Cross-­‐track  Infrared  Sounder  (CrIS):    Radiometric  Calibra:on  and  Valida:on  

 David  Tobin,  Hank  Revercomb,  Joe  Taylor,  Robert  Knuteson,  Greg  Quinn,  Dan  DeSlover,  Lori  Borg,  Graeme  Mar:n,  Aronne  Merrilli,  Tom  Greenwald  

 AMS  

7  Jan  2014      

Outline  •  Suomi-­‐NPP  CrIS  

–  Radiometric  Calibra5on  Uncertainty  –  Satellite  Intercalibra5on  results  –  Aircra;  Underflights  –  Calibra5on  algorithm/parameter  inves5ga5ons  

•  Recent  JPSS-­‐1  CrIS  TVAC  results  

Ø Overall  emphasis  on    –  Consistency  among  FOVs,  spectral  regions,  signal  levels  –  Absolute  accuracy,  reproducibility,  traceability  

2  

3  

Acknowledgements:    

NOAA  CrIS  SDR  Project/Team  –  Yong  Han,  Denis  Tremblay  NOAA  JPSS  CalVal/RR  Project  –  Mitch  Goldberg  

NASA  JPSS  Flight  Project  –  Jim  Gleason,  David  Johnson  NASA  Satellite  Calibra5on  Interconsistency  Studies  –  Lucia  Tsaoussi  

 Exelis  –  Lawrence  Suwinski,  Steve  Wells,  et  al.  Atmosphere  PEATE  at  UW  –  Liam  Gumley  et  al.  

 

AIRS Atmospheric InfraRed Sounder Grating spectrometer 166 kg, 256 W 13.5 km FOV at nadir, contiguous Launched on NASA Aqua in 2002

IASI Infrared Atmospheric Sounding Interferometer

Michelson interferometer 236 kg, 210 W

2x2 12 km FOVs at nadir, non-contiguous Launched on Metop-A in 2006

CrIS Cross-track Infrared Sounder Michelson interferometer 146 kg, 110 W 3x3 14 km FOVs at nadir, contiguous Launched on Suomi NPP, 28 Oct 2011

Full scale model at 2010 IASI meeting

4

600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800

AIRS: 2002-

IASI: 2006-

Spectral Coverage and Resolution Comparison

CrIS: 2011-

CrIS: Full Resolution 4 Dec 2014 -

±0.8 cm OPD unapodized 9 FOV/50 km square

±0.8, 0.4, 0.2 cm OPD unapodized 9 FOV/50km square

L1C:±2 cm OPD Gausian apodized 4 FOV/50km square

L1B: > 1200 Resolving Power 9 FOV/50km square

5

wavenumber  

Suomi-­‐NPP  CrIS  Radiometric  Uncertainty  Es:mate  

Simplified  On-­‐Orbit  Radiometric  Calibra:on  Equa:on:  

     REarth  =  Re  {(C’Earth  –  C’Space)  /(C’ICT-­‐C’Space)}  RICT      with:    

Nonlinearity  Correc5on:    C’  =  C  �  (1  +  2  a2  VDC)  ICT  Predicted  Radiance:    RICT  =  εICT  B(TICT)  +  (1-­‐εICT)  [  0.5  B(TICT,  Refl,  Measured)  +  0.5  B(TICT,  Refl,  Modeled)]  

   

   Parameter  Uncertain:es:  Parameter   Nominal  Values   3-­‐σ  Uncertainty  

TICT   280K   112.5  mK  

εICT   0.974-­‐0.996   0.03  

TICT,  Refl,  Measured   280K   1.5  K  

TICT,  Refl,  Modeled   280K   3  K  

a2  LW  band     0.01  –  0.03  V-­‐1   0.00403  V-­‐1  

a2  MW  band   0.001  –  0.12  V-­‐1   0.00128  –  0.00168  V-­‐1  

6  

(Differen5al  error  analysis  of  the  calibra5on  equa5on,  aimed  at  providing  a  useful  es5mate  of  the  absolute  accuracy  of  the  mean  of  a  large  ensemble  of  observa5ons.    Input  parameter  uncertain5es  are  based  on  the  design  of  the  sensor  and  engineering  es5mates  of  the  calibra5on  parameters;  i.e.  no  external  informa5on  via  external  “Cal/Val”  used.)  

