Infrared Atmospheric Sounding Interferometer
IASI on METOP
On-Ground Calibration of the FM2 Instrument
International TOVS Study Conference
25-31, May 2005
Beijing China
D. Blumstein1, B.Tournier2, T.Carlier1, T.Maciaszek1, T.Phulpin1,
G.Chalon1, P.Astruc3, D.Miras3, D.Siméoni3
(1) Centre National d'Etudes Spatiales (CNES), Toulouse, France
(2) NOVELTIS, Toulouse, France
(3) ALCATEL SPACE, Cannes, France
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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Outline
‰Key Performance specifications
‰On-ground characterization of IASI FM2
¾ First IASI instrument in flight (on METOP 2)
‰IASI Program Status
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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Key performances specifications
‰ Radiometric sensitivity
¾ Apodized and non-apodized spectra
‰ Radiometric accuracy
¾ Absolute accuracy
¾ Relative accuracy (at a given time)
ƒ Between pixels, channels, viewing direction
¾ Stability
‰ Spectral & geometry
¾ Spectral calibration
¾ Spectral response function
¾ Point Spread Function ( & interband registration)
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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Measured radiometric sensitivity
AVM result — IASI FM2 Noise Spectrum (NedT at 280 K) — Session SM0410060647 — CBS 91.7 K
‰ IASI FM2 testing in vacuum
non apodized (293 K scene)
1,0
ƒ Loss of transmission : 1.5 % at 850
cm-1 over a period of 6 days
ƒ Equivalent to the absorption by a
40 nm thin film of water ice
B1
0,8
0,7
NedT at 280 K (K)
¾ Detectors temperature 91.7 K
¾ Measured on blackbody
¾ No evolution of noise (ice cont.)
0,9
0,6
B2
B3
NeDT in K (at 280 K)
0,5
0,4
0,3
0,2
0,1
0,0
64500
82500
100500
118500
136500
154500
172500
190500
208500
226500
Wavenumber (m^-1)
Measurement SM0410111609 — Pixel 3
Mission radiometric performance in NeDT — T_CBS=91,7 K — (IASI FM2 OV Test)
apodized + pseudo-noise
1.0
0,8
0.9
Noise Spectrum in NedT at 280 K after drift correction - P4 - c10693_avm_SM0410060647
Effect of
scene
temperature
on B3 noise
(scene at 240 & 280 K)
Noise Spectrum
in NedT
at 280
K after drift correction
- P1 - c10693_avm_SM0410060647
Noise Spectrum in NedT at 280 K after drift correction - P3 - c10693_avm_SM0410060647
NedT at 280 K
Noise Spectrum in NedT at 280 K after drift correction - P2 - c10693_avm_SM0410060647
NedT at 280 K
measurements
0,7
0.8
0,6
NeDT at 280 K (K)
NeDT at 280 K (K)
0.7
0.6
0.5
0.4
0,5
0,4
0,3
0.3
0,2
0.2
0,1
0.1
0.0
645
845
1045
1245
1445
1645
1845
Wavenumber (cm-1)
Spécification
ITSC-14 – Beijing, 25-31May. 2005
FM2 (Delta-QR)
2045
2245
0,0
1900
1950
2000
2050
2100
2150
2200
2250
2300
2350
Wavenumber (cm-1)
240 K
280 K
spec
D. Blumstein – CNES DCT/PO/EV
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2400
Measured radiometric accuracy (1/4)
Session SM 06 22h59 — T_HBB about 299 K, no Non-Linearity correction
300,2
‰ IASI FM2 testing in vacuum
300,0
299,6
B1
299,4
299,2
299,0
298,8
Session SM 06 22h59 — T_HBB around 299 K, Non-Linearity correction applied
300,2
Pixel 1
300,0
298,6
298,4
298,2
645
ƒ Result valid for other incidences
¾ Post-calibration done by Level 1 proc.
