-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
In-Flight Performance of the TanSat Atmospheric Carbon
DioxideGrating Spectrometer
Zhong-Dong Yang, Yan-Meng Bi, Qian Wang, Cheng-Bao Liu, Song-Yan
Gu,Yu-Quan Zheng, Chao Lin, Zeng-Shan Yin, Long-Fei Tian
National Satellite Meteorological Center/CMA, CHINA15th
International Workshop on Greenhouse Gas Measurements from
Space@Hokkaido University
Yang, Zhongdong etc.: [email protected]
National Satellite Meteorological Center, CMA
May 28, 2019
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
1 Introduction
2 Performance specifications of the TanSat ACGS
3 In-flight performance of the TanSat ACGSSpectroscopic
performanceRadiometric performance
4 Validation of ACGS XCO2
5 Summary
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Introduction
Figure: Physical photograph of the in-flight ACGS
1 TanSat is the first Chinese satellite missiondedicated to
measuring the column-averagedCO2 dry-air mole fraction (XCO2 ); for
thispurpose, TanSat is equipped with theAtmospheric Carbon Dioxide
GratingSpectrometer (ACGS), a major spacebornegrating hyperspectral
spectrometer suite.
2 TanSat was successfully launched into orbit fromJiuQuan Base
in Gansu Province, China, on 22December 2016.
3 The ACGS has been providing globalmeasurements of CO2 and O2
spectral bands inreflected sunlight since early February 2017.
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Introduction...
1 The ACGS measurements are calibrated and geolocated to produce
level 1 (L1)products that are analyzed to retrieve spatially
resolved estimates of XCO2 .
2 It is important that the radiometric and spectroscopic
accuracies of the ACGS bemeticulously validated.
3 These demanding applications represent the motivation for the
characterization ofthe ACGS radiometric and spectroscopic
accuracies provided in this presentation.
4 In addition to understanding the physical basis of the
uncertainties in ACGSmeasurements, it should be possible to achieve
even higher accuracies inspace-based atmospheric CO2 measurements
in the near future.
5 Since TanSat was launched in 2016, a team of subject matter
experts from thegovernment, academic, and industrial sectors has
been engaged in in-flight TanSaton-orbit checks that include ACGS
calibration and validation activities.Consequently, an on-orbit
check was completed in September 2017.
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Performance specifications of the TanSat ACGS
ItemBand
O2A WCO2 SCO2
Spectral Range (nm) 758 - 778 1594 - 1624 2042 - 2082Spectral
Resolution (nm) 0.033 - 0.047 0.120 - 0.142 0.160 - 0.182Spectral
Resolving (λ/∆λ) ∼19000 ∼12800 ∼12250Spectral Sampling Per FWHM
> 2Dynamic Range(ph/sec/m2/sr/um)
SNR=1 a©1.2 × 1017 ∼1.4 × 1021
SNR=1 a©5.7 × 1016 ∼4.9 × 1020
SNR=1 a©6.0 ×1016 ∼ 1.6×20
SNR @ (ph/sec/m2/sr/um) 360 a©5.8 × 1019 250 a©2.1 × 1019 180
a©1.1 × 1019Abs/Rel Calibration Error(%)
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
In-flight performance of the TanSat ACGS
1 The in-flight performance and absolute accuracy of any remote
sensing satelliteinstrument are based on the optimal design of the
optics, electricity andthermotics systems, ground laboratory
calibration, and in-flight refinement of thecalibration
parameters.
2 The performance of the ACGS was carefully characterized and
calibrated twiceprior to launch, and the results met the mission
requirements [?].
3 The ACGS has performed as expected on orbit. During the first
month followingits launch in 2016, the spacecraft team completed a
functional check of theplatform and instruments.
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
Spectroscopic performance
1 During the flight of TanSat, we used the available Fraunhofer
lines of the solarspectrum acquired during solar calibration
observations of the ACGS aftercorrecting for the Doppler effect and
performed a comparison with the moreprecise solar spectra database
used by OCO-2 as references to validate thespectral accuracy of the
centroid wavelength.
2 These figures illustrate remarkable consistencies among the
footprints andagreements with the reference spectrum. The spectral
calibration accuracy of theO2 A-band is 0.19 pm, that of the WCO2
band is 0.27 pm, and that of the SCO2band is 4.75 pm, all of which
meet the 0.05 FWHM requirement. Thespectroscopic performance of the
ACGS therefore surpasses mission requirementswith a margin.