200

220

240

260

280

300

BT (K

)

700 800 900 1000

−0.2

−0.1

0

0.1

0.2

0.3

wavenumber

3−si

gma

RU

(K)

200 220 240 260 280 3000

0.1

0.2

0.3

BT (K)

3−si

gma

RU

(K)

wavenumber700 800 900 1000

1200 1300 1400 1500 1600 1700wavenumber

200 220 240 260 280 300BT (K)

wavenumber1300 1400 1500 1600 1700

2200 2300 2400 2500wavenumber

200 220 240 260 280 300BT (K)

wavenumber2200 2300 2400 2500

Example 3-sigma RU estimates

For a typical warm, ~clear sky spectrum

200

220

240

260

280

300

BT (K

)

700 800 900 1000

−0.2

−0.1

0

0.1

0.2

0.3

wavenumber

3−si

gma

RU

(K)

200 220 240 260 280 3000

0.1

0.2

0.3

BT (K)

3−si

gma

RU

(K)

wavenumber700 800 900 1000

1200 1300 1400 1500 1600 1700wavenumber

200 220 240 260 280 300BT (K)

wavenumber1300 1400 1500 1600 1700

2200 2300 2400 2500wavenumber

200 220 240 260 280 300BT (K)

wavenumber2200 2300 2400 2500

7  

500 1000 1500 2000 25000

0.05

0.1

0.15

0.2

wavenumber (cm−1)

3m B

T R

U (K

)

TICT¡ICTTICT,Refl,MeasTICT,Refl,ModelTST¡STTST,Refla2Total RU

500 1000 1500 2000 25000

0.05

0.1

0.15

0.2

wavenumber (cm−1)

3m B

T R

U (K

)

TICT¡ICTTICT,Refl,MeasTICT,Refl,ModelTST¡STTST,Refla2Total RU

BT (K)

3−si

gma

RU

(K)

200 250 3000

0.1

0.2

0.3

0.4

0.5

BT (K)

200 250 300

log(count)0 5 10

BT (K)200 250 300

Example 3-sigma RU estimates

LW MW SW

Log scale RU distributions for one orbit of CrIS Earth view data, including all FOVs and spectral channels within the band:

8  

Ø  Uncertain5es  are  greatly  reduced  due  to  re-­‐analysis  of  the  TVAC  data  and  on-­‐orbit  FOV-­‐2-­‐FOV  analysis.    In  par5cular,  MW  band  uncertain5es  are  greatly  reduced  due  to  the  high  degree  of  linearity  of  MW  reference  FOV9.  

Ø  Overall,  RU  is  <0.3K  (LW),  <0.15K  (MW),  <0.15K  (SW):  Beser  than  spec  by  approximately  a  factor  of  4.  

Inter-­‐comparison  studies;  AIRS/IASI/CrIS  Simultaneous  Nadir  Overpasses  

9  

Trends  (mK/Decade):  

 -­‐8  ±  5        

42  ±  13          

10  ±  7  

SNO  differences  versus  scene  BT  

11  

•  ~50  mK  agreement  at  280K  •  At  the  cold  end,  mean  differences  range  from  0.1  to  0.3K    

BT (K)190200210220230240250260270280290

BT D

iff (K

)

-0.1

0

0.1

0.2

0.3

0.4

0.5AIRS - IASI-AAIRS - IASI-BCrIS - IASI-ACrIS - IASI-B

Mean  SNO  differences  for  910-­‐930  cm-­‐1.    Error-­‐bars  represent  sta5s5cal  SNO  matchup  uncertainty,  not  sensors  RU.      

May  15  Underflight  example:  S-­‐HIS  and  CrIS  895–900  cm-­‐1  BTs  overlaid  on  VIIRS  true  color  image  

May  2013  Suomi-­‐NPP  JPSS  Aircrab  Campaign  Scanning-­‐HIS  evalua:ons  of  CrIS  Calibra:on  

12  

BT  [K]  

BT  [K]  

13  

NIST  TXR  Valida5on  of  S-­‐HIS  Radiances  •  Pre-­‐integra5on  calibra5on  of  on-­‐board  blackbody  references  at  subsystem  level    

•  Pre  and  post  deployment  end-­‐to-­‐end  calibra5on  verifica5on    

•  Instrument  calibra5on  during  flight  using  two  on-­‐board  calibra5on  blackbodies  

•  Periodic  end-­‐to-­‐end  radiance  evalua5ons  under  flight  like  condi5ons  with  NIST  transfer  sensors.    

Post  Mission  End-­‐to-­‐End  Calibra5on  Verifica5on  

Scanning-­‐HIS  Calibra:on,  Calibra:on  Verifica:on,  and  Traceability  

14  

Calibra:on  Verifica:on  Results:  Double  Obs  Minus  Calc  (DOMC)  Methodology,    on  CrIS  spectral  scale  and  resolu:on  with  Hamming  apodiza:on  

