In-OrbitObservationofthe SecondGenerationGlobalImager(SGLI ... · Overview of GCOM-C satellite and SGLI 2. GCOM-Coperation status 3. SGLI in-orbit calibration ... SW4 2210 50 1.9

IGARSS 2019August 2, 2019

Japan Aerospace Exploration Agency Yoshihiko Okamura

In-Orbit Observation of theSecond Generation Global Imager (SGLI)

and Study towards Follow-on Imaging Radiometer

Ｙ. Yamada, T. Urabe, S. Ando, K. Tanaka (JAXA)

IGARSS 2019 @Aug. 2 2019

Contents

2

1. Overview of GCOM-C satellite and SGLI2. GCOM-C operation status3. SGLI in-orbit calibration4. SGLI in-orbit observation and products5. Study towards follow-on imaging radiometer6. Summary

IGARSS 2019 @Aug. 2 2019 3

GCOM mission: Long-term observation of the earth’s environment Two satellite series;

GCOM-W “SHIZUKU”: Microwave observation for WATER CYCLEusing AMSR2 (AMSR-E follow on)

GCOM-C “SHIKISAI”: Optical multi-channel observation forRADIATION BUDGET and CARBON CYCLE using SGLI (GLI follow on)

GCOM-C(CLIMATE)

SensorAdvanced MicrowaveRadiometer 2 (AMSR2)

Passive Microwave ObservationWater vapor, soil moisture etc

SensorSecond Generation Global Imager(SGLI)

Optical Observation 380nm – 12 micronCloud, Aerosol, Vegetation, Chlorophyll etc

GCOM-W(WATER)

AMSR2

SGLI

1. Overview of GCOM-C satellite and SGLI(1) Global Change Observation Mission(GCOM)

GCOM-W was launched on May 18, 2012.

GCOM-C was launched on Dec. 23, 2017.

IGARSS 2019 @Aug. 2 2019 4

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

SGLI IRSELU

+ X

flight direction

+Y

+ Z earth

deepspace

SGLI VNRELU

SGLI IRSSRU SGLI VNR

SRU

SGLI Second Generation Global ImagerVNR Visible and Near Infrared RadiometerIRS Infrared Scanning RadiometerSRU Scanning Radiometer UnitELU Electronic Unit

GCOM-C

Orbit Parameters

Orbit Type sun-synchronous, ground track repeat, near-circular orbit

Local sun time 10:15 – 10:45 at descending node

Altitude above equator 798 km at EquatorInclination 98.6 degrees

Mission Life > 5 years

IGARSS 2019 @Aug. 2 2019 5

1. Overview of GCOM-C satellite and SGLI(3) SGLI (Second Generation Global Imager)

PolarizedObservationTelescopes(55deg FOVx 2)

Non PolarizedObservation Telescopes(24deg FOV x 3)

SolarDiffuser

About1.7m

About1.3m

Infrared Scanning Radiometer(SGLI-IRS)

Sun Cal.Window

EarthView Window

DeepSpaceWindow

About1.4m

About0.6m

Sensor Unit featuresSGLI VNR Non Polarized Observation （11ch）, IFOV 250m, Swath 1150km

Polarized Observation（2ch）, IFOV 1km, Swath 1150kmSGLI IRS Shortwave Infrared （SWI 4ch）, IFOV 250m/1km, Swath 1400km

Thermal Infrared （TIR:2ch）, IFOV 500m, Swath 1400km

Visible and Near Infrared Radiometer(SGLI-VNR)

IGARSS 2019 @Aug. 2 2019 6

1. Overview of GCOM-C satellite and SGLI(4) SGLI specifications

SGLI channels

CH

Lstd Lmax SNR at Lstd IFOV

VN, P, SW: nmT: m

VN, P: W/m2/sr/m

T: Kelvin

VN, P, SW: SNR

T: NETm

VN1 380 10 60 210 250 250VN2 412 10 75 250 400 250VN3 443 10 64 400 300 250VN4 490 10 53 120 400 250VN5 530 20 41 350 250 250VN6 565 20 33 90 400 250VN7 673.5 20 23 62 400 250VN8 673.5 20 25 210 250 250VN9 763 12 40 350 1200 250/1000VN10 868.5 20 8 30 400 250VN11 868.5 20 30 300 200 250P1 673.5 20 25 250 250 1000P2 868.5 20 30 300 250 1000

SW1 1050 20 57 248 500 1000SW2 1380 20 8 103 150 1000SW3 1630 200 3 50 57 250SW4 2210 50 1.9 20 211 1000T1 10.8 0.7 300 340 0.2 250/1000T2 12.0 0.7 300 340 0.2 250/1000

The SGLI features are 250m spatial resolution and polarization/along-track slant view channels (VNR-PL), which will improve land, coastal, and aerosol observations.