to achieve "differential" requirements
Pixel 2
Pixel 3
Pixel 4
2045
2245
299,8
845
1045
1245
1445
1645
299,6
Wave numbers (cm-1)
NL (B1)
corrected
Brigthness temperature (K)
¾ Need for NL correction in B1 band
¾ DT < 0.25 K
¾ Target in nadir position
Brigthness temperature (K)
299,8
1845
299,4
299,2
299,0
298,8
298,6
ƒ Between pixels, scan views or channels
Pixel 1
Pixel 2
1645
1845
Pixel 3
Pixel 4
2045
2245
298,4
298,2
645
845
1045
1245
1445
Wave numbers (cm-1)
Tscene : 220 – 300 K
Pixel 1, Nominal Conf., Cold Case
0 .5
0 .4
H B B c o a t i n g e m i s s iv it y l o s s
0 .2
B B C c o a t i n g e m i s s i v i t y lo s s
0 .1
0
-0 .1
-0 .2
-0 .3
-0 .4
300 K
294 K
280 K
260 K
0 .4
0 .3
B B C c o a t i n g e m is s i v it y l o s s
H B B c o a t i n g e m i s s iv i t y lo s s
0 .2
0 .1
0
- 0 .1
- 0 .2
- 0 .3
- 0 .4
300
294
280
260
240
240 K
220 K
-0 .5
64500
0 .5
Radiometric Calibration Error in NedT at 280 K (K)
Radiometric Calibration Error in NedT at 280 K (K)
0 .3
Tscene : 240 – 300 K
Pixel 1, Redundant Conf., Hot Case
114500
164500
W a v e N u m b e r (m ^ -1 )
ITSC-14 – Beijing, 25-31May. 2005
214500
264500
- 0 .5
64500
114500
164500
214500
264500
W a v e N u m b e r (m ^ -1 )
D. Blumstein – CNES DCT/PO/EV
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Measured radiometric accuracy (2/4)
‰ Raw measurements versus model comparison
Pixel 1
Nominal Conf.
Cold Case
0 .5
0 .4
H B B c o a tin g e m is s iv ity lo s s
0 .2
B B C c o a tin g e m is s iv ity lo s s
0 .1
0
-0 .1
Radiometric Calibration Error Model — Nominal configuration, Cold Case
T_env HBB = 280 K, T_env BBC = 275 K, T_env CBB = 230 K
-0 .2
-0 .3
-0 .4
300 K
294 K
280 K
260 K
0.5
240 K
220 K
-0 .5
64500
0.4
114500
164500
214500
W a v e N u m b e r (m ^ -1 )
264500
0.3
DT at 280 K (Kelvin)
Radiometric Calibration Error in NedT at 280 K (K)
0 .3
0.2
0.1
0.0
645
-0.1
1145
1645
2145
2645
-0.2
-0.3
-0.4
-0.5
Wave Number (cm-1)
220 K
ITSC-14 – Beijing, 25-31May. 2005
240 K
260 K
280 K
294 K
300 K
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Measured radiometric accuracy (3/4)
‰ Raw measurements versus model comparison
Pixel 1
Redundant Conf
Hot Case
0 .5
0 .3
B B C c o a tin g e m is s iv ity lo s s
H B B c o a t in g e m is s iv it y lo s s
0 .2
0 .1
0
-0 .1
Radiometric Calibration Error Model — Redundant configuration, Hot Case
T_env HBB = 295 K, T_env BBC = 285 K, T_env CBB = 230 K
-0 .2
-0 .3
-0 .4
300
294
0.5
280
260
0.4
240
-0 .5
64500
114500
0.3
164500
W a v e N u m b e r (m ^ -1 )
214500
DT at 280 K (Kelvin)
Radiometric Calibration Error in NedT at 280 K (K)
0 .4
264500
0.2
0.1
0.0
645
-0.1
1145
1645
2145
2645
-0.2
-0.3
-0.4
-0.5
Wave Number (cm-1)
240 K
ITSC-14 – Beijing, 25-31May. 2005
260 K
280 K
294 K
300 K
D. Blumstein – CNES DCT/PO/EV
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Measured radiometric accuracy (4/4)
‰ More in-depth verifications performed during the test
¾ Scan angle effect verified
¾ Interpixel & interscan calibration
¾ Sensitivity to thermal drifts
ƒ Simulation of Entry/Exit of eclipse
‰ Mission Objectives on radiometric calibration are expected to be