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
Spectroscopic performance of the ACGS O2 A-band
758 760 762 764 766 768 770 7721.8
2.0
2.2
2.4
2.6
2.8
3.0(P
h/S/m2/sr/um)
1e20 Solar Diffuser Measurement of ACGS O2 A band Radiance
758 760 762 764 766 768 770 7721.8
2.0
2.2
2.4
2.6
2.8
3.0
(Ph/S/m2/sr/um)
1e20 Toon O2 A band Solar Radiance
758 760 762 764 766 768 770 772(nm)
−1.00
−0.75
−0.50
−0.25
0.00
0.25
0.50
0.75
1.00
Diff. (Ph
/S/m
2/sr/um)
1e19 Difference between ACGS and Toon spectrum radiance of O2 A
band
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9Yang, Zhongdong etc.:
[email protected] In-Flight Performance of the TanSat Atmospheric
Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
Spectroscopic performance of the ACGS WCO2 band
1595 1600 1605 1610 1615 16201.1
1.2
1.3
1.4
1.5
1.6
(Ph/S/m2/sr/um)
1e20 Solar Diffuser Measurement of ACGS WCO2 band Radiance
1595 1600 1605 1610 1615 1620
1.2
1.3
1.4
1.5
(Ph/S/m2/sr/um)
1e20 Toon WCO2 band Solar Radiance
1595 1600 1605 1610 1615 1620(nm)
−1.00
−0.75
−0.50
−0.25
0.00
0.25
0.50
0.75
1.00
Diff. (Ph
/S/m
2/sr/um)
1e19 Difference between ACGS and Toon spectrum radiance of WCO2
band
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9Yang, Zhongdong etc.:
[email protected] In-Flight Performance of the TanSat Atmospheric
Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
Spectroscopic performance of the ACGS SCO2 band
2045 2050 2055 2060 2065 2070 2075 2080
7.8
8.0
8.2
8.4
8.6
8.8
9.0
9.2
9.4
(Ph/S/m2/sr/um)
1e19 Solar Diffuser Measurement of ACGS SCO2 band Radiance
2045 2050 2055 2060 2065 2070 2075 2080
7.8
8.0
8.2
8.4
8.6
8.8
9.0
9.2
(Ph/S/m2/sr/um)
1e19 Toon SCO2 band Solar Radiance
2045 2050 2055 2060 2065 2070 2075 2080(nm)
−3
−2
−1
0
1
2
3
Diff. (Ph
/S/m
2/sr/um)
1e18 Difference between ACGS and Toon spectrum radiance of SCO2
band
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9Yang, Zhongdong etc.:
[email protected] In-Flight Performance of the TanSat Atmospheric
Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
Dark current
1 Dark current constitutes the response of an instrument
detector when it is notactively being irradiated, It is the
baseline of instrument radiometric response.
2 For the HgCdTe detectors of the WCO2 and SCO2 bands of the
ACGS, theresponse component is sensitive to tiny changes in the
ambient temperature,although the temperature is controlled to
within 0.3 K in-flight, and thus, it mustbe corrected routinely on
orbit.
3 Preliminary dark current responses as a function of the
ambient temperature wereestablished for the two CO2 bands during
the thermal-vacuum (TVAC) testing ofthe ACGS [Yang2018].
4 The response models of each channel in the two CO2 bands were
rebuilt usingin-flight data measured in real time during the first
phase of orbital checkoutthrough a few days of continuous
full-orbit, in-flight dark current response testing.
5 These models have been used in the preprocessing algorithm of
the ACGS L1products, and the performance has been validated in our
XCO2 retrievalprocessing. After the corrections used in these
models, the dark current error wasbelow 5 counts in the two CO2
bands of the ACGS.
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
Dark current model of WCO2(left) and SCO2(right) band
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
SNR and gain coefficient
1 The SNR is a measurement that compares the level of desired
signal to the levelof background noise, that is, the SNR measures
the ratio between an arbitrarysignal level and noise.
2 Measuring the SNR requires the selection of a reference signal
source. In theprelaunch calibration of the ACGS, we used a National
Institute of Standards andTechnology (NIST)-traceable integrating
sphere as the reference signal source tocharacterize the SNR
successfully[Yang2018].
