Workshop on the Data Utilizationof Greenhouse Gases Observing Satellite (GOSAT)“IBUKI”

Outline ofGOSAT Spacecraft and TANSO SensorNovember 5, 2008
Takashi Hamazaki
Project Manager
GOSAT Project TeamJapan Aerospace Exploration Agency-1Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

1. GOSAT OVERVIEWGOSAT is;
The Greenhouse gases Observing SATellite.
A satellite to monitor global distribution of Greenhouse
Gases (GHG);
Carbon dioxide and Methane at 100-1000km spatial scalewith relative accuracy of 0.3-1% (1-4ppm) for CO2
and 0.6-2% (10-34ppb) for CH4

A joint project ofJAXA (Japan Aerospace Exploration Agency),
MOE (Ministry of the Environment) andNIES (National Institute for Environmental Studies).

Scheduled to be launched by Japan’s H-IIA launch vehicle
in early 2009 from Tanegashima Space Center
Recently named as “IBUKI”-2Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

1. GOSAT OVERVIEW
Observation Points

GOSAT
56,000 points,
every 3 days.
Global andfrequent
observation.
singleinstrument.

（By WMO WDCGG）-3Workshop on the Data Utilization of Greenhouse3Gases Observing Satellite November 5,2008

1. GOSAT OVERVIEW

Organization and RolesGOSAT is the joint project of JAXA, MOE (Ministry of theEnvironment) and NIES (National Institute forEnvironmental Studies).
MOE

JAXA

•Sensor Development(Partial Funding Support)•Data use for Policy
Development•Algorithms development•Data use for science•Data processing(L2-4)•Validation

NIES•Sensor development•Satellite development•H-IIA launch•Satellite operation•Data acquisition•Calibration

GOSATScienceTeam•Scientific Advisory-4Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

1. GOSAT OVERVIEWSatellite Characteristics
Size

Mainbody

1.8m x 2.0m x 3.7m
(Wing Span 13.7m)

MassTotal

1,750kgPowerTotal

3.8KW

Life Span

5 years

Orbit

Launchsun synchronous orbit
Local time

13:00+/-0:15(Descending)

Altitude

666km

Inclination

98deg

Re-visit

3 days

Vehicle

H-IIA

Schedule

Jan. 21st, 2009

H-IIA Launch
Vehicle-5Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

GOSAT on orbit-6Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2. MISSION(TANSO) OVERVIEWTANSO=Thermal And Near infrared Sensor
for carbon Observation

TANSO-FTS(Fourier Transform Spectrometer)
TANSO-CAI(Cloud and AerosolImager)-7Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Principle of the Observation
Observing
spectrum

Carbon Dioxide
absorption

Methaneabsorption

SWIRTIR

Atmosphere

Water Vapor absorption

GHGs absorb specific infrared spectrum.
Reflection on the Earth Surface-8Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Principle of the Fourier Transform Interferometer
M1LightSource

M2: moving mirror

detector
Output from detector=interferogram-9Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS
Specifications

GroundPointing
Mechanismand Fore
opticsConfiguration 2-axes pointing mirror (fully redundant) for

ground pointing, calibration and IMC

Pointing

Cross Track (+/-35 deg）
Along Track (+/-20 deg)

Field of view

IFOV =10.5 km
FOV=790 km (scan width)

SpeedFourierTransform
Spectral chSpectrometer

4, 2, 1.1 sec/ 1 Interferogram
1P, 1S2P, 2S3P, 3S

4

Obs. band(micron)0.75-0.78

1.56-1.72

1.92-2.08

5.5-14.3

Resolution(cm-1)

0.2

0.2

0.2

0.2

Detector

SiInGaAs

InGaAs

PC-MCT

Solar Irradiance, Deep Space,
Moon, Diode Laser (1.55 μm, ILS)

Blackbody,Deep
space

Calibration-10Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Spectral coverage of the each band

-11Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTSOperation Mode
Operation mode
Observation
mode Ⅰ

Description

day time

Observation in the short wavelength infrared bands and thermal infrared bandnight time

Observation in the thermal infrared band. Performs blackbody calibration and deep
space calibration

Observation
mode Ⅱ

The operation of thermal infrared observation is suspended and the pointing
mechanism is locked and TANSO-CAI is assumed as set to the All off mode.
(In case of a failure of one of the solar paddles or other similar events)* The observation time is limited to ten minutes per orbit, and the sensor is set to theStandby II mode for the rest of the time.

