iasi fm2 on metop a performances after 1.5 year in...

ITSC-16, Angra dos Reis, 7-13 May 2008 D.Blumstein CNES DCT/PO/EV

IASI FM2 on METOP APerformances after 1.5 year in orbit

International TOVS Study Conference 167–13, May 2008

Angra dos Reis, Brazil

D. Blumstein1, E.Pequignot1, B.Tournier2, R.Fjortoft1, L.Buffet1, C.Larigauderie1,T.Phulpin1, I.Gaudel1 and the IASI TEC Team

(1) Centre National d'Etudes Spatiales (CNES), Toulouse, France(2) NOVELTIS, Toulouse, France

2D.Blumstein DCT/PO/EVITSC-16, Angra dos Reis, 7-13 May 2008

Outline

■ First decontamination

■ Stability of the instrument

■ Spectra rejectionsDay 2 improvements of processing

■ Intercalibration IASI / AIRS

see IASI performances assessment at the 1st IASI Conference•

http://smsc.cnes.fr/IASI


Evolution of contamination effect (ice) 2007-2008IASI FM2 Instrument Noise (pixel 1)

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650 850 1050 1250 1450 1650 1850Wave Number (cm-1)

NeD

T at

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)

Spec Dec 2006

IASI FM2 Instrument Noise (pixel 1)

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Spec Dec 2006 Apr 2007


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)

Spec Dec 2006 Apr 2007 Sept 2007


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650 850 1050 1250 1450 1650 1850Wave Number (cm-1)

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Spec Dec 2006 Apr 2007 Sept 2007 Feb 2008


After first IASI decontamination

■First IASI decontamination end of March 2008 (1.5 year after launch)


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Dec 2006 Spec end of March 2008


Evolution of the measured transmission loss

Smoothed and debiased ratios

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Rat

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ficie

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First IASI decontaminationend of March 2008 (1.5 year after launch)

■

Successulrecovery of the initial radiometric noise IASI•

Initially

measured

beginning

of

December

2006

Evolution of maximum loss of transmision (at 850 cm-1)

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Date

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Contamination rateNow 1/4 of the initial rateNo need for new deconta-mination before 2 years

850 cm-1


Fixed Cube Corner Offset

■Accurate determination

Std < 0.2 µm

■Stability over 16 months

Small drift 1 µm

■Period of analysis

4th Dec 200631th Mar 2008

Fixed Cube Corner Offset

-21

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500 1500 2500 3500 4500 5500 6500 7500Orbit Number

Offs

et (µ

m)

Y0 CD0 Z0 CD0 Y0 CD1 Z0 CD1


Interferometric Axis Position

■Stability over 12 monthsNegligible drift Results provided at Angletconference confirmed•

Obtained at that time from 5.5 months of data

■Period of analysis16 th Apr 20071 th Mar 2008

■Small evolution 11 July 2007Cause by parameter updating (spectral database)Amplitude 30 µradEquivalent to Δν/ν = 5 10-7

11 July 2007Parameter updating


Long term evolution of other parameters

Temperatures

Optical Bench Black Body

Geometry IASI / AVHRR1 A

VH

RR

Pix

el (~

1km

)

■Long term evolution over 1 year1 point per orbitaverage over 1 orbit

■Period of analysis16 th Apr 20071 th Apr 2008

■Reminder : orbital stability verified during Cal/Val

0.1

K

5 K


Regulation margin of the detectors temperatureCBS power regulation (mW)

observation of 2 orbits every 2 months

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30/11/2006 29/01/2007 30/03/2007 29/05/2007 28/07/2007 26/09/2007 25/11/2007 24/01/2008 24/03/2008

pow

er (m

W)

■Stable on the long termSmall seasonal effect, small orbital variation

■Very good indicator that the temperature of the detectors will be kept lowStrong impact on the radiometric noise for long wavelength


Fraction of Spectra rejected by on-board processing

End of Cal/Val


Fraction of Spectra rejected by on-ground processing


Spectra affected by Spikes

Histogramme of the number of spikes per box 50 x 50 km2affected by at least 1 spike

82.17%

15.75%

1.92% 0.16%0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

1 2 3 4

Histogram of the number of spikes per scan

1.282%

0.246%

0.030% 0.003%0.0%

0.2%

0.4%

0.6%

0.8%

1.0%

1.2%

1.4%

1 2 3 4

■

98.5 % of earth views (groups of 4 soundings) not affected by spikes

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Among the 1.5 % of earth views affected by spikes

E.g. over the South Atlantic Anomaly (SAA) 82.2 % have more than 3 spectra available97.9 % have more than 2 spectra available99.8 % have more than 1 spectrum

■

If the 4 IASI pixels of each Earth View are not assimilated

Dynamic selection of the selected soundingincrease availability of the measurements

■

On the long termProposal for Day 2 evolution of IASI processing


Spectra not computed because of NZPD error

■Small fraction of spectra not available because not computed by on-board processing

