Progress of in-flight Calibration of
HJ-1A/HSI
Li Chuanrong
Invited expert of NRSCC
Professor and Vice President
Academy of Opto-Electronics,CAS
Phuket, Nov 03, 2009
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Contents
Brief introduction of HJ satellite and HSI senor
CAL/VAL activities of HJ-1A/HSI
Challenges
Prospect
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Introduction
first-stage
second-stage
“2+1”
“4+4”
2 optical moonlets
4 optical satellites
1 radar-moonlet
4 radar satellites
•
On 2008.09.06, the small satellite constellation HJ -1A/1B were launched
by a single LM-2C (CZ-2C) launch vehicle.
•
On 2009.03.30, HJ -1A/1B were ready for operational applications.
•
HJ -1C will launch soon.
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Introduction
satellite
payload
HJ-1A
HJ-1B
2 CCDs
2 CCDs
HSI
IRS
orbital type
sun-synchronous orbit
orbital height（km）
649.093
orbital inclination
97.9486
orbital period (minute)
97.5600
circles per day
14+23/31
revisiting period
(hour)
CCD
96 (48 with HJ-1A/1B combination)
HSI
96
IRS
96
coverage period (day)
31
coverage period circles
457
local time at descending node
10:30 AM ± 30min
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Introduction
HJ-1A
The small satellite for
environment and disaster ( HJ1A) in China carried a hyperSpectral Imaging (HSI) sensor,
designed by Academy of
Sciences, CAS
Spectral range: 450nm-950nm
Band number: 115
Spatial resolution: 100m
Swath: 50km
Side-looking: ±30°
Revisiting: 4-31days
Introduction
Principles of HSI
The imaging approach
Integral sphere
used by HSI is a spatially
modulated Fourier
On-orbit
calibration
lamp
Collimation lens
transform method based
on a Sagnac interferometer.
Sagnac prism
Switch mirror
Object lens
Onboard inner calibration
Slit
Fourier lens
mode and earth
Cylindrical lens
observation mode can be
Detector
switched by a swing mirror.
Ground object
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Introduction
Principles of HSI
Interferogram
Ground
Object(line)
HSI
Imaging
OPD
256
Swath Width
Swath Width
512
Push
Sweep
115 band
Spectrum
Rebuild (base
on IFFT)
n
n
512
Spectrum
Cube (115
bands)
Interferogram
quence
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Introduction
Imaging Parameters of HSI
Comparison of Parameters Between HJ-1A and EO-1
Parameters
HJ-1A
EO-1
CCD
HSI
ALI
Hyperion
Spectral Range
430-900nm
450-950nm
400-2400nm
400-2500nm
Spatial Resolution
30m
100m
30m
30m
Swath Width
360km
50km
36km
7.5km
Spectral Resolution
--
~4.3nm
--
~10nm
Number of Bands
4
115
10
220
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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CAL/VAL activities of HJ-1A/HSI
• Calibration requirement to HSI:
New imaging system and mechanism—We have
less experiences
We have not carried out on board calibration
with consideration of instrument safety
With the issues above we do need more sites and
more experiments to study the way to calibrate
this new kind of sensor
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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CAL/VAL activities of HJ-1A/HSI
Vicarious calibration activities
• Dunhuang Site (twice after launch)
– 40.08N, 94. 38E
– Altitude: 1200m
– 2008.10.14-2008.10.22 (Gain level 1)
– 2009.08.19-2009.08.29 (Gain level 2)
• Inner Mongolia (once for validation)
– 2009.09
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Vicarious calibration at Dunhuang Site
Sensor’s
spectral
response
function
Measure
Target
Surface Properties
Illumination
+ Viewing
angles
Measure
Atmospheric
Properties
Sensor
Signal (DN)
Radiative Transfer Model
- Modtran; 6S
Predicted At-Sensor
Radiance (L)
L
offset
Gain=dL/dDN
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
DN
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Radiometric vicarious calibration results of HSI（Gain1)
WL(nm)
Gain
WL(nm)
Gain
WL(nm)
Gain
WL(nm)
Gain
WL(nm)
Gain
460.04
0.2927
513.56
1.0333
581.18
1.7071
669.29
2.9618
788.89
4.4275
462.14
0.3050
516.17
1.1463
584.52
1.7016
673.73
3.0574
795.07
4.6644
464.25
0.3447
518.81
1.1874
587.90
1.7869
678.23
3.0978
801.34
4.6438
466.38
0.3786
521.48
1.1288
591.33
1.9722
682.79
3.1684
807.72
4.5858
468.53
0.4018
524.17
1.1658
594.79
2.0156
687.41
3.4454
814.20
4.9406
470.71
0.4296
526.89
1.2008
598.30
1.9759
692.10
4.3658
820.78
6.4526
472.90
0.4713
529.64
1.2321
601.85
1.9553
696.85
3.9148
827.47
5.5252
475.11
0.5059
532.42
1.2460