Specificobserv.
mode

Sunglint
observation

Observation of the sunglint points according to the commands.

Specific points
observation

Observation of the specified points according to the commands.
“Specific points” include lakes, validation sites, ground-based CO2 observatories etc.

Calibration Lunar calibration
mode

Calibration using the moon in the SWIR bands once a year, as necessary. Thiscalibration is performed by rotating GOSAT to point to the moon and orienting thesensor’s FOV toward the moon using the pointing mechanism.

Solar irradiancecalibration

Calibration using the solar irradiance for every orbit when the satellite is in sunlightand the ground surface is in shade. This calibration takes place at rise of the sun.

Instrument function Calibration of the instrument function by irradiating a 1.55 μm wavelength
calibration
semiconductor laser light.
Electricalcalibration

Calibration of the signal processing in the analogue signal processor and beyond, byinputting a reference voltage signal.

-12Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

In-Orbit Operation
Solar Irradiance
Calibration

Extent of the Shortwavelength Infraredobservation
Directionof Flight

Solar Ray
LunarCalibration
Extent of the Thermal
Infrared observation andblackbody and deep
space calibration
Blackbody and deep space calibration are
performed at regular intervals.
-13Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Operation Pattern (1)Footprint
FTS IFOV=10.5 km
CAI IFOV=0.5,
1.5 kmGOSATDistance ExposureCross(sec)track bet. points
pattern
1790 km
4x33260 km
4x35160 km
47110 km
2988 km
1TANSO-CAI SWATH= 900 km

88 - 280 kmAlong TrackCross Track-14Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Operation Pattern (2)Irregular pattern

Regular Observation Pattern(5 points in the cross-track direction)

Specific Points
Observaton Pattern-15Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS
Scene of the PFM Optical performance test-16Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Test Results (Observation Band)- The proportion of the minimum sensitivity to maximum one in each band
band

1results
(%)

2

3

4

PS

PS

PS

93.0

92.2

92.8

85.9

86.8

91.9

46.3(700-1400cm-1)
28.6(1400-1800cm-1)

3

4- The out of band characteristics
band

1

2

out ofband(μm)<0.746>0.787<1.471>2.000<1.812>2.222<5.56>14.29

results(%)<0.1<0.1<0.1<0.1<0.1<0.1<0.1<0.1-17Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Test Results (S/N, Dynamic Range)
S/Nbands

1P
1S
2P
2S
3P
3S
4

Wavelength*(cm-1)

Spectralradiance*(W/cm2/sr/cm-1)

13050 5.5e-7
6200 5.2e-7
5000 3.8e-7
700 280K

result345
246
322257412
287
283* The specification is defined atthese value

Gain and dynamic range
gainHML1P

6.97

7.29

7.30

1S

7.71

7.39

7.39

2P

9.62

8.77

8.77

2S>10>109.793P

8.98

9.02

7.85

3S

8.18

8.64

7.85

4

NA

9.49

NA

* The output voltage when the maximum
radiance(below table) on each gain isobserved.
Gain

Spectral radiance (W/cm2/sr/cm-1)
Band 1

Band 2

Band 3

Band 4H

5.5e-75.2e-73.8e-7NAM

1.8e-6

1.7e-6

1.3e-6340K

L

5.5e-65.2e-6

3.8e-6NA-18Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Test Results (Flatness in IFOV)The proportion of the minimum
output to maximum one in IFOVband AT/CT
1P
1S
2P
2S
3P
3S
4result(%)