CrIS  LW   CrIS  MW   CrIS  SW  

CrIS/S-­‐HIS  Underflight  Results  

Mean  DOMC    ±  uncertainty  CrIS  RU  

March  2015  Suomi-­‐NPP  JPSS  Aircrab  Campaign  

15  

−80 −70 −60 −50 −40 −30 −20 −10 0

60

65

70

75

80

85NPP nadir tracks, 07−Mar−2015

04:26

04:27

04:28

04:29

04:30

06:06

06:07

06:08

06:09

06:10

06:11

06:12

07:47

07:48

07:49

07:50

07:51

07:52

07:53

09:2911:06

12:43

12:44

12:45

12:46

12:47

12:48

14:23

14:24

14:25

14:26

14:27

14:28

14:29

16:04

16:05

16:06

16:07

16:08

16:09

17:46

−80 −70 −60 −50 −40 −30 −20 −10 0

60

65

70

75

80

85METOP−A nadir tracks, 07−Mar−2015

00:51

00:52

00:53

00:54

00:55

11:15

11:16

11:17

12:53

12:54

12:55

12:56

12:57

12:58

14:33

14:34

14:35

14:36

14:37

14:38

14:39

14:40

16:15

16:16

16:17

16:18

17:56

19:33

19:34

21:09

21:10

21:11

21:12

21:13

21:14

21:15

22:50

22:51

22:52

22:53

22:54

22:55

22:56

−80 −70 −60 −50 −40 −30 −20 −10 0

60

65

70

75

80

85METOP−B nadir tracks, 07−Mar−2015

00:00

00:00

00:01

00:02

00:03

01:39

01:40

12:01

12:02

12:03

12:04

12:05

13:40

13:41

13:42

13:43

13:44

13:45

13:46

15:21

15:22

15:23

15:24

15:25

15:26

15:27

15:28

17:03

17:04

18:40

20:19

20:20

20:21

20:22

21:57

21:58

21:59

22:00

22:01

22:02

22:03

23:38

23:39

23:40

23:41

23:42

23:43

−80 −70 −60 −50 −40 −30 −20 −10 0

60

65

70

75

80

85Aqua nadir tracks, 07−Mar−2015

03:14

03:15

03:16

04:49

04:50

04:51

04:52

04:53

04:54

04:55

06:27

06:28

06:29

06:30

06:31

06:32

06:33

08:06

08:07

08:08

08:09

08:10

09:45 11:20

12:54

12:55

12:56

12:57

12:58

12:59

14:32

14:33

14:34

14:35

14:36

14:37

14:38

16:11

16:12

16:13

16:14

16:15

17:49

17:50

•  S-­‐HIS,  NAST-­‐I,  NAST-­‐M,  and  MASTER  on  the  NASA  ER-­‐2  

•  Opera:ons  out  of  Keflavik,  Iceland  with  satellite  underflights  over  Greenland  

•  Coordina:on  with  the  Summit  Camp  ground  site  

Objec:ves:  1.   Cold  scene  calibra:on  evalua:on  2.   Cold  scene  sounding  performance  

evalua:on    

On-going Suomi-NPP CrIS calibration algorithm/parameter investigations

•  Scene  mirror  induced  polariza5on  •  Possible  low  level  SW  band  Nonlinearity  •  Spectral  Ringing  ar5facts  in  unapodized  spectra  

•  FIR  filter  induced  ar5facts  •  “True”  Ringing  

16  

0 10 20 30 40 50 60 70 80 90−0.1

−0.05

0

0.05

0.1

CrIS cross track scan index

VIIR

S −

CrIS

(K)

200−210 K210−220 K220−230 K230−240 K240−250 K250−260 K260−270 K270−280 K280−290 K290−300 K300−310 K310−320 K320−330 K

Error  from  Scene  Mirror  Induced  Polariza:on  •  CrIS  uses  a  45°  gold  scene  mirror  that  provides  low  sensi5vity  to  polariza5on;  no  

correc5on  is  included  in  the  SDR  algorithm/processing.  •  However,  it  seems  almost  certain  that  CrIS  should  have  polariza5on  effects  of  ~0.1  K  for  

especially  warm  and  cold  brightness  temperatures  in  some  spectral  regions.  •  A  correc5on  should  be  developed  based  on  CrIS  characteriza5on  tests  yet  to  be  

conducted  (measurements  of  scene  mirror  degree  of  polariza5on,  pr,  and  interferometer  polariza5on  sensi5vity,  pt)  

•  Radiance  error  dependence  ~2prpt  (N  –  BICT)  •  Sugges5ons  of  this  type  of  behavior  in  CrIS/VIIRS  comparisons  vs.  scan  angle:  

17  *  Biases  removed  for  mean  of  INDICES  1-­‐10  &  80-­‐90  

Scan  Angle  and  Scene  BT  dependence  of  VIIRS/CrIS  Comparisons  at  10.8µm*  

18  

200

250

300

BT (K

)

200

250

300

BT (K

)

2150 2200 2250 2300 2350 2400 2450 2500 25500

0.05

0.1

wavenumber

BT (K

)