GCOM-C SGLI characteristics

OrbitSun-synchronous(descending local time: 10:30)Altitude 798km, Inclination 98.6deg

Mission Life 5 years (3 satellites; total 13 years)

Scan Push-broom electric scan (VNR)Wisk-broom mechanical scan (IRS)

Scan width 1150km cross track (VNR: VN & P)1400km cross track (IRS: SW & T)

Digitalization 12bitPolarization 3 polarization angles for PAlong track direction

Nadir for VN, SW and T, +45 deg and -45 deg for P

On-board calibration

VN: Solar diffuser, LED, Lunar calmaneuvers, and dark current by masked pixels and nighttime obs.

SW: Solar diffuser, LED, Lunar, and dark current by deep space window

T: Black body and dark current by deep space window

Multi-angle obs. for 673.5 and 868.5nm

250m over the Land or coastal area, and 1km over offshore

TIR: 500m resolution is also used

IGARSS 2019 @Aug. 2 2019 7

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 movedon to the nominal operation phase on March 28th , 2018

The SGLI initial calibration and validation activities have beencompleted and all the GCOM-C/SGLI products were publicly releasedon December, 2018.

SHIKISAI keeps nominal operations and continuous global observation.

IGARSS 2019 @Aug. 2 2019 8

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 launch

using satellite yaw maneuver.

Tilt Mechanism

Sun

NPTe

le.

Left

NPTe

le.

Cent

erNP

Tele

.Ri

ght

Diffuser DeployMechanismwith safety function

DeployedSpectralon DiffuserLED and Monitor

Bench

Backward TiltingPL telescopes

Tilt Mechanism

NPTe

le.

Left

NPTe

le.

Cent

er

NPTe

le.

Righ

t

PL telescopeTilting Mechanism

Solar CALLED CAL

IGARSS 2019 @Aug. 2 2019 9

3. SGLI in-orbit Calibration(2) IRS Calibration concept

DiffusedSolar Light Deep Space

Earth Observation

BLACKBODY

SCANMIRROR

LightGuide

IRS 81rpm rotating for both “Earth Observation” and “Calibration”.

Light Guide

CalibrationWindow

LightGuide

SpectralonDiffuser

ε > 0.98

BLACKBODY

TIR Calibration : “Black Body” and “Deep Space” SWI Calibration :“Diffused Solar Light”, “LED/Lamp”

and “Deep Space”+Z (Earth)

+Y (Space)

+X (Sat. Velocity)

Halogen Lamp& LED

SCANMIRROR

SWI LED assembly

IGARSS 2019 @Aug. 2 2019 10

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.

Earth Moon

Maneuver

LunarObservation

Calibration interval

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

Lunar phase angle

7deg +/-3deg

SGLI lunar observation

All bands (VNR & IRS)250m resolution

SatelliteManeuver Requirement

- Pitch rate of 0.15 deg/s with high stability- Selectable roll angle (lunar image in SGLI swath)

CT direction: about 29 pixels

AT d

irect

ion:

abo

ut 9

2 lin

es

Pitc

h M

aneu

ver

Lunar calibration data is evaluated using the GSICS lunar calibration tool (GIRO).

IGARSS 2019 @Aug. 2 2019

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

11

0.94

0.96

0.98

1.00

1.02

1.04

1.06

2017/12/23 2018/4/22 2018/8/20 2018/12/18 2019/4/17 2019/8/15

Normalize

d gain tren

d

date

VNR ‐NP (Nadir) Gain TrendLaunch shift using internal lamp calibration (TVT vs 1/10) + Lunar calibration(after 2/1) VN01

VN02

VN03

VN04

VN05

VN06

VN07

VN08

VN09

VN10

VN11

0.94

0.96

0.98

1.00

1.02

1.04

1.06

2017/12/23 2018/4/22 2018/8/20 2018/12/18 2019/4/17 2019/8/15

Normalize

d gain tren

d

date

VNR ‐PL Gain TrendLaunch shift using internal lamp calibration (TVT vs 1/10) + Lunar calibration(after 2/1) P1_0

P1_m60

P1_p60

P2_0

P2_m60

P2_p60

VNR-NP

VNR-PL

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

->Level-1 processing parameters will be modified to keep the radiometric absolute accuracy.

