Post on 30-Dec-2015
description
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
123rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
Contents
Brief introduction of HJ satellite and HSI senorCAL/VAL activities of HJ-1A/HSIChallenges Prospect
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009 2
Introduction
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009 3
““ 2+1”2+1”““ 2+1”2+1”22 optical optical moonletmoonletss22 optical optical moonletmoonletss
11 radarradar--moonletmoonlet11 radarradar--moonletmoonlet
first-stagefirst-stage
““4+4” 4+4” ““4+4” 4+4”
4 4 optical optical satellitesatellitess4 4 optical optical satellitesatellitess
44 radarradar satellite satellitess44 radarradar satellite satellitess
second-stagesecond-stage
• 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.
Introduction
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009 4
satellitesatellite HJ-1AHJ-1A HJ-1BHJ-1B
payloadpayload2 2 CCDs CCDs 2 2 CCDs CCDs
HSIHSI IRSIRS
orbital type sun-synchronous orbitorbital height ( km) 649.093orbital inclination 97.9486orbital period (minute) 97.5600circles per day 14+23/31revisiting period (hour)
CCD 96 (48 with HJ-1A/1B combination)HSI 96IRS 96coverage period (day) 31coverage period circles 457local time at descending node 10:30 AM ± 30min
The small satellite for environment and disaster ( HJ-1A) in China carried a hyper-Spectral Imaging (HSI) sensor, designed by Academy of Sciences, CAS
HJ-1A
Spectral range: 450nm-950nmBand number: 115 Spatial resolution: 100mSwath: 50kmSide-looking: ±30°Revisiting: 4-31days
Introduction
Principles of HSI
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009 6
On-orbit calibration
lamp
Integral sphere
Collimation lens
Ground object
Switch mirror
Object lens Slit
Sagnac prism
Fourier lens
Cylindrical lens
Detector
The imaging approach used by HSI is a spatially modulated Fourier transform method based on a Sagnac interferometer.
Onboard inner calibration mode and earth observation mode can be switched by a swing mirror.
Introduction
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009 7
Principles of HSIIntroduction
HSIImaging
SpectrumRebuild (base
on IFFT)
PushSweep
GroundObject(line)
Interferogram
Interferogramquence
SpectrumCube (115
bands)
Swath Width
Swath Width512
OPD256
115 band
nn
512
Imaging Parameters of HSI
ParametersHJ-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
Comparison of Parameters Between HJ-1A and EO-1
Introduction
823rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009
• 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 safetyWith the issues above we do need more sites and
more experiments to study the way to calibrate this new kind of sensor
CAL/VAL activities of HJ-1A/HSI
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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
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CAL/VAL activities of HJ-1A/HSI
Measure Target
Surface Properties
MeasureAtmospheric
Properties
Radiative Transfer Model- Modtran; 6S
Predicted At-Sensor Radiance (L)
Illumination+ Viewing
angles Sensor Signal (DN)
DN
LGain=dL/dDN
offset
Sensor’s spectral
response function
Vicarious calibration at Dunhuang Site
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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 12.8335
510.98 1.0400 577.87 1.6443 664.90 2.8501 782.81 4.1707 951.54 10.0017 12
Cross comparison at Dunhuang site
Between HJ-1A/HSI channels and corresponding MODIS bands
HSI Radiance
Cross comparision
Spectralconvolution
MODIS Radiance
HSI Convolved Radiance
Si te Registration
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009 13
HJ-1A/HSI and Terra/MODIS Image Pairs
MODIS channel 1
UTM 04:25 May 29,2009
HSI channel 73
UTM 04:41, May 29,2009870
pixels
180 pixels
Cross-comparison at Dunhuang site
23rd CEOS Plenary I Phuket, Thailand I 3-5 December 2009 14
CAL/VAL activities of HJ-1A/HSI
Spectral response of MODI S
0. 00
0. 20
0. 40
0. 60
0. 80
1. 00
400 500 600 700 800 900 1000
wavel ength nm( )
SRF/
Ref
HSI spectralcoverageMODI S channel 1
MODI S channel 2
MODI S channel 3
MODI S channel 4
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
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Cross-comparison at Dunhuang site
CAL/VAL activities of HJ-1A/HSI
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
distinction of observing geometry and atmosphere due to different acquisition time
Discrepancy
MODIS calibration accuracy
HSI calibration accuracy
1 2 3
16
Cross-comparison at Dunhuang site
CAL/VAL activities of HJ-1A/HSI
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 17
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.
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Anticipated agency participation HJ-1A/HSI image over Dome C area for example
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2009-09-13 23:59
scene Center Latitude: S74.676132°
scene Center Longitude:E124.513398°
solar altitude angle: 5.5°
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.
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