1st post launchSCIAMACHY calibration & Verification

MeetingL1b

Astrium Friedrichshafen – Germany24 July 2002

First Level 1b Spectral Calibration analysis

2

Level 1b Spectral Calibration analysis: content

The Spectral Calibration philosophy The Iecf Spectral Calibration Algorithm Related Verification Tasks: orbit behaviour Analysis specifics First results Other Spectral Calibration Verification Tasks Recommendations

3

The Spectral Calibration Philosophy

Objective: to assign a wavelength to each individual SCIA detector pixel during the flight.

Method: the relation between pixel index and wavelength is described by a 4th order polynomial:

To derive a set of calibration coefficients two calibration sources, the SLS and the sun, are analysed.

Stability: due to ageing of the instrument, the wavelength parameters needs to be updated on a regular basis. Iecf, Instrument Engineering and Calibration Facility, guarantees long term stability of scientific measurements.

44

33

2210 iiiii papapapaa

4

The Iecf Spectral Calibration Algorithm

Task: to determine coefficients of the 4th order polynomial for each channel as function of the orbital regions.

Input: Level 1b Newly Calculated Spectral ADS

Method: for each polynomial coefficient, given by the Spectral ADS as a function of orbital phase, a harmonic fit has to be performed in order to parameterise the orbital dependence.

The coefficients values are then computedfor a set of 12 fixed orbital phases:

  )_( ORSPcoeff

i ii iicoeffcoeff 2cos2sin)( 0

5

Related verification Task: orbit behaviour

L1.01.02: Number of orbital regions for spectral calibration

L1.09.03: Orbit region dependency

Due to the instrument’s thermal environment along the orbit, the spectral calibration can be expected to show orbital dependency. Therefore SLS measurements shall be executed along the entire orbit to investigate whether the number of measurements and the number of orbital regions are sufficient and the orbit phase boundaries are chosen properly.

6

Analysis specifics and overview

Level 1b product: SCI_NL__0PNPDK20020621_182502_000062172007_00056_01613_0129.N1

Orbits: 1613States: 10 SLS States (predefined State_ID 59), on 87 total States

Channel 1: variation long the orbit is close or less to 1/100 of a pixel

Channel 2: not analysed due to erroneous key-data set used by the Level 0 to 1b processor

Channels 3, 4, 5 and 6: variation long the orbit is close or less to 1/100 of a pixel

Channel 7 and 8: not analysed for no in-flight dark current correction of the the raw lamp spectrum

First Results: Orbit dependency for Channel 1

The algorithm performs correctly the harmonic fit of the coefficients.

… but is this the best approach to the Spectral Calibration?

-3.20E-05

-3.00E-05

-2.80E-05

-2.60E-05

-2.40E-05

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

Coeff

a1 [nm

]

ADS GADS

1.10E-10

1.20E-10

1.30E-10

1.40E-10

1.50E-10

1.60E-10

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

Coeff

a3 [nm

]

ADS GADS

5.00E-08

6.00E-08

7.00E-08

8.00E-08

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

Coeff

a2 [nm

]

ADS GADS

-1.46E-13

-1.44E-13

-1.42E-13

-1.40E-13

-1.38E-13

-1.36E-13

-1.34E-13

-1.32E-13

-1.30E-13

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

Coeff

a4 [nm

]

ADS GADS

Spectral Calibration - Channel 1

1.8E-02

1.9E-02

2.0E-02

2.1E-02

2.2E-02

2.3E-02

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

Coeff

a0 [nm

]ADS GADS

First Results: Orbit dependency for Channel 3

The algorithm performs correctly the harmonic fit of the coefficients.

… but is this the best approach to the Spectral Calibration?

