Technology Institute
Oberpfaffenhofen, GERMANY
April 2013
Remote Sensing Technology Institute WP1100 - Radiative Transfer 1
Outline
1 Past
2 Future
Remote Sensing Technology Institute WP1100 - Radiative Transfer 2
GARLIC (SQuIRRL) for Venus Transit Spectroscopy
Transit June 2004Vacuum Tower TelescopeTenerifeEmergency call:“We have spectra, but no model”
... and SQuIRRL goes to Berlin!P. Hedelt, DLR–PF,Diploma Thesis, 2006
Analysis of CO2 SWIR region:isotope abundances,field-of-view,tangent altitudes, . . .
black: observed; red, blue: modeledcircles: dead pixels
Remote Sensing Technology Institute WP1100 - Radiative Transfer 3
GARLIC — Generic Atmospheric Radiation Lbl Infrared Code
Line shapes: Voigt, VanVleck⌦Doppler, LorentzLine data: HITRAN, HITEMP, GEISA, JPL, . . .Continua: H2O (CKD), CO2, N2, O2, “dry air” (Liebe)Geometries: Limb, uplooking, downlooking (refraction optional)Instruments: Spectral response: FTS, Heterodyne, Fabry–Perot, . . .
Field-of-view: Box, Gauss, Trapez, . . .
Implementation: FORTRAN 2008, all data read from external filesVerification: AMIL2DA (mid IR, !), IRTMW01 (µWave, !, ", #), . . .Jacobians: Automatic differentationExtensions: (multiple) scattering infrared radiative transfer:
M. Vasquez: cloudy planetary atmospheres
Remote Sensing Technology Institute WP1100 - Radiative Transfer 4
GARLIC — Generic Atmospheric Radiation Lbl Infrared Code
Line shapes: Voigt, VanVleck⌦Doppler, LorentzLine data: HITRAN, HITEMP, GEISA, JPL, . . .Continua: H2O (CKD), CO2, N2, O2, “dry air” (Liebe)Geometries: Limb, uplooking, downlooking (refraction optional)Instruments: Spectral response: FTS, Heterodyne, Fabry–Perot, . . .
Field-of-view: Box, Gauss, Trapez, . . .
Implementation: FORTRAN 2008, all data read from external filesVerification: AMIL2DA (mid IR, !), IRTMW01 (µWave, !, ", #), . . .Jacobians: Automatic differentationExtensions: (multiple) scattering infrared radiative transfer:
M. Vasquez: cloudy planetary atmospheres
Remote Sensing Technology Institute WP1100 - Radiative Transfer 4
GARLIC — Recent Advances
SQuIRRL – R.I.P.
Fortran 90 re-implementation ofSQuIRRL
I dynamic array allocationsI easier to maintain: structures
lbl — optimized 8 IRI Humlicek-Weideman VoigtI “multi” grid cross sectionsI multi-threading — OpenMP
CIA collision-induced absorptionWeighting functionsBackground sources: more flexible
Remote Sensing Technology Institute WP1100 - Radiative Transfer 5
GARLIC — Recent Advances
SQuIRRL – R.I.P.
Fortran 90 re-implementation ofSQuIRRL
I dynamic array allocationsI easier to maintain: structures
lbl — optimized 8 IRI Humlicek-Weideman VoigtI “multi” grid cross sectionsI multi-threading — OpenMP
CIA collision-induced absorptionWeighting functionsBackground sources: more flexible
ARTS — GARLIC — KOPRA:– 42 “Garand” atmospheres,– 19 HIRS channels
0 20 40 60!4
!2
0
2
4Ch #15 2235
Fri A
pr
12
17
:43
:34
20
13
!0.5
0
0.5
1
!T
[K
]
Ch # 9 1030
Fri A
pr
12
17
:43
:34
20
13
!0.4
!0.2
0
0.2
0.4Ch # 2 680
Fri A
pr
12
17
:43
:34
20
13
0 20 40 60
H2O [kg/m2]
!2
!1
0
1
2Ch #16 2241
Fri A
pr
12
17
:43
:34
20
13
!2
!1
0
1Ch #12 1529
Fri A
pr
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:43
:34
20
13
!0.4
!0.2
0
0.2
0.4
0.6
0.8Ch # 3 692
Fri A
pr
12
17
:43
:34
20
13
arts!garlicgarlic!koprakopra!arts
0 20 40 60!2
!1
0
1
2Ch #17 2419
Fri A
pr
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:43
:34
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!1
!0.5
0
0.5
1Ch # 7 749
Fri A
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:43
:34
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Remote Sensing Technology Institute WP1100 - Radiative Transfer 5
GARLIC — Recent Advances
SQuIRRL – R.I.P.
