In-Orbit Observation of theSecond Generation Global Imager (SGLI)and Study towards Follow-on Imaging Radiometer

IGARSS 2019
August 2, 2019Japan Aerospace Exploration Agency
Yoshihiko Okamura
Ｙ. Yamada, T. Urabe, S. Ando, K. Tanaka (JAXA)Contents

1. Overview of GCOM-C satellite and SGLI
2. GCOM-C operation status
3. SGLI in-orbit calibration
4. SGLI in-orbit observation and products
5. Study towards follow-on imaging radiometer
6. Summary

IGARSS 2019 @Aug. 2 20192

1. Overview of GCOM-C satellite and SGLI(1) Global Change Observation Mission(GCOM) GCOM mission: Long-term observation of the earth’s environment Two satellite series;
 GCOM-W “SHIZUKU”:
Microwave observation for WATER CYCLE
using AMSR2 (AMSR-E follow on)
 GCOM-C “SHIKISAI”:
Opticalmulti-channel
observation
for
RADIATION BUDGET and CARBON CYCLE using SGLI (GLI follow on)

GCOM-C(CLIMATE)AMSR2GCOM-W(WATER)

SGLI

GCOM-W was launchedon May 18, 2012.

Sensor

GCOM-C was launchedon Dec. 23, 2017.

Advanced Microwave
Radiometer 2 (AMSR2)
Passive Microwave Observation
Water vapor, soil moisture etc

Sensor

IGARSS 2019 @Aug. 2 2019

Second Generation Global Imager(SGLI)
Optical Observation 380nm – 12 micron
Cloud, Aerosol, Vegetation, Chlorophyll etc

31. Overview of GCOM-C satellite and SGLI(2) GCOM-C satellite
SGLI VNR
ELU

SGLI IRS
ELU+X
flightdirection+Y
deep
space+ Z earth

SGLI IRSSRU

SGLI VNR
SRU

SGLI
VNR
IRS
SRU
ELU

Second Generation Global Imager
Visible and Near Infrared Radiometer
Infrared Scanning Radiometer
Scanning Radiometer Unit
Electronic Unit

GCOM-C
Orbit
ParametersMission LifeOrbit Type
Local sun timesun-synchronous, ground track repeat, nearcircular orbit
10:15 – 10:45 at descending node

Altitude above equator

798 km at Equator

Inclination

98.6 degrees> 5 years
IGARSS 2019 @Aug. 2 20194

1. Overview of GCOM-C satellite and SGLI(3) SGLI (Second Generation Global Imager)
Non Polarized
Observation Telescopes(24deg FOV x 3)

SolarDiffuser

EarthView Window

Polarized
Observation
Telescopes(55deg FOVx 2)

Sun Cal.
Window

About
1.4m

About
1.3m

About
1.7m

About
0.6m

Infrared Scanning Radiometer(SGLI-IRS)

Visible and Near Infrared Radiometer(SGLI-VNR)
Sensor Unit

DeepSpaceWindowfeatures

SGLI VNR

Non Polarized Observation （11ch）, IFOV 250m, Swath 1150km
Polarized Observation（2ch）, IFOV 1km, Swath 1150km

SGLI IRS

Shortwave Infrared （SWI 4ch）, IFOV 250m/1km, Swath 1400km
Thermal Infrared （TIR:2ch）, IFOV 500m, Swath 1400km
IGARSS 2019 @Aug. 2 20195

1. Overview of GCOM-C satellite and SGLI(4) SGLI specifications
 The SGLI features are 250m spatial resolution and polarization/along-trackslant view channels (VNR-PL), which will improve land, coastal, and aerosol
250m over the Land or coastal
observations.
area, and 1km over offshore
GCOM-C SGLI characteristics
Sun-synchronousOrbit(descending local time: 10:30)
Altitude 798km, Inclination 98.6deg
Mission Life 5 years (3 satellites; total 13 years)
Push-broom electric scan (VNR)
Scan
Wisk-broom mechanical scan (IRS)
1150km cross track (VNR: VN & P)
Scan width
1400km cross track (IRS: SW & T)
Digitalization 12bit
Multi-angle
Polarization 3 polarization angles for P
obs. for673.5 andAlong track Nadir for VN, SW and T,
868.5nmdirection+45 deg and -45 deg for P