Spectral Calibration - Channel 3

6.00E-02

6.04E-02

6.08E-02

6.12E-02

6.16E-02

6.20E-02

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a0 [nm

]ADS GADS

0.00E+00

1.00E-05

2.00E-05

3.00E-05

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a1 [nm

]

ADS GADS-5.50E-07

-5.10E-07

-4.70E-07

-4.30E-07

-3.90E-07

-3.50E-07

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a2 [nm

]

ADS GADS

1.00E-09

1.10E-09

1.20E-09

1.30E-09

1.40E-09

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a3 [nm

]

ADS GADS

-9.00E-13

-8.50E-13

-8.00E-13

-7.50E-13

-7.00E-13

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a4 [nm

]

ADS GADS

First Results: Orbit dependency for Channel 4

The algorithm performs correctly the harmonic fit of the coefficients.

… but is this the best approach to the Spectral Calibration?

Spectral Calibration - Channel 4

2.00E-02

2.20E-02

2.40E-02

2.60E-02

2.80E-02

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a0 [nm

]

ADS GADS

2.60E-04

2.70E-04

2.80E-04

2.90E-04

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a1 [nm

]

ADS GADS-1.60E-06

-1.58E-06

-1.56E-06

-1.54E-06

-1.52E-06

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a2 [nm

]

ADS GADS

2.67E-09

2.69E-09

2.71E-09

2.73E-09

2.75E-09

2.77E-09

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a3 [nm

]

ADS GADS

-1.42E-12

-1.41E-12

-1.40E-12

-1.39E-12

-1.38E-12

-1.37E-12

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a4 [nm

]

ADS GADS

First Results: Orbit dependency for Channel 5

The algorithm performs correctly the harmonic fit of the coefficients.

… but is this the best approach to the Spectral Calibration?

Spectral Calibration - Channel 5

1.65E-01

1.66E-01

1.67E-01

1.68E-01

1.69E-01

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a0 [nm

]

ADS GADS

1.50E-05

3.50E-05

5.50E-05

7.50E-05

9.50E-05

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a1 [nm

]

ADS GADS-1.38E-06

-1.34E-06

-1.30E-06

-1.26E-06

-1.22E-06

-1.18E-06

-1.14E-06

-1.10E-06

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a2 [nm

]

ADS GADS

2.10E-09

2.15E-09

2.20E-09

2.25E-09

2.30E-09

2.35E-09

2.40E-09

2.45E-09

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a3 [nm

]

ADS GADS

-1.30E-12

-1.25E-12

-1.20E-12

-1.15E-12

-1.10E-12

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a4 [nm

]

ADS GADS

First Results: Orbit dependency for Channel 6

The algorithm performs correctly the harmonic fit of the coefficients.

… but is this the best approach to the Spectral Calibration?

Spectral Calibration - Channel 6

1.20E-01

1.30E-01

1.40E-01

1.50E-01

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a0 [nm

]

ADS GADS

5.80E-05

7.80E-05

9.80E-05

1.18E-04

1.38E-04

1.58E-04

1.78E-04

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a1 [nm

]

ADS GADS-2.00E-06

-1.90E-06

-1.80E-06

-1.70E-06

-1.60E-06

-1.50E-06

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a2 [nm

]

ADS GADS

2.40E-09

2.50E-09

2.60E-09

2.70E-09

2.80E-09

2.90E-09

3.00E-09

3.10E-09

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a3 [nm

]

ADS GADS

-1.35E-12

-1.30E-12

-1.25E-12

-1.20E-12

-1.15E-12

-1.10E-12

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1Orbit phase

a4 [nm

]

ADS GADS

First Analysis: the harmonic fit approach for Channel 1

Orbit 1613

Maximum variation long the orbit: 1.1509E-03 nm or 0.01 of a pixel

-8.0E-04

-4.0E-04

0.0E+00

4.0E-04

8.0E-04

1.2E-03

1.6E-03

0 128 256 384 512 640 768 896 1024

Pixel ID

Diff

eren

ce in

Wvl

en [n

m]