Fortran 90 re-implementation ofSQuIRRL
I dynamic array allocationsI easier to maintain: structures
lbl — optimized 8 IRI Humlicek-Weideman VoigtI “multi” grid cross sectionsI multi-threading — OpenMP
CIA collision-induced absorptionWeighting functionsBackground sources: more flexible
Outlook:Continua: MT-CKDFPGA2D/3D atmospheresCollisional narrowing:Rautian, Galatry, . . .Line mixingnon-LTE
Remote Sensing Technology Institute WP1100 - Radiative Transfer 5
Where are we? Oberpfaffenhofen
PhD ThesisRadiative transfer in cloudy planet atmospheresSORTRA = GARLIC + DISORT
SCIA–Venus observations & modeling:Adv. Space Research 2013
Infrared radiative transfer in atmospheres ofEarth-like planets around F, G, K, and M starsInput: “Kitzmann atmospheres”
1 Clear-sky thermal emission spectraand weighting functionsAstronomy & Astrophysics 2013
2 Thermal emission spectrainfluenced by cloudsA&A, hopefully accepted soon!?!
Remote Sensing Technology Institute WP1100 - Radiative Transfer 6
FGKM Star Planets: Weighting Functions
Remote Sensing Technology Institute WP1100 - Radiative Transfer 7
FGKM Star Planets: Lbl vs. Correlated-k
Remote Sensing Technology Institute WP1100 - Radiative Transfer 8
Where are we? Berlin TUB&Adlershof
Some studies with lbl infrared simulations:
P. Hedelt: Venus transit observations 2004 A+A 2011
P. von Paris et al.: Warming the early Earth – CO2 reconsidered PSS 2008
H. Rauer et al.: Potential biosignatures in super-Earth atmospheres I.Spectral appearance of super-Earths around M dwarfs A+A 2011
P. von Paris et al.: Spectroscopic characterization of the atmospheresof potentially habitable planets: GL 581 d as a model case study A+A 2011
L. Grenfell et al.: Sensitivity of biomarkers to changes in chemicalemissions in the Earth’s Proterozoic atmosphere Icarus 2011
P. Hedelt et al.: Spectral features of Earth-like planets and theirdetectability at different orbital distances around F, G, K stars A+A 2013
P. von Paris et al.: Characterization of potentially habitable planets:Retrieval of atmospheric and planetary properties from emissionspectra A+A 2013
Remote Sensing Technology Institute WP1100 - Radiative Transfer 9
Outline
1 Past
2 Future
Remote Sensing Technology Institute WP1100 - Radiative Transfer 10
What’s next???
HGF Alliance “Planetary Evolution and Life” 2008–2013
“Near-term” — “simple” extension of Mayte’s work:I NIR transmission/reflection of cloud covered exoplanetsI Multiple cloud layersI CO2 ice cloudsI Gliese 581 d: impact of clouds?I Fluxes: plane-parallel approximation vs. full sphericalI Clouds: ‘simple” vs. multiple scattering
“Long-term” — remote sensingI Temperature sounding and weighting functions:
(impact of (unknown) CO2 concentration and surface pressure)I Retrieval feasibility studies (cf. PvP A&A 2013)I Analysis of real observations (e.g., hot Jupiters and Neptunes)I . . . . . .
. . . and our neighbors?I Venus transit 2012 ?I Venus, Mars Express?
Remote Sensing Technology Institute WP1100 - Radiative Transfer 11
What’s next???