On-board
calibration

VN: Solar diffuser, LED, Lunar cal
maneuvers, and dark current bymasked pixels and nighttime obs.
SW: Solar diffuser, LED, Lunar, and darkcurrent by deep space window
T: Black body and dark current by deep
space window

SGLI channels
Lstd
Lmax SNR at Lstd IFOV
VN, P, SW:
VN, P:
VN, P, SW: nm
SNRm
W/m2/sr/m
T: m
T: Kelvin
T: NET380
1060210250
250
412
10752504002504431064400300
2504901053120400250
530
2041350250250565
203390400
250
673.5
202362400
250
673.52025210250
250763
12403501200
250/1000
868.5
20830400
250
868.5
2030300
200
250
673.5
2025250
250
1000
868.5
2030300
250
1000
1050
2057248
500
1000
1380
208103
150
1000
1630
200
35057250
2210
50
1.9202111000
10.80.7300
340
0.2
250/1000
12.00.7300
3400.2
250/1000


CH
VN1
VN2
VN3
VN4
VN5
VN6
VN7
VN8
VN9
VN10
VN11
P1
P2
SW1
SW2
SW3SW4T1T2IGARSS 2019 @Aug. 2 2019



TIR: 500m resolution is also used6

2. GCOM-C operation status GCOM-C “SHIKISAI” was successfully launched on December 23rd,2017.
 After the three-month activities for SGLI in-orbit checkout, we moved
on to the nominal operation phase on March 28th , 2018
 The SGLI initial calibration and validation activities have been
completed and all the GCOM-C/SGLI products were publicly releasedon December, 2018.
 SHIKISAI keeps nominal operations and continuous global observation.

IGARSS 2019 @Aug. 2 20197

3. SGLI in-orbit Calibration(1) VNR Calibration concept Deployable Spectralon diffuser is used for both Solar and LED calibration.
 β angle dependency for solar calibration will be characterized shortly after launchusing satellite yaw maneuver.
LED CAL

Solar CALNP Tele.
Right

NP Tele.
CenterNP Tele.
Left

NP Tele.
RightNP Tele.
CenterTilt Mechanism

NP Tele.
Left

SunTilt Mechanism
Deployed
Spectralon Diffuser

LED and Monitor
BenchDiffuser Deploy
Mechanismwith safety function

Backward Tilting
PL telescopes

IGARSS 2019 @Aug. 2 2019

PL telescopeTilting Mechanism

83. SGLI in-orbit Calibration(2) IRS Calibration concept
 IRS 81rpm rotating for both “Earth Observation” and “Calibration”.
Calibration
Window

Spectralon
Diffuser TIR Calibration : “Black Body” and “Deep Space”
 SWI Calibration :“Diffused Solar Light”, “LED/Lamp”
and “Deep Space”+Z (Earth)

Light
Guide

Earth Observation

SCAN
MIRROR

Light Guide

Diffused
Solar Light+X(Sat. Velocity) +Y(Space)

Deep SpaceSCAN
MIRROR

LightGuide

ε > 0.98

BLACK
BODY

BLACK
BODY
IGARSS 2019 @Aug. 2 2019

Halogen
Lamp& LED

SWI LED assembly

93. SGLI in-orbit Calibration(3) VNR & IRS Lunar Calibration overview
 Moon reflecting solar light is a stable light source as a long term
calibration reference of the optical sensors.
 GCOM-C lunar calibration maneuvers are planned every 29.5 days
during 5 years mission.
 Lunar calibration data is evaluatedusing the GSICS lunar calibration tool(GIRO).