AT

95.34

CT

96.48

AT

93.61

CT

95.15

AT

95.69

CT

92.83

AT

92.86

CT

91.75

AT

91.11

CT

90.12

AT

93.46

CT

95.49

AT

84.75

FWHM in IFOV: the range of the incident
angle where the relative output to thepeak is over 0.5 band AT/CT result(mrad)*definition of IFOV
AT
15.51
1P
1S
2P
2S
3P
optical axis

3S
4

CT

15.74

AT

15.49

CT

15.69

AT

14.70

CT

15.66

AT

14.62

CT

14.61

AT

14.67

CT

15.58

AT

14.57

CT

15.54

AT

15.42

CT
80.81
CT14.41-19Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Test Results (Polarization)
Polarization extinction ratio

Polarization sensitivity
Modebands

AT, CT=0 degree

1Specification

result

<34%

24.9%

2

<38%27.9%

3<38%29.3%

1

<34%

19.9%

2

<38%25.3%

3<38%27.0%

1<34%27.4%

2<38%27.4%

3

<38%

29.6%

Polarization Sensitivity=

P-S
P+S

CT= 35degrees

AT= 20degrees

Modebands

AT, CT= 0 1Pdegree 1S2P2S
3P
3S
CT= 351Pdegrees 1S
2P
2S
3P
3S
AT= 201P
degrees 1S
2P
2S
3P
3S

Specificationresult

<3%

0.27%
0.43%
0.25%
0.74%
0.55%
0.45%
1.64%
3.37%
4.11%
5.39%
4.17%
3.34%
0.36%
0.37%
0.36%
0.37%
0.42%
0.53%

-20Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Test Results (Instrument Function)
Instrument function FWHM
band

Band 1

Band 2

Band 3

Band 4polarization

PSPSPS

FWHM(cm-1)

0.367

0.356

0.258

0.257

0.262

0.263

0.246

Overwrite 01IPT-WNres-004-AA-TDL-4p0H-B0200 20071122 022459 B2P
Peak=1.472e+000 FWHM=0.26024 Position=6285.372

1.21Output [n.u.]

0.8

0.6

0.4

0.20-0.2

Example of the interferogram-Band 2

6281

6282

6283

6284

6285

6286

6287

6288

6289

6290

-1

Wavenumber [cm ]-21Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Test Results (Stray Light)(1) The light through the gas cell filled with only CO2 was input into theFOV of FTS.
(2) The strong light source was set around the FOV of FTS.
(3) It was compared that the cases where the strong light source wasturned on and off.
The difference between two cases was under 0.1 %.

The test result of the stray light:
the red line shows the case that the light source was turned off,the blue line shows the case that the light source was turned on.
-22Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.1 TANSO-FTS

Test Results (stability of the sensitivity)-The stability of the sensitivity to the change in the temperature wasmeasured in the thermal and vacuum test.
The output under the high temperature mode was compared to the one
under the nominal temperature mode and the change per degree
was calculated.
-The maximum change of the sensitivity per degree C is 0.365 %and the change of the temperature of the optical bench
where the optics are placed is estimated under 0.5 degree C per one
revolution.
Therefore the change of the sensitivity is under 0.18 %.

the stability of the sensitivity (%) per degree Cband1

2

3

primary

redundant

primary

redundant

primary

redundant

P0.3650.364-0.315-0.310-0.003-0.023S0.1890.196-0.325-0.326-0.101-0.111-23Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.2 TANSO-CAISpecifications

TANSO-CAI is operated together withTANSO-FTS to- detect aerosol spatial distribution andcloud coverage- retrieve scattering spectral characteristics
of aerosol
Observation
Band
(nm)

CenterWavelength
(nm)

IFOV
(km)

FOV
(km)

No. of Pixels(cross track)1372-387

380

0.5

1000

2000

2667-680

678

0.51000

2000

3866-877

870

0.510002000

41560-1640

1620

1.5

750

500

Band
No.