HGF Alliance “Planetary Evolution and Life” 2008–2013
“Near-term” — “simple” extension of Mayte’s work:I NIR transmission/reflection of cloud covered exoplanetsI Multiple cloud layersI CO2 ice cloudsI Gliese 581 d: impact of clouds?I Fluxes: plane-parallel approximation vs. full sphericalI Clouds: ‘simple” vs. multiple scattering
“Long-term” — remote sensingI Temperature sounding and weighting functions:
(impact of (unknown) CO2 concentration and surface pressure)I Retrieval feasibility studies (cf. PvP A&A 2013)I Analysis of real observations (e.g., hot Jupiters and Neptunes)I . . . . . .
. . . and our neighbors?I Venus transit 2012 ?I Venus, Mars Express?
Remote Sensing Technology Institute WP1100 - Radiative Transfer 11
Retrieval Methodology
Schwarzschild equation (negl. background, clouds, instrument, . . . )
I(⌫) =
Z 1
0dz B
�⌫,T (z)
� @
@zexp
�Z z
0dz 0X
m
km(⌫; p(z 0),T (z 0)) nm(z 0)
!
| {z }@T (⌫;z)/@z
Discretization:finite number m of observations: measurement vector y
quadrature points or expansion coefficients or . . . : state vector x
Nonlinear least squares problem
minx
kIobs � Imod(x)k2
Remote Sensing Technology Institute WP1100 - Radiative Transfer 12
Retrieval Methodology
Schwarzschild equation (negl. background, clouds, instrument, . . . )
I(⌫) =
Z 1
0dz B
�⌫,T (z)
� @
@zexp
�Z z
0dz 0X
m
km(⌫; p(z 0),T (z 0)) nm(z 0)
!
| {z }@T (⌫;z)/@z
Discretization:finite number m of observations: measurement vector y
quadrature points or expansion coefficients or . . . : state vector x
Nonlinear least squares problem
minx
kIobs � Imod(x)k2
Remote Sensing Technology Institute WP1100 - Radiative Transfer 12
Regularization
Discretization of radiative transfer integral equation =)Least squares problem min
x
kF(x) � yk2
Ill posed problemI Data cannot provide sufficient informationI Extremely strong sensitivity of solution to perturbations of data
�! Need additional information about the solutionGeneralization of the minimization problem
I Optimal estimation (Rodgers 1976):Statistically combine a priori and retrieved profile
minx
⇣(F(x)� y)T S�1
y (F(x)� y) + (x � xa)T S�1
a (x � xa)⌘
I Tikhonov regularization (1963):Introduce ’smoothness’ conditions on profile
minx
�kF(x) � yk2+�2kLxk2�
� Fit of parameterized function (e.g. column density fit)=) reduced number of unknowns
Remote Sensing Technology Institute WP1100 - Radiative Transfer 13
Regularization
Discretization of radiative transfer integral equation =)Least squares problem min
x
kF(x) � yk2
Ill posed problemI Data cannot provide sufficient informationI Extremely strong sensitivity of solution to perturbations of data
�! Need additional information about the solutionGeneralization of the minimization problem
I Optimal estimation (Rodgers 1976):Statistically combine a priori and retrieved profile
minx
⇣(F(x)� y)T S�1
y (F(x)� y) + (x � xa)T S�1
a (x � xa)⌘
I Tikhonov regularization (1963):Introduce ’smoothness’ conditions on profile
minx
�kF(x) � yk2+�2kLxk2�
� Fit of parameterized function (e.g. column density fit)=) reduced number of unknowns
Remote Sensing Technology Institute WP1100 - Radiative Transfer 13
Regularization
Discretization of radiative transfer integral equation =)Least squares problem min
x
kF(x) � yk2
Ill posed problemI Data cannot provide sufficient informationI Extremely strong sensitivity of solution to perturbations of data
�! Need additional information about the solutionGeneralization of the minimization problem
I Optimal estimation (Rodgers 1976):Statistically combine a priori and retrieved profile
?¿? a priori for exo-planets ?¿?