Lunar phaseangle

7deg +/-3deg

SGLI lunar
observation

All bands (VNR & IRS)
250m resolution

SatelliteManeuver
Requirement- Pitch rate of 0.15 deg/s with highstability- Selectable roll angle (lunar imagein SGLI swath)

MoonLunarObservation

ManeuverCT direction: about 29 pixels

IGARSS 2019 @Aug. 2 2019

AT direction: about 92 lines

Every 29.5 days(= synodic period of the moon andthe sun)

Pitch Maneuver

Calibrationinterval

Earth10

3. SGLI in-orbit Calibration(4) VNR gain trend

Normalized gain trend

VNR-NP

VNR ‐NP (Nadir) Gain Trend
Launch shift using internal lamp calibration (TVT vs 1/10) + Lunar calibration(after 2/1)

1.06

VN02

1.04 Internal lamp

VN03

(Launch shift)

VN04

Lunar calibration (monthly)

VN05

1.02

VN06

1.00

VN07
VN08

0.98

VN09

VN06
~
VN01

0.96
0.94
2017/12/23

VNR-PL

Normalized gain trend

VN01

2018/4/22

2018/8/20

2018/12/18
date

2019/4/17

VN10
VN11

2019/8/15

VNR ‐PL Gain Trend
Launch shift using internal lamp calibration (TVT vs 1/10) + Lunar calibration(after 2/1)

P1_0

1.06

P1_m601.04 Internal lamp

P1_p60(Launch shift)

Lunar calibration (monthly)

1.02

In-orbit VNR gain are
gradually declining(0~6%) during 1.5year
operation.
(Especially the shorter
wavelength bands.)

P2_0
P2_m60->Level-1 processing
parameters will be
modified to keep theradiometric absoluteaccuracy.

P2_p60

1.00
0.98
0.96
0.94
2017/12/23

2018/4/22

2018/8/20

2018/12/18
2019/4/17
2019/8/15
dateIGARSS 2019 @Aug. 2 2019

11

1.04
Lunar calibration
LED calibration

0.98

Solar calibration

0.96
Pix3(LED)

Pix4(LED)

Pix5(LED)

SW3(Lunar)

2019/8/23

2019/6/24

1.10

SW4

1.08

In‐orbit2019/8/23

2019/6/24

2019/4/25

2019/2/24

2018/12/26

2018/4/30

DateSW4 Gain Trend

1.06
1.04
Solar calibration

1.02

Halogen lamp calibration（ratio to SW3）

1.00
0.98

Lunar calibration

0.96
0.94

Pix1(Solar)

Pix2(Solar)

Pix3(Solar)

Pix4(Solar)

0.92

Pix5(Solar)

Pix1(Halogen)Pix2(Halogen)Pix3(Halogen)Pix4(Halogen)Pix5(Halogen)SW4(Lunar)

0.90

2019/4/25

2018/3/1

2017/12/31
Pre‐launchDate2019/2/24

Pix4(Solar)

Pix2(LED)

2018/12/26

Pix3(Solar)

Pix1(LED)

2018/10/27

Pix2(Solar)

Pix5(Solar)

2018/8/28

Pix1(Solar)

0.92

2018/6/29

0.94
0.90

Pix3(Halogen)

Date

In-orbit SWIR gain are stable or slightly declining (0~3%) during the
1.5year operation. (EspeciallySW1 and SW2 bands)
IGARSS 2019 @Aug. 2 20192019/8/23

1.06

1.00

Pix4(Solar)

Pix2(Halogen)SW2(Lunar)

2019/8/23

2019/6/24

SW3 Gain Trend

1.02

Pix3(Solar)

Pix1(Halogen)Pix5(Halogen)2019/6/24

In‐orbit

Pix2(Solar)

Pix5(Solar)
Pix4(Halogen)2019/4/25

1.08

Pix1(Solar)

0.92

2019/2/24

SW3

Normarized output trend

1.10

0.94
0.90

2019/4/25

2018/10/27

2018/3/1

2017/12/31
Pre‐launchDate

Solar calibration
Halogen lamp calibration（ratio to SW3）

0.96

2018/12/26

0.92

Pix3(Halogen)