achieved in orbit
¾ Absolute Calibration Error : < 0.5 K
¾ Intercalibration error at a given time : < 0.2 K
ƒ All geophysical conditions
ƒ 4 pixels, all viewing directions, all channels
¾ Intercalibration error over time : < 0.3 K
ƒ Short term (orbital period)
ƒ Long term
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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Measured Spectral Response Function
‰ IASI PFM testing in vacuum
B1 ISRF (944 cm-1)
¾ 2 laser beams (B1:CO2, B3:HF/DF)
4,0
ƒ Field and Aperture illuminated
3,0
ƒ Resolution (FWHM) compliant (w. margins)
ƒ ISRF Model accuracy achieved
ƒ ISRF Model input are precisely measured
• Instrument Point Spread Function
• Interferometric axis and shear
• Corner Cube trajectory
Measured P1
Model P1
0,03
Normalised to Surface
¾ ISRF measured on +/- 16 cm-1 (+)
3,5
2,5
0,02
0,01
0,00
2,0
-15,0
-14,5
-14,0
-13,5
-13,0
-0,01
-0,02
1,5
-0,03
-0,04
1,0
0,5
0,0
-0,5
-1,0
-16,00
-12,00
-8,00
-4,00
0,00
4,00
8,00
12,00
16,00
Wave numbers (cm-1)
B3 ISRF (2655 cm-1)
3,0
2,5
Measured P1
0,20
Model P1
0,15
Normalised to Surface
2,0
0,10
0,05
0,010
1,5
0,00
0,005
0,000
-15,0
-14,5
-14,0
-13,5
-0,05
-13,0
-4
-2
0
2
4
-0,005
-0,10
-0,010
1,0
-0,15
-0,015
-0,020
-0,20
-0,025
0,5
0,0
-0,5
-16,00
-12,00
-8,00
-4,00
0,00
4,00
8,00
12,00
16,00
Wave numbers (cm-1)
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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Measured Spatial Response Function
‰ Point Spread Function (IPSF) measured for the 3 IASI bands
‰ Interband registration verified
¾ Integrated absolute difference < 0.03
‰ 12 km FOV
(at nadir)
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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Spectral Performances (1/3)
‰ First assessment done on few parameters
¾ Dν/ν with respect to nominal instrument
¾ Spectral resolution (Full Width at Half Maximum)
ƒ At 944 cm-1 (B1) and 2655 cm-1 (B3)
¾ Shape error index Epsilon2 = variations of the ISRF
ƒ Absolute difference between average and instantaneous
ƒ Summed over +/- 16 cm-1
Band 1
Dν/ν
FWHM
Epsilon2
P1
-1
cm
cd0
cd1
Band 3
Dν/ν
FWHM
Epsilon2
ITSC-14 – Beijing, 25-31May. 2005
0.32
0.014
0.015
P1
-1
cm
cd0
cd1
0.43
0.020
0.020
P2
P3
-5
1 10
0.32
0.32
0.014
0.010
0.013
0.009
P2
P3
-5
1 10
0.40
0.43
0.025
0.015
0.023
0.011
P4
0.32
0.011
0.012
Specification
-4
2 10
0.35
0.026
P4
-4
2 10
0.42
0.019
0.014
0.48
0.042
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Spectral Performances (2/3)
‰ Spectral stability over 80 sec. Spec = 1.10-6
¾ Standard deviation of the position of the quadratic barycentre of the ISRF
Band 1
cd0
cd1
P1
8.27E-08
7.66E-08
P2
8.30E-08
7.46E-08
P3
7.70E-08
4.79E-08
P4
7.36E-08
8.08E-08
Band 3
cd0
cd1
P1
1.67E-08
1.58E-08
P2
2.29E-08
2.55E-08
P3
2.36E-08
2.09E-08
P4
1.66E-08
1.49E-08
‰ + very good long term stability between measurement sessions
¾ Observed Dν/ν (average of the 4 pixels) < 1.10-6
¾ Hot Case / Cold Case
¾ 14 days between first and last measurements
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Spectral Performances (3/3)
‰ Shape error index 1 Spec b1 < 0.02, Spec b3 < 0.05