I Tikhonov regularization (1963):Introduce ’smoothness’ conditions on profile
minx
�kF(x) � yk2+�2kLxk2�
� Fit of parameterized function (e.g. column density fit)=) reduced number of unknowns
Remote Sensing Technology Institute WP1100 - Radiative Transfer 13
GARLIC and Atmospheric Inverse Problems
BIRRA Beer InfraRed Retrieval Algorithm
column density nonlinear leastsquares for nadir nir (SCIAMACHY)
CERVISAColumn EstimatoR Vertical Ir Sounding Atmosphere
column density nonlinear leastsquares for nadir tir (AIRS, IASI, . . . )VINO Versatile Inversion for Nadir Observations
GARLIC + DRACULA for nadirsounding profiles (IASI, GOSAT)PILS Profile Inversion for Limb Sounding
TELIS — TeraHertz Limb Sounder
Remote Sensing Technology Institute WP1100 - Radiative Transfer 14
GARLIC and Atmospheric Inverse Problems
BIRRA Beer InfraRed Retrieval Algorithm
column density nonlinear leastsquares for nadir nir (SCIAMACHY)CERVISAColumn EstimatoR Vertical Ir Sounding Atmosphere
column density nonlinear leastsquares for nadir tir (AIRS, IASI, . . . )
VINO Versatile Inversion for Nadir Observations
GARLIC + DRACULA for nadirsounding profiles (IASI, GOSAT)PILS Profile Inversion for Limb Sounding
TELIS — TeraHertz Limb Sounder
−50 −25 0 25 50Latitude [dg]
0
1e+18
2e+18
3e+18
4e+18
VCD
[mol
ec/c
m2 ]
27. October 2003
Thu
Jul 2
2 13
:19:
06 2
010
0
1e+18
2e+18
3e+18
4e+18
VCD
[mol
ec/c
m2 ]
9. October 2003
Thu
Jul 2
2 13
:19:
06 2
010
AIRX2RET0.8 * AIRS−cervisa1.4 * SCIA−birra1.4 * <SCIA−birra>
0
1e+18
2e+18
3e+18
4e+18
VCD
[mol
ec/c
m2 ]
Thu
Jul 2
2 13
:19:
06 2
010
Remote Sensing Technology Institute WP1100 - Radiative Transfer 14
GARLIC and Atmospheric Inverse Problems
BIRRA Beer InfraRed Retrieval Algorithm
column density nonlinear leastsquares for nadir nir (SCIAMACHY)CERVISAColumn EstimatoR Vertical Ir Sounding Atmosphere
column density nonlinear leastsquares for nadir tir (AIRS, IASI, . . . )VINO Versatile Inversion for Nadir Observations
GARLIC + DRACULA for nadirsounding profiles (IASI, GOSAT)
PILS Profile Inversion for Limb Sounding
TELIS — TeraHertz Limb Sounder
0 2e+12 4e+12 6e+12Number Density [molec/cm3]
0
20
40
60
80
Altit
ude
Regularization −−− IASI Ozone
Thu
Jul 2
2 14
:17:
21 2
010
Runge−KuttaTikhonovExact profileInitial guess
A. Doicu, M. Hess, M. Szopa
Remote Sensing Technology Institute WP1100 - Radiative Transfer 14
GARLIC and Atmospheric Inverse Problems
BIRRA Beer InfraRed Retrieval Algorithm
column density nonlinear leastsquares for nadir nir (SCIAMACHY)CERVISAColumn EstimatoR Vertical Ir Sounding Atmosphere
column density nonlinear leastsquares for nadir tir (AIRS, IASI, . . . )VINO Versatile Inversion for Nadir Observations
GARLIC + DRACULA for nadirsounding profiles (IASI, GOSAT)PILS Profile Inversion for Limb Sounding
TELIS — TeraHertz Limb Sounder
0 1 2 3 4 5O
3 VMR [ppmv]
15
20
25
30
35
40
Alt
itu
de
[km
]
SMILES-1SMILES-2TELIS
5e+09 5.5e+09 6e+09 6.5e+09 7e+09DSB IF frequency [Hz] (LO = 619.1 GHz)
0
5e-15
1e-14
1.5e-14
2e-14
2.5e-14
Radi
ance
[W /
(m2 sr
Hz)
]
10.0 km13.0 km16.0 km19.0 km22.0 km25.0 km28.0 km31.0 km
with Greybody Fitting
Jian Xu
Remote Sensing Technology Institute WP1100 - Radiative Transfer 14
Exoplanets Retrievals — Additional Challenges
EarthClimatologies etc. forinitial guess and/or a priori
Local view(1D atmosphere sufficient)Spectral range, resolution,noise “problem specific”Observations repeatable“Easy” verification & validationEverything known (almost)
Exoplanetsno climatologies!unknown constituents?atmos model �! init guess?