Lunar calibration

0.98

2018/10/27

Pix4(Solar)

Pix2(Halogen)SW1(Lunar)

1.00

2018/10/27

Pix3(Solar)

Pix1(Halogen)Pix5(Halogen)2019/2/24

Pix2(Solar)

Pix5(Solar)
Pix4(Halogen)2018/12/26

Pix1(Solar)

2018/8/28

0.94

2018/6/29

Halogen lamp calibration（ratio to SW3）

2018/4/30

0.96

1.02

2018/8/28

0.98

1.04

2018/8/28

Lunar calibration

1.06

2018/6/29

Solar calibration

1.00

In‐orbit2017/12/31
Pre‐launch

1.02

1.08

SW2 Gain Trend

2018/6/291.04

0.90

Normarized output trend

Normarized output trend

1.06

SW2

2018/4/30

In‐orbit

1.10

2018/3/1

1.08

SW1 Gain Trend

2018/3/1

SW1

2017/12/31
Pre‐launch

1.10

2018/4/30

Normarized output trend

3. SGLI in-orbit Calibration(5) IRS gain trend

124. SGLI in-orbit observation and products
 GCOM-C Global Observation©JAXA
2018/09/21 L1B RGB

SGLI Wide-FOV (VNR：1150km, IRS：1400km)-> Enable to observe once per tow days around mid latitude zone.
IGARSS 2019 @Aug. 2 201913

4. SGLI in-orbit observation and products
 GCOM-C Products processing
 Level 1 product (calibrated radiance product) 28 types of higher level products (geophysicalvariables)<SGLI Level1 and Level2 Processing Flow><SGLI higher level products>
Standard ProductTop-of-atmosphere (TOA) radianceAtmospheric corrected reflectance
Vegetation index
Shadow index
Fraction of absorbed photosynthetically
active radiation (PAR)
Leaf area index
Above-ground biomass
Vegetation roughness index
Land surface temperature
Atmosphere Cloud flag / Classification
Classified cloud fraction
Cloud top temperature/height
Water cloud optical thickness /effectiveradius
Ice cloud optical thickness
Aerosol over the oceanLand aerosol by near ultra violet
Aerosol by Polarization
Ocean
Normalized water leaving radianceAtmospheric correction parameter
Photosynthetically available radiatioin
Chlorophyll-a concentration
Suspended solid concentration
Colored dissolved organic matterSea surface temperature
Cryosphere Snow and Ice covered area
OKhotsk sea-ice distribution
Snow and ice surface Temperature
Snow grain size of shallow layer
AreaLand

IGARSS 2019 @Aug. https://suzaku.eorc.jaxa.jp/GCOM_C/index.html
2 201914

4. SGLI in-orbit observation and products SGLI Products (Example)
L1B

Normalized waterleaving radiance

Suspended solid
concentration

OKhotsk sea-ice
distribution

L2

L3Vegetation index
NDVI

Photosyntheticallyavailable radiation
PARIGARSS 2019 @Aug. 2 201915

4. SGLI in-orbit observation and products
 Sea Surface Temperature (SST)

©JAXA

Under
Verification

Sea Surface Temperature around JAPAN (2018/3/14)
Sea surface temperature image distinguishes the detailed current structure and vortex convection around coastal area.
SGLI capabilities of relatively high spatial resolution(250m)
obtain detailed distribution of geophysical variables.
IGARSS2019 enables@Aug. 2 to201916

4. SGLI in-orbit observation and products
 Chlorophyll-a Concentration (CHLA)©JAXAUnder
Verification

Chlorophyll-a Concentration around JAPAN (2018/3/14)
Distinguishes the detailed phytoplankton distribution.
SGLI capabilities of relatively high spatial resolution(250m)
obtain detailed distribution of geophysical variables.
IGARSS2019 enables@Aug. 2 to201917

4. SGLI in-orbit observation and products Land Surface Temperature (LST) ：Intense heat of Japan
Under
Verification©JAXA

Land Surface Temperature (2018/8/1)
Daytime temperature is extremely high in big cities such as Tokyo, Nagoya, Osaka.
On the contrary, the daytimetemperaturesin forest
IGARSS2019 @Aug.
2 2019areas are relatively lower.