Rec 2 Rec 6 Rec 7 Rec 8 Rec 9 Rec 10 Rec 11 Rec 12

Channel 1: Pixel 950

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

Channel 1: Pixel 325

-0.003

-0.0025

-0.002

-0.0015

-0.001

-0.0005

0

0.0005

0.001

0.0015

0.002

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

First Analysis: the harmonic fit approach for Channel 3

Orbit 1613

Maximum variation long the orbit: 2.1606E-02 nm or 0.090 of a pixel

-2.4E-02

-1.6E-02

-8.0E-03

0.0E+00

8.0E-03

1.6E-02

2.4E-02

0 128 256 384 512 640 768 896 1024

Pixel ID

Diff

eren

ce in W

vlen

[nm

]

Rec 2 Rec 6 Rec 7 Rec 8 Rec 9 Rec 10 Rec 11 Rec 12

Channel 3: pixel 950

-0.035

-0.03

-0.025

-0.02

-0.015

-0.01

-0.005

0

0.005

0.01

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

Channel 3: pixel 300

-0.035

-0.03

-0.025

-0.02

-0.015

-0.01

-0.005

0

0.005

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

First Analysis: the harmonic fit approach for Channel 4

Orbit 1613

Maximum variation long the orbit: 1.5229E-03 nm or 0.007 of a pixel

-2.0E-03

-1.6E-03

-1.2E-03

-8.0E-04

-4.0E-04

0.0E+00

4.0E-04

8.0E-04

1.2E-03

1.6E-03

0 128 256 384 512 640 768 896 1024Pixel ID

Diff

eren

ce in

Wvl

en [n

m]

Rec 2 Rec 6 Rec 7 Rec 8 Rec 9 Rec 10 Rec 11 Rec 12

Channel 4: pixel 950

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.004

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

Channel 4: pixel 340

-0.003

-0.002

-0.001

0

0.001

0.002

0.003

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

First Analysis: the harmonic fit approach for Channel 5

Orbit 1613

Maximum variation long the orbit: 2.0408E-02 nm or 0.07 of a pixel

-1.6E-02-1.2E-02-8.0E-03-4.0E-030.0E+004.0E-038.0E-031.2E-021.6E-022.0E-022.4E-02

0 128 256 384 512 640 768 896 1024Pixel ID

Diff

eren

ce in

Wvl

en [n

m]

Rec 2 Rec 6 Rec 7 Rec 8 Rec 9 Rec 10 Rec 11 Rec 12

Channel 5: pixel 950

-0.015

-0.01

-0.005

0

0.005

0.01

0.015

0.02

0.025

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

Channel 5: pixel 340

-0.015

-0.01

-0.005

0

0.005

0.01

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

First Analysis: the harmonic fit approach for Channel 6

Orbit 1613

Maximum variation long the orbit: 3.2390E-02nm or 0.041 of a pixel

-2.0E-02

-1.0E-02

0.0E+00

1.0E-02

2.0E-02

3.0E-02

4.0E-02

0 128 256 384 512 640 768 896 1024Pixel ID

Diff

eren

ce in W

vlen

[nm

]

Rec 2 Rec 6 Rec 7 Rec 8 Rec 9 Rec 10 Rec 11 Rec 12

Channel 6: pixel 950

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

Channel 6: pixel 330

-0.03

-0.025

-0.02

-0.015

-0.01

-0.005

0

0.005

0.01

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Orbit Phase

Diff

eren

ce in

Wvl

en [n

m]

First analysis: variation on the input for Channel 1

Coefficient average long the orbit as reference

Maximum variation long the orbit from average: 1.5786E-03 nm or 0.013 of a pixel

-1.50E-03

-1.00E-03

-5.00E-04

0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

0 128 256 384 512 640 768 896 1024Pixel ID

Diff

eren

ce in

Wvl

en [n

m]

Rec 1 Rec 2 Rec 3 Rec 4 Rec 5 Rec 6 Rec 7 Rec 8

Maximum variation long the orbit from fit: 1.1509E-03 nm or 0.01 of a pixel

First analysis: variation on the input for Channel 3

Coefficient average long the orbit as reference

-3.00E-03

-2.00E-03

-1.00E-03

0.00E+00

1.00E-03

2.00E-03

3.00E-03

0 128 256 384 512 640 768 896 1024Pixel ID

Diff

eren

ce in

Wvl

en [n

m]

