sentinel-3 olci: status - ioccg · 2013-12-20 · atm corr 865 20 vegetation, h 2o vap. ref. 885 10...

OLCI Status 26 Nov 2013 | ESRIN 1

Sentinel-3 OLCI: Status

Jens Nieke, F. Borde, C. Mavrocordatos


Outline

•  Background •  OLCI development status •  Assembly, Testing & Integration (AIT) •  Camera EM and FM test results •  OLCI core products •  Summary

Chl-a ENVISAT MERIS, 17-18 March 2011

L3 products: Belgian CHLa 90% Mar-Oct

2005-2010 (Ruddick)

ENVISAT MERIS Algae Bloom

(300m L1B RGB browse)


Sentinel-3 operations and acquisitions for each orbit


S3 OLCI: Technical details

Basic configuration similar to MERIS: •  5 Camera Optical Sub Assemblies (COSA),

•  5 Focal Plane Assemblies (FPA), •  5 Video Acquisition Modules (VAM),

•  1 Scrambling Window Assembly (SWA), •  1 OLCI Electronic Unit (OEU) managing all

the instrument functions, •  1 calibration assembly allowing radiometric

and spectral calibration.

Optical layout


OLCI Structure

OLCI structure: Camera bench (top), baseplate (bottom) and

VAM bench (vertical)

OLCI structure: side panels fit check


10:00 LST

C amera&1 C amera&2 C amera&3 C amera&4 C amera&5

Wes t55&deg_OZA

E as t

S S P14.1°

12.2°13.6°


Wes t55&deg_OZA

E as t

S S P14.1°

12.2°13.6°

~68.5° FoV

Across- track-tilt

Calibration Assembly

5 cameras Sentinel-3 OLCI Basic Geometry

1270 km

~09:00 LST ~10:30 LST


Transect showing MERIS sunglint MERIS band 9 (708 nm) Hawaii

0 20

40

60

80

100

120

140

160

180

200

-160 -158 -156 -154 -152 -150 -148 -146 longitude (deg) TO

A r

adia

nce

[mW

/(m

^2*

sr*n

m)]


Wes t55&deg_OZA

E as t

S S P14.1°

12.2°13.6°


Wes t55&deg_OZA

E as t

S S P14.1°

12.2°13.6°

Approximate position of OLCI cameras

(R. Doerffer)


Pushbroom Imaging Spectrometer (VIS-NIR) – similar to MERIS

Key Improvements/Features: !  More spectral bands (from 15 to 21): 400-1020

nm !  Broader swath: 1270 km !  Reduced sun glint by camera tilt in west direction

(12.20°) !  Absolute (relative) accuracy of 2% ( relative

0.5%) !  Polarisation sensitivity < 1% !  Full res. 300m acquired systematically for land &

ocean !  Reduced res. 1200m binned on ground (L1b) !  Improved characterization, e.g. straylight,

camera boundary characterization !  Ocean coverage < 4 days, (< 2 days, 2

satellites) !  Timeliness: 3 hours NRT Level 2 product !  100% overlap with SLSTR

OLCI: Ocean and Land Colour Instrument comparison to MERIS

MERIS Bands λ center Width Yellow substanace/detrital

pigments 412.5 10

Chl.. Abs. Max 442.5 10 Chl & other pigments 490 10

Susp. Sediments, red tide 510 10 Chl. Abs. Min 560 10

Suspended sediment 620 10 Chl. Abs, Chl. fluorescence 665 10

Chl. fluorescence peak 681.25 7.5 Chl. fluorescence ref., Atm.

Corr. 708.75 10

Vegetation, clouds 753.75 7.5 O2 R-branch abs. 761.25 2.5 O2 P-branch abs. 778.75 15

Atm corr 865 20 Vegetation, H2O vap. Ref. 885 10

H2O vap., Land 900 10 New OLCI bands λ center Width

Aerosol, in-water property 400 15 Fluorescence retrieval 673.75 7.5

Atmospheric parameter 764.375 3.75 Cloud top pressure 767.5 2.5

Atmos./aerosol correction 940 20 Atmos./aerosol correction 1020 40


Instrument CDR: Nov-2011. For the OLCI subsystems, all CDR are closed, EM tested and most of PFM HW is delivered:

- Camera Optical Sub-Assembly (COSA): all FM Cameras successfully delivered.