18

4. SGLI in-orbit observation and products
 JAXA G-Portal Website : Data distribution
All the SHIKISAI standard products have been distributed since December 2018.

https://gportal.jaxa.jp/
IGARSS 2019 @Aug. 2 201919

5. Study towards Follow-on Imaging Radiometer JAXA started the concept study of the follow-on mission and imaging
radiometer of GCOM-C/SGLI.
 Based on the results of the GCOM-C, achievement of further
outcomes and social implementation by the GCOM-C data usage are
essential for follow-on mission.
 Our concept study is focused on the following points;A) Continuous observation to contribute to solve some issues ofclimate change, global environment, food supply and so on.
B) Well-balanced combination between selection of observation
function and outcome maximization.
C) Cooperation and synergy between other observation missions.

IGARSS 2019 @Aug. 2 201920

5. Study towards Follow-on Imaging Radiometer
Roadmap for follow-on mission
2002~2003

2017~

GLISGLI(Whiskbroom)• 0.38~12μm• 36 channels• IFOV: 1km(partially 250m)

VNR (Pushbroom)• 0.38～0.87μm• 13 channels• IFOV: 250m
• Polarization and multiangle observation

IRS (Whiskbroom)• 1.1~12μm• 6 channels• IFOV: 250m/1km

Follow-on mission

Improvement
based onmission
requirement<Continuity and Improvement ofClimate Change Study>
Future tasksof climatechange study

Requirementfrom researchareasSDGsMulti-mission
Collaboration

SGLI Science Community
・Separate SGLI
functions・Customize (bandand resolution)
・Downsize andlightening

Earth Obs.
Ground design(2018)

UserRequirement
Document<Derived options from SGLI technologies>
1) Compact VNR imager
to enhance the other mission- High-resolution satellite- LEO observation satellite2) Infrared mission(Volcano, wild fire, etc.)
IGARSS 2019 @Aug. 2 201921

5. Study towards Follow-on Imaging Radiometer
Customize the SGLI technologies
NP Sub-Unit- 3 telescopes

11 line bandpass filter

NP optics

CCD （6000pixels x 11lines）PL optics

PL Sub-Unit- 2 telescopes- Tilt mechanism
Optics

偏光フィルタPolarization filter

Filters (bandpass and pol.)Detector

Customize for mission requirements
Realizemissions
IGARSSvarious
2019 @Aug.
2 2019 by combination of SGLI technologies22

5. Study towards Follow-on Imaging Radiometer
Ground Resolution Improvement

Improvement study of ground resolution using SGLI raw data mode (VN10)IGARSS 2019 @Aug. 2 201923

6. Summary

 SHIKISAI keeps nominal operations and continuous global
observation.
 After the SGLI initial calibration and validation activities, allthe GCOM-C/SGLI products (Level-1 products and 28
scientific higher level products) were publicly released on
December, 2018.
 JAXA started the concept study of the follow-on mission andimaging radiometer of GCOM-C/SGLI.

IGARSS 2019 @Aug. 2 201924

Acknowledgements

 The authors would like to thank SGLI initial calibration team including
NEC Corporation and RESTEC (Remote Sensing Technology Center).
 SGLI Lunar calibration data was evaluated using the GSICS lunar
calibration tool (GIRO: GSICS Implementation of the Robotic Lunar
Observatory). The authors would like to thank the GIROimplementation agencies led by EUMETSAT and GSICS lunar
calibration community for GIRO usage and technical assistance.

IGARSS 2019 @Aug. 2 201925

©JAXA©JAXA
Vegetation distribution of the middle of Japan

Coral reefs in the Bahamas

Thank you.

©JAXA

©JAXA
Namibia coast and Namib desert IGARSS 2019 @Aug. 2 2019

Morning glow of Kamchatka peninsula

26