Rec 1 Rec 2 Rec 3 Rec 4 Rec 5 Rec 6 Rec 7 Rec 8

Maximum variation long the orbit from average: 2.2911E-03 nm or 0.010 of a pixel

Maximum variation long the orbit from fit: 2.1606E-02 nm or 0.090 of a pixel

First analysis: variation on the input for Channel 4

Coefficient average long the orbit as reference

Maximum variation long the orbit from average: 1.8100E-03 nm or 0.008 of a pixel

Maximum variation long the orbit from fit: 1.5229E-03 nm or 0.007 of a pixel

-2.00E-03

-1.50E-03

-1.00E-03

-5.00E-04

0.00E+00

5.00E-04

1.00E-03

1.50E-03

2.00E-03

0 128 256 384 512 640 768 896 1024

Pixel ID

Diff

eren

ce in

Wvl

en [n

m]

Rec 1 Rec 2 Rec 3 Rec 4 Rec 5 Rec 6 Rec 7 Rec 8

First analysis: variation on the input for Channel 5

Coefficient average long the orbit as reference

Maximum variation long the orbit from average: 3.2879E-03 nm or 0.012 of a pixel

Maximum variation long the orbit: 2.0408E-02 nm or 0.07 of a pixel

-0.0040

-0.0030

-0.0020

-0.0010

0.0000

0.0010

0.0020

0.0030

0 128 256 384 512 640 768 896 1024

Pixel ID

Diff

eren

ce in

Wvl

en [n

m]

Rec 1 Rec 2 Rec 3 Rec 4 Rec 5 Rec 6 Rec 7 Rec 8

First analysis: variation on the input for Channel 6

Coefficient average long the orbit as reference

Maximum variation long the orbit from average: 4.2989E-03 nm or 0.006 of a pixel

Maximum variation long the orbit: 3.2390E-02nm or 0.041 of a pixel

-6.00E-03

-4.00E-03

-2.00E-03

0.00E+00

2.00E-03

4.00E-03

6.00E-03

0 128 256 384 512 640 768 896 1024

Pixel ID

Diff

eren

ce in

Wvl

en [n

m]

Rec 1 Rec 2 Rec 3 Rec 4 Rec 5 Rec 6 Rec 7 Rec 8

22

First Analysis: Summary

Level 1b: variation long the

orbit [nm]

Iecf output: variation long

the orbit [nm] Minumum variation

Ch 1 1.5786E-03 1.1509E-03 Iecf output

Ch 3 -2.7120E-03 -2.1606E-02 Average Level 1b

Ch 4 1.8100E-03 -1.5229E-03 Iecf output

Ch 5 -3.2879E-03 2.0408E-02 Average Level 1b

Ch 6 -4.9289E-03 3.2390E-02 Average Level 1b

Reference average coeffs

Level 1b: variation long the

orbit [pixel]

Iecf output: variation long

the orbit [pixel] Pixel spacing

Ch 1 0.0133 0.0097 1.1901E-01

Ch 3 0.0113 0.0904 2.3902E-01

Ch 4 0.0085 0.0072 2.1192E-01

Ch 5 0.0116 0.0722 2.8276E-01

Ch 6 0.0063 0.0414 7.8224E-01

Reference average coeffs Ref. corresponding Level 1b

Ref. corresponding Level 1b

23

All Spectral Cal Related Verification Tasks

L1.01.02 Number of orbital regions for spectral calibration

• L1.02.03 Wavelength calibration - selected line list not changes

• L1.02.04 Slit function parameters unchanged

• L1.09.01 Verification of precise basis for spectral calibration

• L1.09.02 Verification of selected lines for calibration L1.09.03 Verify orbit region dependency

• L1.09.04 Verify whether SLS or Fraunhofer calibration shall be the baseline

L1.14.01: Wavelength calibration differences monitoring

24

Level 1b Spectral Calibration analysis: Recommendations

The approach averaging the coefficients from the Level 1b seems to give better results

Fit based on a lower order polynomial shall be investigated …