- Calibration Mechanism (CM): PFM with characterized FM diffusers delivered.

- Scrambling Window Assembly (SWA): SWU GSE and PFM delivered.

- Charge Coupled Devices (CCDs): all CCDs for S3A and S3B delivered.

- Video Acquisition Module (VAM) and Focal Plane Assembly (FPA): FPA PFM/

FM2/3/4/5 and VAM PFM and FM2 delivered and integrated in cameras.

- OLCI Electronics Unit (OEU): EM integrated in the OLCI EM instrument, PFM

delivery in preparation. - PFM Instrument Integration has started

S3A OLCI development status (Sep-2013)


Assembly, Testing and Integration (AIT) Sequence

Camera AIT (COSA+CCD+FPA)

Instrument AIT

•  AIT$for$5$cameras$completed$–  Camera$Integra5on$in$OLCI9A$

structure$started,$–  Calibra5on$mechanism$has$been$

characterised$and$delivered,$ready$for$integra5on,$

–  Instrument$delivery$to$satellite$level$planned$end$of$this$year.$

•  The$integra5on$of$5$cameras$in$the$PFM$instrument$has$started.$

FM3 camera during contrast test on CAAV2

bench.


OLCI Camera AIT

Camera under test

Camera mounted on the test bench (top) and with VAM (left)


Camera test & characterisation sequence


Characterized central wavelength for MERIS Camera 4.

•  Spectral)(theore-cal))linear)dispersion)model:)λ)=)1.25xl+C)

•  Devia-on)from)linear)model)is)characterised)for)central)column)")dispersion)law)model)

OLCI FM3 camera deviation from linear dispersion law

CCD row index

Mea

sure

- M

odel

(nm

)

-0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

0 100 200 300 400 500 600

Data FoV 0° 3rd order pol. model

OLCI Camera FM3 Spectral Sampling Interval SSI

-1.252 -1.250 -1.248 -1.246 -1.244 -1.242

0 100 200 300 400 500 600 CCD row index

SSI n

m

Spectral Dispersion

Same behavior as for MERIS


Spectral registration

-0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6

-400 -300 -200 -100 0 100 200 300 400

-0.4 -0.3 -0.2 Position in the camera FoV (pixels)

Δλ

(nm

)

Camera FM3 - Spectral Registration Δλ (l,k)

OL-DE-020: The spectral misregistration shall be less than 0.0014 um (goal: 0.001 um)

OLCI Results: •  FM#3 is compliant with goal, •  All cameras will have similar shape •  Preliminary Results on Instrument

level very promising

MERIS spectral registration after repairat reference wavelength 681nm

-0.6

-0.4

-0.2

0

0.2

0.4

0.60100200300400500600700800

Spatial pixel

Reg

istr

atio

n (n

m)

FM1FM2FM3FM4FM5

MERIS all cameras @ 681nm

Better Performance than for MERIS

FM#3: Δλ=0.5nm (681nm)

Preliminary results on instrument level: Max smile: 1.33nm @ 1020 nm


FWHM for Oa21 will not be 40nm but 23nm due to optical transmission and detector response. Note, SNR performance remains compliant with

large margins. (SNR EoL prediction: 197 vs Spec: 152)

SRD

CDR

(Pelloquin, C. and J. Nieke. 2012, OLCI and SLSTR simulated spectral response function, S3 Calval WS, Oct-2012)

Normalized Spectral Response Functions



Spatial (mis-)registration

OL-DE-160: The inter-channel spatial co-registration shall be less than 0.4 FR SSD in the spectral range from 400 to 900 nm (goal 0.3 FR SSD).