VN06~

VN01

Internal lamp(Launch shift) Lunar calibration (monthly)

Internal lamp(Launch shift) Lunar calibration (monthly)

IGARSS 2019 @Aug. 2 2019

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

12

0.90

0.92

0.94

0.96

0.98

1.00

1.02

1.04

1.06

1.08

1.10

2017

/12/

31

2018

/3/1

2018

/4/3

0

2018

/6/2

9

2018

/8/2

8

2018

/10/

27

2018

/12/

26

2019

/2/2

4

2019

/4/2

5

2019

/6/2

4

2019

/8/2

3

Norm

arize

d ou

tput tren

d

Date

SW1 Gain Trend

Pix1(Solar) Pix2(Solar) Pix3(Solar) Pix4(Solar)Pix5(Solar) Pix1(Halogen) Pix2(Halogen) Pix3(Halogen)Pix4(Halogen) Pix5(Halogen) SW1(Lunar)

Pre‐laun

chIn‐orbit

Solar calibration

Halogen lamp calibration（ratio to SW3）

Lunar calibration

0.90

0.92

0.94

0.96

0.98

1.00

1.02

1.04

1.06

1.08

1.10

2017

/12/

31

2018

/3/1

2018

/4/3

0

2018

/6/2

9

2018

/8/2

8

2018

/10/

27

2018

/12/

26

2019

/2/2

4

2019

/4/2

5

2019

/6/2

4

2019

/8/2

3

Norm

arize

d ou

tput tren

d

Date

SW2 Gain Trend


Pre‐laun

ch

In‐orbit

0.90

0.92

0.94

0.96

0.98

1.00

1.02

1.04

1.06

1.08

1.10

2017

/12/

31

2018

/3/1

2018

/4/3

0

2018

/6/2

9

2018

/8/2

8

2018

/10/

27

2018

/12/

26

2019

/2/2

4

2019

/4/2

5

2019

/6/2

4

2019

/8/2

3

Norm

arize

d ou

tput tren

d

Date

SW4 Gain Trend


Pre‐laun

ch

In‐orbit

Lunar calibration

Solar calibrationHalogen lamp calibration（ratio to SW3）

Lunar calibration

Halogen lamp calibration（ratio to SW3）Solar calibration

0.90

0.92

0.94

0.96

0.98

1.00

1.02

1.04

1.06

1.08

1.10

2017

/12/

31

2018

/3/1

2018

/4/3

0

2018

/6/2

9

2018

/8/2

8

2018

/10/

27

2018

/12/

26

2019

/2/2

4

2019

/4/2

5

2019

/6/2

4

2019

/8/2

3

Norm

arize

d ou

tput tren

d

Date

SW3 Gain Trend

Pix1(Solar) Pix2(Solar) Pix3(Solar) Pix4(Solar)Pix5(Solar) Pix1(LED) Pix2(LED) Pix3(LED)Pix4(LED) Pix5(LED) SW3(Lunar)

Pre‐laun

ch

In‐orbit

Solar calibration

LED calibrationLunar calibration

In-orbit SWIR gain are stable or slightly declining (0~3%) during the 1.5year operation. (Especially SW1 and SW2 bands)

SW1

SW3

SW2

SW4

IGARSS 2019 @Aug. 2 2019 13

4. SGLI in-orbit observation and products

GCOM-C Global Observation

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

2018/09/21 L1B RGB©JAXA

IGARSS 2019 @Aug. 2 2019 14


AreaTop-of-atmosphere (TOA) radianceAtmospheric corrected reflectanceVegetation indexShadow indexFraction of absorbed photosyntheticallyactive radiation (PAR)Leaf area indexAbove-ground biomassVegetation roughness indexLand surface temperatureCloud flag / ClassificationClassified cloud fractionCloud top temperature/heightWater cloud optical thickness /effectiveradiusIce cloud optical thicknessAerosol over the oceanLand aerosol by near ultra violetAerosol by PolarizationNormalized water leaving radianceAtmospheric correction parameterPhotosynthetically available radiatioinChlorophyll-a concentrationSuspended solid concentrationColored dissolved organic matterSea surface temperatureSnow and Ice covered areaOKhotsk sea-ice distributionSnow and ice surface TemperatureSnow grain size of shallow layer

Standard ProductLand

Cryosphere

Atmosphere

Ocean

https://suzaku.eorc.jaxa.jp/GCOM_C/index.html

GCOM-C Products processing <SGLI higher level products>

<SGLI Level1 and Level2 Processing Flow>

Level 1 product (calibrated radiance product) 28 types of higher level products (geophysical

variables)

IGARSS 2019 @Aug. 2 2019 15


SGLI Products (Example)L1B L2

L3 Vegetation indexNDVI

Photosynthetically available radiationPAR

Normalized water leaving radiance

Suspended solid concentration

OKhotsk sea-ice distribution

IGARSS 2019 @Aug. 2 2019 16


Sea Surface Temperature (SST)

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) enables to obtain detailed distribution of geophysical variables.