605.44
1.9843
701.66
3.8392
834.27
5.3826
477.35
0.5022
535.22
1.3309
609.07
2.0150
706.54
3.8968
841.18
4.5829
479.60
0.5239
538.06
1.2698
612.74
2.1141
711.50
3.7569
848.20
4.3767
481.88
0.6020
540.92
1.4228
616.46
2.2630
716.52
3.7909
855.35
4.4874
484.18
0.6329
543.82
1.3548
620.23
2.1945
721.61
5.8620
862.62
4.2436
486.50
0.7557
546.75
1.3759
624.04
2.1912
726.77
5.1258
870.01
4.3057
488.84
0.7367
549.71
1.4898
627.90
2.3906
732.01
5.5057
877.53
4.1998
491.20
0.7456
552.70
1.4741
631.81
2.4263
737.33
4.3242
885.18
4.1541
493.59
0.8194
555.73
1.4915
635.76
2.4634
742.73
4.1700
892.96
4.0919
496.00
0.7721
558.79
1.5827
639.77
2.4562
748.20
3.9960
900.89
5.7221
498.44
0.8276
561.88
1.5462
643.82
2.5488
753.75
3.9403
908.95
5.6478
500.90
0.8993
565.00
1.5896
647.93
2.7137
759.39
3.8426
917.16
6.2722
503.38
0.9542
568.16
1.6073
652.09
2.9064
765.11
11.5210
925.52
4.7639
505.89
0.9832
571.36
1.6783
656.31
2.9426
770.92
4.5856
934.04
7.7071
508.42
1.0366
574.60
1.5987
660.58
2.9840
776.82
4.0644
942.71
510.98
1.0400
577.87
1.6443
664.90
2.8501
782.81
4.1707
951.54
12.8335 12
10.0017
Cross comparison at Dunhuang site
Between HJ-1A/HSI channels and corresponding MODIS bands
Site
Registration
MODIS Radiance
HSI Radiance
Cross comparision
Spectral
convolution
HSI Convolved
Radiance
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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CAL/VAL activities of HJ-1A/HSI
Cross-comparison at Dunhuang site
HSI channel 73
870 pixels
UTM 04:41, May 29,2009
MODIS channel 1
180 pixels
UTM 04:25 May 29,2009
HJ-1A/HSI and Terra/MODIS Image Pairs
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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CAL/VAL activities of HJ-1A/HSI
Cross-comparison at Dunhuang site
Spectral response of MODIS
1.00
SRF/Ref
0.80
0.60
HSI spectral
coverage
MODIS channel 1
0.40
MODIS channel 2
MODIS channel 3
0.20
MODIS channel 4
0.00
400
500
600
700
800
900
1000
wavelength（nm）
MODIS channel 1
HSI channels 57-74
MODIS channel 2
HSI channels 98-109
MODIS channel 3
HSI channels 1-11
MODIS channel 4
HSI channels 34-43
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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CAL/VAL activities of HJ-1A/HSI
Cross-comparison at Dunhuang site
MODIS observed radiance
HSI-convolved radiance
MODIS channel 1
112.6021
109.5861
MODIS channel 2
74.00458
65.9016
MODIS channel 3
126.2463
135.7682
MODIS channel 4
120.6291
123.0256
Discrepancy
1
distinction of
observing
geometry and
atmosphere due
to different
acquisition time
2
HSI
calibration
accuracy
3
MODIS
calibration
accuracy
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Current challenges
Uncertainties in radiometric vicarious
calibration
Radiometric cross-calibration method based
on other well-calibrated satellite data is to be
studied
Spectral calibration is to be expected
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Prospect
 Invited by former WGCV group chair Dr. Cao Changyong, we
will take part in Antarctic Dome C project on behalf of
NRSCC
 The actions including confirmation of coverage area of
Antarctic region and planning of data acquisition in Dec. of
this year has been carried out
 By working on this project, AOE, as technical and operational
facilitator of NRSCC, is willing to join the actions of CEOS
WGCV.
 AOE will also be pleasant to technically bridge the action
cooperation between CEOS and China related agencies, such
as data democracy, calibration, validation, virtual
constellation etc.
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Anticipated agency participation
HJ-1A/HSI image over Dome C area for example
2009-09-13 23:59
scene Center Latitude: S74.676132°
scene Center Longitude:E124.513398°
solar altitude angle: 5.5°
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Anticipated agency participation
Near-term plans
Provide related HJ-1A/HSI data and technical parameters
support, so as to enrich datasets about the Dome C site.
In accordance with the procedure of CEOS/WGCV, carry
out the cross-calibration studies between HJ-1A/HSI and
other well-calibrated visible/near infrared sensors based
on the Antarctic Dome C calibration site.
Invite foreign calibration experts including those work for
CEOS to go to China for scientific discussion periodically.
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
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Thank you !