Global view:disk-averaged spectrum“Sub-optimal” spec range,low resolution, high noiseA single observation?Validation ???Everything unknown
Remote Sensing Technology Institute WP1100 - Radiative Transfer 15
Exoplanets Retrievals — Additional Challenges
EarthClimatologies etc. forinitial guess and/or a priori
Local view(1D atmosphere sufficient)
Spectral range, resolution,noise “problem specific”Observations repeatable“Easy” verification & validationEverything known (almost)
Exoplanetsno climatologies!unknown constituents?atmos model �! init guess?Global view:disk-averaged spectrum
“Sub-optimal” spec range,low resolution, high noiseA single observation?Validation ???Everything unknown
Remote Sensing Technology Institute WP1100 - Radiative Transfer 15
Exoplanets Retrievals — Additional Challenges
EarthClimatologies etc. forinitial guess and/or a priori
Local view(1D atmosphere sufficient)Spectral range, resolution,noise “problem specific”
Observations repeatable“Easy” verification & validationEverything known (almost)
Exoplanetsno climatologies!unknown constituents?atmos model �! init guess?Global view:disk-averaged spectrum“Sub-optimal” spec range,low resolution, high noise
A single observation?Validation ???Everything unknown
Remote Sensing Technology Institute WP1100 - Radiative Transfer 15
Exoplanets Retrievals — Additional Challenges
EarthClimatologies etc. forinitial guess and/or a priori
Local view(1D atmosphere sufficient)Spectral range, resolution,noise “problem specific”Observations repeatable
“Easy” verification & validationEverything known (almost)
Exoplanetsno climatologies!unknown constituents?atmos model �! init guess?Global view:disk-averaged spectrum“Sub-optimal” spec range,low resolution, high noiseA single observation?
Validation ???Everything unknown
Remote Sensing Technology Institute WP1100 - Radiative Transfer 15
Exoplanets Retrievals — Additional Challenges
EarthClimatologies etc. forinitial guess and/or a priori
Local view(1D atmosphere sufficient)Spectral range, resolution,noise “problem specific”Observations repeatable“Easy” verification & validation
Everything known (almost)
Exoplanetsno climatologies!unknown constituents?atmos model �! init guess?Global view:disk-averaged spectrum“Sub-optimal” spec range,low resolution, high noiseA single observation?Validation ???
Everything unknown
Remote Sensing Technology Institute WP1100 - Radiative Transfer 15
Exoplanets Retrievals — Additional Challenges
EarthClimatologies etc. forinitial guess and/or a priori
Local view(1D atmosphere sufficient)Spectral range, resolution,noise “problem specific”Observations repeatable“Easy” verification & validationEverything known (almost)
Exoplanetsno climatologies!unknown constituents?atmos model �! init guess?Global view:disk-averaged spectrum“Sub-optimal” spec range,low resolution, high noiseA single observation?Validation ???Everything unknown
Remote Sensing Technology Institute WP1100 - Radiative Transfer 15
Exoplanets Retrievals — Workpackages
Set-up state vectorI Select parameters to retrieveI Appropriate discretization
Analyze conditioning, correlations, . . .Information content (weighting fct., PCA, SVD, . . . )Constraints
I Smoothness, positivity, . . .I “Physical” constraints
ImplementationI Derivative codeI Inverse problem solver
Earth-shine, Mars, Venus, Titan, . . . for verification & validationAnalyse exoplanet spectra(and observation, reduction, calibration . . . )