©JAXA

IGARSS 2019 @Aug. 2 2019 17


Chlorophyll-a Concentration (CHLA)

Under Verification

©JAXA

Chlorophyll-a Concentration around JAPAN (2018/3/14)Distinguishes the detailed phytoplankton distribution.

SGLI capabilities of relatively high spatial resolution (250m) enables to obtain detailed distribution of geophysical variables.

IGARSS 2019 @Aug. 2 2019 18


Land Surface Temperature (LST) ：Intense heat of Japan

Land Surface Temperature (2018/8/1)Daytime temperature is extremely high in big cities such as Tokyo, Nagoya, Osaka.

On the contrary, the daytime temperatures in forest areas are relatively lower.

Under Verification

©JAXA

IGARSS 2019 @Aug. 2 2019


19https://gportal.jaxa.jp/

JAXA G-Portal Website : Data distributionAll the SHIKISAI standard products have been distributed since December 2018.

IGARSS 2019 @Aug. 2 2019

5. Study towards Follow-on Imaging Radiometer

20

JAXA started the concept study of the follow-on mission and imagingradiometer of GCOM-C/SGLI.

Based on the results of the GCOM-C, achievement of furtheroutcomes and social implementation by the GCOM-C data usage areessential for follow-on mission.

Our concept study is focused on the following points;A) Continuous observation to contribute to solve some issues of

climate 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 2019

5. Study towards Follow-on Imaging RadiometerRoadmap for follow-on mission

21

SGLIGLI

VNR (Pushbroom)

IRS (Whiskbroom)1) Compact VNR imagerto enhance the other mission

- High-resolution satellite- LEO observation satellite

2) Infrared mission(Volcano, wild fire, etc.)

<Derived options from SGLI technologies>

<Continuity and Improvement of Climate Change Study>

Follow-on mission

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

Requirement from research

areas

Multi-mission CollaborationSDGs

Future tasks of climate

change study

• 0.38～0.87μm• 13 channels• IFOV: 250m• Polarization and multi-

angle observation

• 1.1~12μm• 6 channels• IFOV: 250m/1km

Improvement based on mission

requirement

・Separate SGLIfunctions・Customize (band and resolution)・Downsize and lightening

User Requirement

Document

Earth Obs. Ground design

(2018)

SGLI Science Community

2002~2003 2017~

IGARSS 2019 @Aug. 2 2019

5. Study towards Follow-on Imaging RadiometerCustomize the SGLI technologies

22

NP optics

PL optics

偏光フィルタ

CCD （6000pixels x 11lines）

11 line bandpass filter

Polarization filter

NP Sub-Unit- 3 telescopes

PL Sub-Unit- 2 telescopes- Tilt mechanism

Optics Filters (bandpass and pol.) Detector

Customize for mission requirementsRealize various missions by combination of SGLI technologies

IGARSS 2019 @Aug. 2 2019

5. Study towards Follow-on Imaging RadiometerGround Resolution Improvement

23

Improvement study of ground resolution using SGLI raw data mode (VN10)

IGARSS 2019 @Aug. 2 2019 24

6. Summary

SHIKISAI keeps nominal operations and continuous globalobservation.

After the SGLI initial calibration and validation activities, allthe GCOM-C/SGLI products (Level-1 products and 28scientific higher level products) were publicly released onDecember, 2018.

JAXA started the concept study of the follow-on mission andimaging radiometer of GCOM-C/SGLI.

IGARSS 2019 @Aug. 2 2019

Acknowledgements

25

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 GIRO implementation agencies led by EUMETSAT and GSICS lunar calibration community for GIRO usage and technical assistance.

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

Coral reefs in the Bahamas Vegetation distribution of the middle of Japan

Morning glow of Kamchatka peninsula 26

©JAXA ©JAXA

©JAXA ©JAXA

Thank you.

Documents

In-OrbitObservationofthe SecondGenerationGlobalImager(SGLI ... · Overview of GCOM-C satellite and SGLI 2. GCOM-Coperation status 3. SGLI in-orbit calibration ... SW4 2210 50 1.9