Measured ALT spatial registration at FoV center. Registration is very low: 6 arcsec at maximum, i.e.,

<0.1 SSD

OLCI Results: •  FM#3 is compliant with

goal, •  All cameras will have

similar shape, •  Preliminary Results on

Instrument level very promising.

FM#3: <0.1 SSD

MERIS ACT spatial registration after repair

350

450

550

650

750

850

950

1050-0.35-0.30-0.25-0.20-0.15-0.10-0.050.000.050.100.150.200.25

Registration (pixel)

Wav

elen

gth

(nm

) FM1FM2FM3FM4FM5

MERIS all cameras @ nadir

Better Performance than for MERIS

Instrument level Preliminary Results: Overall spatial mis-registration worse measured performance (in SSD)


During OLCI ground campaign (EM and FM2) Noise Spikes were detected. Most likely related to cosmic rays hitting the CCD. Next Steps: -  During Phase E1: Investigation on occurrence -  Mitigation via ground processing (TBD):

-  comparison of pixels with unexpected high levels with surrounding pixels, or

-  the comparison of these pixels with unexpected high levels with themselves in different temporal acquisitions.

Radiometric Performance: dark (1)

Camera EM tests

Camera FM2 + VAM FM2

MERIS noise spikes during SAA



Oscillation anomaly. •  Dark signal with frequency around

70KHz at the beginning (around 150pixels) of some micro-bands.

•  Phenomenon especially after dumping/binning many lines.

•  On FPA, CCD or VAM level no oscillations.

•  Impact: on radiometric stability and absolute accuracy for Oa13,14,15 and Oa19,20.

•  Investigations on all levels and

models (e.g., EGSE, grounding, EMC) ongoing.

•  Potential mitigation: –  Full characterisation (vacuum vs ambient) on

instrument level (TBC) –  Ground correction (for the stable portion of

the oscillation) (TBC)

Radiometric Performance: dark (2)

0 100 200 300 400 500 600 700 80038

38.5

39

39.5

40

40.5CAMERA output TVac [email protected]ºC Temporal Mean - G4

Pixel index

Tem

pora

l Mea

n (L

SB)

uBSM

uB44uB43uB42

G4

1.4LSBs

0 20 40 60 80 100 120

38.2

38.4

38.6

38.8

39

39.2

39.4

39.6

39.8

40

40.2

CAMERA output TVac [email protected]ºC Temporal Mean - G4

Pixel index

Tem

pora

l Mea

n (L

SB)

uBSM

uB44uB43uB42


FM3 camera + VAM FM2 SNR - RR

0

500

1000

1500

2000

2500

Oa1Oa2Oa3Oa4Oa5Oa6Oa7Oa8Oa9Oa10Oa11Oa12Oa13Oa14Oa15Oa16Oa17Oa18Oa19Oa20Oa21

Spectral channel

SN

R

OLCI RR measurement results: 5 x 5 measured samples vs. prediction (red)

Radiometric Performance: SNR MERIS SNR for different signal levels

Similar/better Performance than for MERIS

Note, SNR is difficult to measure and to compare directly with SRD Req. (dependence on signal level). Instrument test will provide confirmation.

OLCI Results: Measured RR SNR is close to predictions: •  Predicted SNR in flight. •  Requirement is met except marginally

for extreme blue channels.


Scatter Area

Illuminated Area

(Lmax)

60 pixel transition

Baffle

EM camera

SWU

Radiom. Performance: Straylight PFM camera Spatial NUST - µb35 - 520 nm

0.0001

0.001

0.01

0.1

1 0 200 400 600 800

Spatial pixel

Nor

mal

ised

ligh

t lev

el

Measurement Model

PFM camera Spatial NUST - µb19 - 775 nm

0.0001

0.001

0.01

0.1

1 0 200 400 600 800

Spatial pixel

Nor

mal

ised

ligh

t lev

el

Measurement

Model

PFM camera Spatial NUST - µb2 - 640 nm

0.0001

0.001

0.01

0.1

1 0 200 400 600 800

Spatial pixel

Nor

mal

ised

ligh

t lev

el

Measurement

Model

New spatial NUST set-up provides good results for the correlation with ASAP model

=> Baseline for efficient straylight correction!