Remote Sensing Technology Institute WP1100 - Radiative Transfer 16
Temperature profiles of exoplanet atmospheres
calculatedstandard-atmospheres ofexoplanets orbitingdi↵erent stars;
my calculations arebased on the G-Star andM-Star due to theircontroversal lapse ratesabove 102[mb]
the points connected bythe straight lines definethe coarse (NZ=3)vertical temperatureprofile as given to theinput-file
Abbildung: Temperature profiles of exoplanetatmospheres [3]
Philipp Hochsta✏ Exoplanet Atmospheres
Remote Sensing Technology Institute WP1100 - Radiative Transfer 17
Correlationmatrix for G- and M-Star-Planet atmosphere
Correlationmatrix for atm. parameters of G-Star-Planet
Relate CO2 Tsurface Ttropopause Tstratopause H2O O3 pCO2 1.0000e+00 -1.54e-01 -4.32e-01 2.88e-02 1.04e-01 1.64e-02 -6.34e-01
Tsurface - 1.0000e+00 -1.46e-01 -5.06e-01 9.16e-01 -2.27e-01 5.58e-01Ttropopause - - 1.0000e+00 5.39e-01 -1.33e-01 -1.43e-02 1.20e-01Tstratopause - - - 1.0000e+00 -3.96e-01 8.93e-02 -3.00e-01
H2O - - - - 1.0000e+00 -2.39e-01 4.06e-01O3 - - - - - 1.0000e+00 4.41e-01
pressure - - - - - - 1.0000e+00
The table shows the correlation coe�cient K for each combination ofcolumns of the jacobian;
Correlationmatrix for atm. parameters of M-Star-Planets
Relate CO2 Tsurface Ttropopause Tstratopause H2O O3 pCO2 1.0000e+00 3.71e-01 -7.17e-01 -4.34e-01 -3.49e-01 -6.23e-02 3.14e-01
Tsurface - 1.0000e+00 -6.09e-01 -6.85e-01 -9.50e-01 8.01e-02 -4.58e-01Ttropopause - - 1.0000e+00 6.55e-01 4.55e-01 5.48e-02 -5.10e-02Tstratopause - - - 1.0000e+00 5.03e-01 -1.43e-01 4.71e-02
H2O - - - - 1.0000e+00 -8.9930e-02 4.92e-01O3 - - - - - 1.0000e+00 5.73e-01
pressure - - - - - - 1.0000e+00
Philipp Hochsta✏ Exoplanet Atmospheres
green cells indicate kKk � 0.5; G-planet ; M-planet
Remote Sensing Technology Institute WP1100 - Radiative Transfer 18
Summary
Looking back — forward modelingSQuIRRL �! GARLICfaster, more flexible, . . .SQuIRRL in Berlin:exoplanets (and young Earth)spectral signaturesSORTRA:I lbl with multiple scatteringI Validation: Venus SCIAI FGKM planets: clear + cloudy
Looking forward — inversionFeasibility:information content analysis! “optimized” state vectorConstraints:atmos. modeling ?Solver: Least squares ?
. . . and cloud studies . . .
Remote Sensing Technology Institute WP1100 - Radiative Transfer 19
Summary
Looking back — forward modelingSQuIRRL �! GARLICfaster, more flexible, . . .SQuIRRL in Berlin:exoplanets (and young Earth)spectral signaturesSORTRA:I lbl with multiple scatteringI Validation: Venus SCIAI FGKM planets: clear + cloudy
Looking forward — inversionFeasibility:information content analysis! “optimized” state vectorConstraints:atmos. modeling ?Solver: Least squares ?
. . . and cloud studies . . .
Remote Sensing Technology Institute WP1100 - Radiative Transfer 19
Where are we now . . . and where to go ?
Now: First StepsBerlin:Nonlinear least squares (LM)OP:Long expertise @ Earth
µWave – IR – UVFirst studies: correlation
Soon: Science and ToolsA Versatile Retrieval System
constrained least squares etc.forward model (incl. deriv):I molecules – lblI clouds – scatteringtransmission & emissionSWIR & TIR
CollaborationsWP1200 — 1D atmosphere modellingWP1300 — 3D atmosphere modelling(and retrieval @ MPS)
Remote Sensing Technology Institute WP1100 - Radiative Transfer 20
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