status of the lblrtm forward model for passive remote sensing · status of the lblrtm forward model...

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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

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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’?




• Consistency between species– TES: temperature from O3 and H2O consistent with CO2 ; N2O


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AIRS: new spectroscopyAtmosphere: sonde/adjusted ecmwf

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‘Truth’ isn’t ubiquitous- Yet!




• Consistency between species– TES: temperature from O3 and H2O consistent with CO2 ; AIRS: CO2 , N2O


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Back-up slides to follow………

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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

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a0

b1

a1

a2

Reference spectrum

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a0

b1

a2

a1

Reference spectrum

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Reference spectrum

a1

a0

a2

b1

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a0

b1

a2

a1

Reference spectrum

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a0

b1

a2

a1

Reference spectrum

30


a0

b1

a2

a1

Reference spectrum

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a0

b1

a2

a1

Reference spectrum

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Averaging Kernels

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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|)

status of the lblrtm forward model for passive remote sensing · status of the lblrtm forward model...

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