-24Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.2 TANSO-CAI
Operation Mode

Operation mode

Description

Observation mode

Observation of all bands

Calibration
mode

Lunar
calibration

Calibration using the moon and performed once ayear, as necessary. This calibration is performed byrotating GOSAT to point to the moon and orienting
the sensor’s FOV toward the moon simultaneouslywith FTS

Electricalcalibration

Calibration of the signal processing in the analogue
signal processor and beyond, by inputting areference voltage signal

Night time
calibration

Calibration of the offset level in the night time

-25Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.2 TANSO-CAI
Test Results (1)

OBSERVATION WAVELENGTH
band

1

23

4

center
0.37830.67340.87201.6003wavelength(μm) (0.380±0.005) (0.674±0.005) (0.870±0.005) (1.60±0.01)
wavelength
width(μm)

0.018(<0.02)0.015(<0.02)0.014(<0.02)0.086(<0.1)

out of bandcharacteristics(%)

0.02(<0.360)
0.07(>0.400)
0.01(>0.700)

0.27(<0.658)
0.05(>0.692)

0.05(<0.840)
0.03(>0.890)

0.23(<1.53)
0.07(>1.69)-26Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.2 TANSO-CAI
Test Results (2)Band FOV
(deg)

IFOV
(km)

S/N

Polarization
sensitivity

MTF*:CT/AT

Sensitivity
deviation between
pixels**1

72.27 0.497
274.4 0.018(>72.2) (0.5±0.01)(<0.03)0.6627/0.7505(0.203/0.317)

93.8
(>70)

2

72.28 0.497
223.3 0.017(>72.2) (0.5±0.01)(<0.03)0.4394/0.7310(0.203/0.317)

85.7
(>70)

3

231.8 0.024
72.23 0.496(<0.03)(>72.2) (0.5±0.01)

0.2343/0.6957(0.152/0.238)

86.1
(>70)

4

449.1 0.019
60.18 1.494(<0.03)(>60.0) (1.5±0.02)

0.3257/0.4020(0.203/0.317)

92.1
(>70)

The bracketed value are specification.
*MTF is the value at the nadir** the output of the minimum output pixel when the output of the maximum
output pixel is normalized to100.

-27Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

27

2.2 TANSO-CAI
Test Results (3)Dynamic RangegainHM
L

Spectral radiance (W/m2/sr/μm)
band 1band 2band 3band 4

155
208
900

212
445
1254

129
291
777

35
68
201

MTF
band1

2

3

4

CT

AT

CTAT

CTATCTAT

edge

0.619

0.755

0.295

0.623

0.194

0.511

0.294

0.407

center

0.663

0.751

0.439

0.731

0.234

0.696

0.326

0.402

edge

0.661

0.763

0.313

0.641

0.194

0.333

0.257

0.399

-28Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

2.2 TANSO-CAI
Test Results (4)Registration between bandsBandCTAT

edge(-side)

centerEdge(+side)edge(-side)

centerEdge(+side)

1-0.365

0.168

0.516

0.046

-0.028-0.0282-0.144

0.559

0.982

-0.376-0.219-0.098

3000

000

4

0.095

0.125

-0.122-0.006-0.096-0.120*relative value to the band 3-29Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

3. PRE-LAUNCH CALIBRATION
The pre-launch calibration of TANSO was carried out from three points of view:
radiance, geometry and spectral characteristics.
The following items were evaluated as the pre-launch calibration.

FTS

items

equipment used for the evaluation

instrument function-integrated sphere (Ar lamp)-tunable laser

sensitivity-fixed point blackbody andintegrating sphere-blackbody cavity

IFOV(flatness of the sensitivity -collimatorin the pixel)
CAI sensitivity-fixed point blackbody

bandwidth-monochromator and collimator

Registration between bands-collimator-30Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008

Pre-launch calibration
TANSO-FTS
band123

pre-launch

0.92 %

1.65 %

1.64 %

on orbit

3.01 %

3.01 %

3.01 %

total

3.15 %

3.44 %

3.43 %

40.36K-31Workshop on the Data Utilization of Greenhouse Gases Observing Satellite November 5,2008