SW  Band  Biases  •  FOV-­‐2-­‐FOV  analyses  and  differences  with  

respect  to  other  sensors  suggest  small  ar5facts  in  the  SW  band,  both  in  Mean  biases  and  FOV-­‐2-­‐FOV  differences.        E.g.  Differences  with  respect  to  IASI    

•  Mechanisms  inves5gated  to  date:  –  Spectral  shi;  –  Thermal  SP  view  contamina5on  –  Solar  SP  view  contamina5on  –  Noise  –  Polariza5on  Ø  Low  level  Nonlinearity  

•  Displays  FOV  dependent  behavior  •  Has  plausible  spectral  and  scene  level  

dependencies    

0.20

0.20.40.60.8

FOV 1

−0.20

0.20.40.60.8

FOV 2

−0.20

0.20.40.60.8

FOV 3

0.20

0.20.40.60.8

FOV 4

−0.20

0.20.40.60.8

FOV 5

−0.20

0.20.40.60.8

FOV 6

22002300240025000.2

00.20.40.60.8

FOV 7

2200230024002500−0.2

00.20.40.60.8

FOV 8

2200230024002500−0.2

00.20.40.60.8

FOV 9

CrIS-­‐IA

SI  (K

)  CrIS-­‐IA

SI  (K

)  CrIS-­‐IA

SI  (K

)  

wavenumber   wavenumber   wavenumber  

                 Mean  for  all  FOVs                    Difference  for  this  FOV  

Sample  spectra  (top)  and  Effect  of  small  NLC  (bosom)  

Fore  op:cs   IFM  

On-­‐orbit  CrIS  Signal  Processing:    CrIS  uses  FIR  filtering  and  decima:on  of  the  original  highly  sampled  interferogram  

to  select  the  spectral  region  of  interest  and  decrease  downlink  volume  

ab  op:cs  &  

filters  

Detector  Earth  Scene   LPF  

preamp   A/D  FIR  BPF  

Decimate  

Decimated  Interferogram  

Truncate  

Responsivity  FIR  filter  

Band  edges  

FIR  filter  in  Time  and  Spectral  domains  

Ø  Non-­‐cyclical  :me-­‐domain  applica:on  of  the  FIR  filter  violates  the  Convolu:on  Theorem  19  

Interferometer  Sweep  Direc:on  Differences  

645 650 655 660 665 670 675 680−1

−0.5

0

0.5

1

wavenumber

BT D

iff (K

)

old processing

FOV 5Side FOVsCorner FOVs

645 650 655 660 665 670 675 680−1

−0.5

0

0.5

1

wavenumberBT

Diff

(K)

new processing

FOV 5Side FOVsCorner FOVs

20  

Current  processing   New  prototype  processing  

Interferometer  Sweep  Direc:on  Differences  

ß  Cross  track  à   ß  Cross  track  à   ß  Cross  track  à  

ß  Along  track  à  

BT  (K)   BT  Diff  (K)   BT  Diff  (K)  

LW  window  BT   Current  processing   New  prototype  processing  

Difference  between  even  and  odd  index  spectral  channels  within  648-­‐660  cm-­‐1  

21  

JPSS-­‐1  CrIS  Thermal  Vacuum  Test  Results  

22  

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80

0.5

−5

0

5

FOV 1FOV 2FOV 3FOV 4FOV 5FOV 6FOV 7FOV 8FOV 9

0 0.2 0.4 0.6 0.8 10

0.5

1

ECT@200K  

ECT@233K  

ECT@260K  

ECT@287K  

ECT@299K  

ECT@310K  JPSS-­‐1  CRIS  Brightness  Temperature  Residuals  before  Non-­‐linearity  Analysis  

23

ECT@200K  

ECT@233K  

ECT@260K  

ECT@287K  

ECT@299K  

ECT@310K  JPSS-­‐1  CRIS  Brightness  Temperature  Residuals  aber  Non-­‐linearity  Analysis  

24

25  

1 2 3 4 5 6 7 8 90

0.01

0.02

0.03

0.04

a2 (V

−1)

FOV #

Longwave

S−NPPJPSS−1

1 2 3 4 5 6 7 8 90

0.02

0.04

0.06

0.08

0.1

a2 (V

−1)

FOV #

Midwave

S−NPPJPSS−1

Comparison  of  S-­‐NPP  and  JPSS-­‐1  Radiometric  Nonlinearity  coefficients  

JPSS-­‐1  CrIS  TVAC  Gas  Cell  Transmission  spectra  All  FOVs  (center,  sides,  corners),  before  Self-­‐Apodiza:on  correc:ons  

CO2  

NH3  

CH4  

CO  

26

JPSS-­‐1  CrIS  TVAC  Gas  Cell  Transmission  spectra  All  FOVs  (center,  sides,  corners),  aber  Self-­‐Apodiza:on  correc:ons  

CO2  

NH3  

CH4  

CO  

27

28  

The  End    

Thank  you