3 In flight, we used measurements of the calibration lamp
devices and solar diffuserto evaluate the SNR of the ACGS. In our
work, the SNR is defined as the ratio ofthe mean to the standard
deviation of a measured signal.
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
In-flight performance stability of O2 A-band(left: from
calibration lamp,right: from solar diffuser)
1.05
1.06
1.07
1.08
1.09
Mea
n(Ph
/S/m
2/sr
/um
)
1e19 Mean Value of O2A from Lamp
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
1
2
3
NEdR
(Ph/
S/m
2/sr
/um
)
1e17 Noise of O2A from Lamp
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
201702
10
201703
10
201704
10
201705
10
201706
10
201707
10
201708
10
201709
10
201710
11
201711
10
201712
10
201801
10
201802
11
201803
10
201804
10
201805
11
201806
10
200
400
600
SNR
SNR of O2A from Lamp
2.95
3.00
3.05
3.10
3.15
3.20
Mea
n(Ph
/S/m
2/sr
/um
)
1e20 Mean Value of O2A from Solar Diffuser
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
1
2
3
4
NEdR
(Ph/
S/m
2/sr
/um
)
1e17 Noise of O2A from Solar Diffuser
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
201702
10
201703
10
201704
10
201705
10
201706
10
201707
10
201708
10
201709
10
201710
11
201711
10
201712
10
201801
10
201802
11
201803
10
201804
10
201805
11
201806
10
1000
2000
3000
4000
SNR
SNR of O2A from Solar Diffuser
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
In-flight performance stability of WCO2 band(left: from
calibrationlamp;,right: from solar diffuser)
3.0
3.1
3.2
3.3
Mea
n(Ph
/S/m
2/sr
/um
)
1e19 Mean Value of WCO2 from Lamp
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
1
2
3
NEdR
(Ph/
S/m
2/sr
/um
)
1e17 Noise of WCO2 from Lamp
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
201702
10
201703
10
201704
10
201705
10
201706
10
201707
10
201708
10
201709
10
201710
11
201711
10
201712
10
201801
10
201802
11
201803
10
201804
10
201805
11
201806
10200
400
600
800
1000
SNR
SNR of WCO2 from Lamp
1.500
1.525
1.550
1.575
1.600
1.625
Mea
n(Ph
/S/m
2/sr
/um
)
1e20 Mean Value of WCO2 from Solar Diffuser
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
1
2
3
4
NEdR
(Ph/
S/m
2/sr
/um
)
1e17 Noise of WCO2 from Solar Diffuser
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
201702
10
201703
10
201704
10
201705
10
201706
10
201707
10
201708
10
201709
10
201710
11
201711
10
201712
10
201801
10
201802
11
201803
10
201804
10
201805
11
201806
101000
2000
3000
4000
5000
6000
SNR
SNR of WCO2 from Solar Diffuser
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
In-flight performance stability of SCO2 band(left: from
calibration lamp,right: from solar diffuser)
2.3
2.4
2.5
2.6
Mea
n(Ph
/S/m
2/sr
/um
)
1e19 Mean Value of SCO2 from Lamp
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
1
2
3
NEdR
(Ph/
S/m
2/sr
/um
)
1e17 Noise of SCO2 from Lamp
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
201702
10
201703
10
201704
10
201705
10
201706
10
201707
10
201708
10
201709
10
201710
11
201711
10
201712
10
201801
10
201802
11
201803
10
201804
10
201805
11
201806
10
200
400
600
800
SNR
SNR of SCO2 from Lamp
8.6
8.8
9.0
9.2
9.4
Mea
n(Ph
/S/m
2/sr
/um
)
1e19 Mean Value of SCO2 from Solar Diffuser
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
1
2
3
4
NEdR
(Ph/
S/m
2/sr
/um
)
1e17 Noise of SCO2 from Solar Diffuser
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
20170210201703
10201704
10201705
10201706
10201707
10201708
10201709
10201710
11201711
10201712
10201801
10201802
11201803
10201804
10201805
11201806
10
1000
2000
3000
4000
SNR
SNR of SCO2 from Solar Diffuser
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Spectroscopic performanceRadiometric performance