¾ ISRF knowledge errors
¾
Shape_index_1 = Σ( abs( Isrf_Model(n) – Isrf_Average(n) ) * dn )
ƒ Ghost has to be removed from the averaged ISRF (computation on 13 cm-1)
Band 1
+/- 13 cm
+/- 16 cm
cd0
cd1
cd0
cd1
P1
0.025
0.029
0.034
0.034
P2
0.023
0.023
0.031
0.028
P3
0.023
0.021
0.026
0.023
P4
0.023
0.022
0.027
0.024
cd0
cd1
cd0
cd1
P1
0.029
0.032
0.043
0.039
P2
0.042
0.046
0.053
0.056
P3
0.026
0.019
0.030
0.021
P4
0.049
0.050
0.056
0.053
Band 3
+/- 13 cm
+/- 16 cm
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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Summary
‰ Excellent performances measured on 2nd IASI model (FM2)
¾ The instrument ran flawlessly for the 3 weeks of test
¾ Design modifications decided after PFM testing (ice contamination)
successfully implemented on FM2 & FM3
• PFM model will be refurbished to benefit from these modifications
¾ Big investment put into the on-ground calibration (human & financial)
¾ Excellent stability of the instrument (spectral & radiometric)
¾ Spectral Response Function of the instrument
• Accurately measured at 2 wavenumbers (use of 2 laser beams for test)
• Model accuracy verified at these 2 wavenumbers
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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IASI Project Status : instruments (1/2)
‰ FM2
¾ On-ground calibration completed (TVAC test in October 2004)
¾ Integration & tests on METOP 2 completed
¾ Launch planned April 2006
‰ FM3
¾ Subsystem Integration & Test completed
¾ Thermal Vacuum Test planned in October 2005
‰ PFM
¾
¾
¾
¾
Instrument TVAC test in June 2003
METOP Payload TVAC test in February 2004
Now dismounted from METOP 2
Detectors refurbishment planned end of year 2005
ITSC-14 – Beijing, 25-31May. 2005
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IASI Project Status : system (2/2)
‰ OPS software (Level 1 processing)
¾ Delivered by CNES to EUMETSAT : Sept. 2004
¾ Now integrated & tested in CGS
¾ Delivered to METEO FRANCE for integration in direct readout software
‰ TEC (IASI Technical Expertise Center)
¾ Acceptance test completed : Feb. 2005
¾ NRT terminal installed. First tests completed
¾ TEC ready for system level testing with EPS/CGS
‰ Participation of IASI Instrument team to EPS system level tests with
METOP 2 (SSVT4a, May 2005)
‰ In-flight commissioning preparation
¾ Instrument on-orbit Verification Plan completed
¾ Level 1 Cal/Val Plan completed (see poster B20), implementation on-going
ITSC-14 – Beijing, 25-31May. 2005
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Aknowledgements
‰ The authors would like to express their thanks to the many
people involved in the development, integration and test of the
IASI instruments either in the industry, in the space agencies or
in the universities for their efforts which made IASI a reality.
‰ A special thought goes to F.R.Cayla who has been so involved
with IASI project since the beginning and is still very close from
us in spite of his retirement four years ago.
ITSC-14 – Beijing, 25-31May. 2005
D. Blumstein – CNES DCT/PO/EV
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