Between 0.15 % (Pixel 1&4) and 0.3 % (Pixel 2)Stable over 9 months

■Geographic repartition1 or 2 occurrences max per month per bin of 0.5 x 0.5 deg2

Feb 2008Dec 2007


Spectra not computed because of NZPD error

■Brightness Temperatures from the IIS imagerBlack curve : Histogram of BT in the vicinity of rejected spectra •

1/4 of the IIS imageRed curve : Histogram of BT in the IASI footprint for rejected spectra

■ConclusionAffected pixels : 0.3 %Histogram of rejected pixels

FWHM = 25 KClose shape of the 2 histograms


Proposed evolutions of IASI processing for the day 2

■ Add more detailed information for the cause of rejected spectraSpike reason, NZPD reason, OverFlows, Other

■ In case of a spike occurrence, provide B1 and B2 spectra when availableWith proper flagging

■ Add AVHRR L1B cloud mask information in the L1C product

■ Add IIS image Brightness Temperature average and variance in L1C prodFor easy spatially uniform scenes detection

■ Add minor modifications for improving (or easing) the monitoring of IASI performance by the TEC

No impact on the L1C products


Intercalibration IASI-AIRS (GSICS)

■Method : for intercomparison at high spectral resolutionPrecompute TF of each AIRS Spectral Response Function Ak, k=1..2378IASI calibrated spectra (L1B or L1C TBC) interferogram I0For each k, Sk=TF-1(I0/Af*Ak) , … AIRS like spectrum, interpolated at nuk• SAIRS_like (k)•

Af

is IASI apodisation function (G if L1C spectrum, self-apodisation if L1B spectrum)

■ValidationOver 2000 spectra from the TIGR dataset

0.3 K

-0.3 K

Red: stddev, Blue : Bias0.3 K

-0.3 K

Red: stddev, Blue : Bias

■

On-going activities1. Intercomparison with GCC/GSICS

results2. Increase the number of

comparison opportunities (generalization of the SNO concept)


Conclusions

■ After more than 17 months in orbitIASI is performing very well •

all mission requirements are met•

both instrument and processing

■ All performances very stable in the long termRadiometry, spectral, geometry

■ During the routine phase, IASI Technical Expertise Center (IASI TEC) located in CNES/Toulouse takes care of

In-depth Performance monitoringProcessing parameters updating

■ In parallel with the operational monitoring performed by the EUMETSAT EPS/CGS teams

Near Real TimeRadiances monitoring (wrt Radiative Transfer)


Spares


Date Mission outage Origine Sub- system Détails

15/05/2007 ~ 1day 5h SEU LAS Target LAS T° corruption, due to an SEU on CCE or LAS

13/06/2007 ~ 1day 7h SEU DPS DMC checksum error

20/07/2007 ~ 1day 9h SEU DPS DPC pixel 3A checksum error

01/11/2007 ~ 10h SEU DPS DPC pixel 4A checksum error

08/11/2007 ~ 11h SEU DPS DMC checksum error

18/11/2007 ~ 4days 9h SET DPS Communication error IMS-DPS with OOLs on DPS voltages due to an SET on DMC converter

04/02/2008 7h 50min SEU CCM Overflow on ALU computation. Error disapear after reset which confirms SEU, probably on CCE RAM

09/02/2008 3h 45min SEU DPS DPC pixel 3B checksum error

5 occurrences SEU OBDH OBDH corruption zone OBDH (EDAC counter anomalie) without mission outage

IASI outages : SEU/SET anomalies

■

Proton or Heavy ion events caused IASI to go into safe mode (1 or 2)

* long outage due to detectors temperature stabilization after safe mode 2

*


2007-06-13-10:23

SEU DMC memory

2007-07-20-04:31

SEU DPC 3A

2007-11-01-13:35

SEU DPC 4A

2007-11-08-11:03

SEU DMC memory

2007-11-18-01:31

SET DMC CV

2007-05-15-13:18

SEU laser

2008-02-04-12:46

SEU CCM ALU

2008-02-09-10:37

SEU DPC 3B


% in each mode between 07/05/07 and 03/31/08

Operational Modes 90 %

Normal OP 89%

External Calibration 1%

Non Operational Modes

10 % decontamination, IASI anomalies and platform anomalies

IASI availability in Operational modes

■

EUMETSAT / CNES / ALCATEL Working group has proposed recommendations for diminishing impact of SEU anomalies (on-board)

■

Before these recommendations are implementedStrong involvement of the EUMETSAT and CNES operational teams toreduce the duration of unavailability periodsE.g. IASI decontamination implemented consecutively to a plate-form anomaly to save 2 days in non operational modes

International TOVS Study Conference, 16th

, ITSC-16, Angra dos Reis, Brazil, 7-13 May 2008.

Madison, WI, University of Wisconsin-Madison, Space Science and Engineering Center,

Cooperative Institute for Meteorological Satellite Studies, 2008.

iasi fm2 on metop a performances after 1.5 year in...

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