Better Characterisation than for MERIS


Diffuser characterisation (1/2)

63

64

65

66

67

68

69

-40 -39 -38 -37 -36 -35 -34 -33 -32 -31 -30 -29 -28 -27 -26 -25 -24 -23 -22 -21 -20 -19 Azimuth (deg)

thet

a (d

eg)

Beginning of calibration

End of calibration

Characterised Sun incidences

21/01

21/12 21/10 21/09 21/08 21/07 21/06

21/05 21/04 21/02

21/11

21/03

Calibration window azimuth-zenith plot

(diffuser axes)

Diffuser BRDF !  BRDF measurements (relative and absolute) for FMA

and FMB for several set of wavelengths, incidence and observation angles covering the whole flight range.

!  Mathematical BRDF model were tested to fit the absolute measurements, but only 2 models (based on Rahman) gave good results.

!  Traceability to international standards by PTB/NPL. !  Final cross-validation between SLSTR and OLCI is

ongoing (2 NCRs still open).

Comparison Rahman/measurement

Accuracies in 1sigma


Diffuser characterisation (2/2) spectral calibration

3 absorption peaks are proposed for nominal spectral calibration

Erbium-doped Zenith 8%

« pink diffuser » 40 50 60 70 80 90

100

350 450 550 650 750 850 950 1050 1150 Wavelength (nm) R

efle

ctiv

ity (%

)

Peak @409 nm

40 50 60 70 80 90

100

400 404 408 412 416 420 Wavelength (nm)

Ref

lect

ivity

(%)

Peak @ 522 nm

30 40 50 60 70 80 90

100

515 520 525 530 535 Wavelength (nm)

Ref

lect

ivity

(%)

Peak @ 800 nm

30 40 50 60 70 80 90

100

790 795 800 805 810 Wavelength (nm)

Ref

lect

ivity

(%)

3 other peaks optional: 490 nm, 658 nm, 975 nm. MERIS absorption bands

Within OLCI a maximum of 3 peaks each with 15 spectral lines can be used.



Radiom. Performance: Polarization

•  Measurement performed on PFM camera

•  Improvements with respect to MERIS testing: 3 dichroic polarisers instead of 1

•  Characterisation of transmission uniformity for each polariser, main contributor to error budget Compliance

Channel FoV without SWU with SWU < 1% with SWU0° 0.81 0.2 OK +/- 0.337° 0.71 0.12 OK +/- 0.330° / / ? +/- 0.337° 0.23 / OK +/- 0.330° / / ? +/- 0.247° 0.31 / OK +/- 0.240° 0.48 / OK +/- 0.267° 0.77 0.34 OK +/- 0.260° 1.16 0.21 OK +/- 0.267° 0.94 0.14 OK +/- 0.260° 1.16 0.21 OK +/- 0.267° 1.01 0.16 OK +/- 0.260° 0.8 0.23 OK +/- 0.267° 0.8 0.17 OK +/- 0.26

Measurement accuracy (%)

Polarisation ratio PR (%)

Oa1

Oa2

Oa3

Oa5

Oa13

Oa18

Oa21



Conclusion

•  OLCI Development is built on MERIS heritage •  Maintain heritage:

–  Camera design, calibration principle, spectral bands

•  Provides Improvement: –  More spectral bands, 300m FR over land and ocean, NRT,

improved characterization…

•  OLCI A and B units are under development: a.  OLCI PFM delivered end of 2013,

b.  OLCI FM2 delivered Q3 2014.

•  OLCI camera test results and performance prediction demonstrate improved or similar performances as MERIS.

•  OLCI will secure the continuity of ocean and land colour observation for the next decade.


Acknowledgements

sentinel-3 olci: status - ioccg · 2013-12-20 · atm corr 865 20 vegetation, h 2o vap. ref. 885 10...

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