Normalized to AU Radiance of ACGS Solar Diffuser Measurement
0 2 4 6 8 10 12 14 162.95
3.00
3.05
3.10
3.15
3.20
Mea
n(Ph
/S/m
2/sr
/um
)
1e20 Solar Diffuser Measurement of O2 A band Normalized to AU
Radiance
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
0 2 4 6 8 10 12 14 161.50
1.52
1.54
1.56
1.58
1.60
1.62
Mea
n(Ph
/S/m
2/sr
/um
)
1e20 Solar Diffuser Measurement of WCO2 band Normalized to AU
Radiance
FP1 FP2 FP3 FP4 FP5 FP6 FP7 FP8 FP9
20170210
20170310
20170410
20170510
20170610
20170710
20170810
20170910
20171011
20171110
20171210
20180110
20180211
20180310
20180410
20180511
20180610
8.58.68.78.88.99.09.19.29.39.4
Mea
n(Ph
/S/m
2/sr
/um
)
1e19 Solar Diffuser Measurement of SCO2 band Normalized to AU
Radiance
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Validation of ACGS XCO2 Using Target Observation Model of
TanSat
39.3°N
39.8°N
40.3°N
40.8°N
115.52°E 116.02°E 116.52°E 117.02°E
FY3D/MERSI-II: 20180531_0450 20180531_0455TanSat/ACGS :
20180531_0514 20180531_0521
SampleNum.=7761μ=406.2200σ=0.0446Num3σ/Num.=0.9937
0.0 0.03 0.05 0.08
406.10
406.15
406.20
406.25
406.30
XCO2(ppm
)
39.3°N
39.8°N
40.3°N
40.8°N
115.52°E 116.02°E 116.52°E 117.02°E
FY3D/MERSI-II: 20180620_0510 20180620_0515TanSat/ACGS :
20180620_0501 20180620_0508
SampleNum.=5960μ=404.0303σ=0.0660Num3σ/Num.=0.9854
0.0 0.08 0.17403.8
403.9
404.0
404.1
404.2
XCO2(ppm
)
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Validation to ACGS XCO2(3σ) at Beijing Ground Station in
2018
Date FTS125HR (ppm) ACGS(ppm) Precision(ppm) Bias(ppm)
Samples(n) Confidence
Mar. 08 407.71 408.00 1.15 -0.29 9074 95.54%
Apr. 16 409.87 408.62 2.22 +1.25 11250 98.74%
May 04 408.74 409.49 0.91 -0.75 10843 96.27%
May 31 407.09 405.78 2.88 -1.31 11602 99.81%
June 20 403.30 404.89 1.76 -1.59 10912 97.13%
Aug. 20 402.32 400.00 0.11 +2.32 11597 98.05%
Nov. 21 408.01 408.05 1.13 -0.04 10242 99.52%
Dec. 04 408.15 409.52 0.53 -1.38 10174 96.64%
Average / / /
Validation to ACGS XCO2 using FTS 125HR Measurement
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
Summary
1 In this study, we evaluated the in-flight spectroscopic and
radiometric performanceof the ACGS using measured data from solar
diffuser and halogen tungsten lampdevices.
2 In-flight calibration and validation work of the ACGS has
achieved success, andthe radiometric and spectral performance
specifications have met the missionrequirements.
3 The Ver 2.0 L1 products were released to the world on 1
February
2018(http://satellite.nsmc.org.cn/portalsite/default.aspx).
4 The estimated absolute spectral calibration uncertainty is
less than one-tenth ofthe spectral resolution, and the estimated
radiometric uncertainty is less than 5%in the O2 A-band, WCO2 and
SCO2 band.
5 In February 2018, the NSMC TanSat team completed the research
and softwaredevelopment phase of a full physical inversion
algorithm for XCO2 . The softwarehas since been put into operation,
the initial accuracy verification has beencompleted, and
large-scale batch processing and validation efforts are
underway.
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
-
IntroductionPerformance specifications of the TanSat ACGS
In-flight performance of the TanSat ACGSValidation of ACGS
XCO2
Summary
THANK YOU FOR YOUR ATTENTION!
THANK YOU FOR YOUR ATTENTION!
Yang, Zhongdong etc.: [email protected] In-Flight Performance of the
TanSat Atmospheric Carbon Dioxide Grating Spectrometer
IntroductionPerformance specifications of the TanSat
ACGSIn-flight performance of the TanSat ACGSSpectroscopic
performanceRadiometric performance
Validation of ACGS XCO2Summary