JAXA Report‐ GCOM Calibration Plan ‐

Japan Aerospace Exploration Agency (JAXA)

June 2011GSICS Executive Panel, WMO, Geneve

Long‐Term Plan of Earth Observation by JAXA

Targets ~2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

Disasters & Resources

[Optical radiometer]MOS-1, ADEOS

(87~95) (96~97)

[Optical sensor, Synthetic Aperture

Rader]JERS-1 (92~98)

Climate Change

Water Cycle

[Precipitation Rader]PR (97~)

[Microwave radiometer]

MOS-1(87~95)ADEOS2/AMSR(2003

Climate Change

[Optical radiometer]MOS-1, ADEOS

(87~95) (96~97)ADEOS2/GLI

[Cloud profiling radar]

Greenhouse gases

[Spectrometer]ADEOS/ILAS

(96~97)ADEOS2/ILAS2

Phase AOn orbit ExtensionMission status

[Land and Disaster monitoring]

GPM/DPR

Aqua/AMSR-E

GCOM-C1/ SGLI

[Vegetation, aerosol, cloud, SST, ocean color]

[Cloud and Aerosol 3D structure]

[CO2, Methane]

TRMM/PR

GCOM-W1/ AMSR2[Wind, SST , Water vapor]

Phase B~

[Precipitation]

[CO2, Methane]

GCOM-W2

GOSAT-2

ALOS-3 Optical

ALOS-2 SARALOS/PALSAR

ALOS/PRISM AVNIR2ALOS "DAICHI"

EarthCARE/CPR

250m, multi-angle, polarization

GCOM-C2

GOSAT "IBUKI"

TRMM

Aqua

Instrument Second-generation Global Imager

Orbit

Sun Synchronous orbitAltitude：798km (on Equator)Inclination: 98.6 deg.Local sun time: 10:30+/- 15min

Size 4.6m (X) * 16.3m (Y) * 2.8m (Z) (on orbit)

Mass 2093kg

Power gen. More than 4000W (EOL)

Launch JFY 2014 by H-IIA Rocket

Design Life 5-years3

Instrument Advanced Microwave Scanning Radiometer-2

Orbit

Sun Synchronous orbitAltitude：699.6km (on Equator)Inclination: 98.2 degreesLocal sun time: 13:30+/-15 min

Size 5.1m (X) * 17.5m (Y) * 3.4m (Z) (on-orbit)

Mass 1991kg

Power gen. More than 3880W (EOL)

Launch JFY 2011 by H-IIA Rocket

Design Life 5-years

GCOM-W1 (Water) GCOM-C1 (Climate)

• 2 types of medium-sized satellites and 3 generations: 10-15 years observation

GCOM 1st Generation Satellites

Solar calibration window

Earth view windowFOV: 80-deg

Deep space window

Visible and Near-infraredRadiometer(SGLI-VNR)

Non-polarization tree telescopes

Each has the same 11 channels

Solar diffuser

GCOM-Csatellite

Total FOV: 70deg = 24deg 3 telescopes(~1150km@nadir)

Earth direction

Earth

Earth

45deg along-track slant observation

Polarization two (670nm and 865nm) telescopes

Each has tree polarization-angle filters

Scan mortar

Black body

SWIR detector

TIR detectors

Optical bench

Earth

mechanical cooler

Dichroicfilter

TIR detector

SWI detector

Primary mirror

secondary-mirror

Ritchey-Chretien Optics Scan mirror

Incoming light

FOV: 55deg(~1150km@45deg along-track slant)

InfraRed Scanner (SGLI-IRS)

45deg

Internal lamp (PD)

• SGLI initial design and trial manufacturing (breadboard model: BBM) has been done in 2009.• The BBM includes non-polarized and polarized telescopes, spectral filter assembly, mirror scanning

system, detector cooling system, and onboard calibration systems. • The next Engineering Model (EM) manufacturing is under way basing BBM refurbishment, and will

include mechanical vibration and thermal vacuum tests 4

SGLI Instrument: Two Components

Common:• Sensor model: Pre‐launch characterization (gain, diffuser, RSR, polarization..)• Post‐launch functional check: Electric calibration, telemetry monitoring..VNR (push‐bloom type radiometer):• Dark current: optical black (each line), and nighttime observations• Launch shift: LED  diffuser• Short term change: solar light diffuser (~1/week)• Long term change: monthly moon observations by satellite pitch maneuver• Cross check and image quality: vicarious/cross calibration over the CEOS invariant sites• Ocean color adjustment: vicarious calibration at the CEOS instrumented sites (Initial cruises (e.g., TriOS, PRR, SIMBADA..TBD) and long term: MOBY, AERONET‐OC..)

SWIR (scanning radiometer):• Dark current: deep‐space or nighttime observations• Launch shift: LED (a limited band) + halogen lamp (other bands)  diffuser• Short term change: solar light  light guide  diffuser (every path)• Long term change: monthly moon observations by satellite pitch maneuver• Cross check and image quality: vicarious/cross calibration over the CEOS invariant sitesTIR (scanning radiometer):• Dark current: deep‐space and pitch maneuver (around moon calibration) observations• Gain: black body calibration (each scan)• Cross check and image quality: vicarious/cross calibration with SST

SGLI Calibration Strategy

5

6

SGLI On-board Calibration

7

SGLI On-board Calibration

8

GCOM-C observation

Land vegetation, ocean chlorophyll-a,

and primary productionSea and Land surface temperature

Surface albedo and land cover

Surface solar irradiance and Photosynthetically available radiation

Cloud fraction and properties

Aerosol amount and properties

SGLI VNR one-day coverage

Algorithm feedback

Geophysical connection

JPSS/VIIRS

Sentinel-3/ OLCI

synthetic use of the global data

• Global change observation mission• Data merger through sensor cross-calibration and product cross-validation

• Sensor cross-calibration in cooperation with CEOS/WGCV and GSICS.• Product cross-validation in cooperation with CEOS VC and ...

8

Inter-Mission Activity

• Pre-Launch– Measurements of radiometer noise, antenna pattern (main

reflector and CSM), detector non-linearity, sensor alignment, etc.

• Post-Launch– Deep space calibration is scheduled just one time during the

initial checkout phase to assess Main Reflector (MREF) – ColdSky Mirror (CSM) consistency, cold scan bias, and so forth. It willbe implemented by single orbit inertia-lock maneuver over openocean areas.

– Cross calibration with other radiometers and characterizationsuch as scan biases.

– Monitoring of radiometer sensitivity, radiometer gain stability,brightness temperatures at selected stable regions, etc.

– Geometric calibration and determination of sensor alignmentoffsets.

AMSR2 Calibration and Characterization

Page 10

GCOM-W1/AMSR2 characteristics

Scan and rate Conical scan at 40 rpm

Antenna Offset parabola with 2.0m dia.

Swath width 1450km

Incidence angle Nominal 55 degrees

Digitization 12bits

Dynamic range 2.7-340K

Polarization Vertical and horizontal

AMSR2 Channel Set

Center Freq.[GHz]

Band width [MHz]

Pol. Beam width [deg](Ground res. [km])

Sampling interval

[km]

6.925/7.3 350

VandH

1.8 (35 x 62)

1010.65 100 1.2 (24 x 42)18.7 200 0.65 (14 x 22)23.8 400 0.75 (15 x 26)36.5 1000 0.35 (7 x 12)89.0 3000 0.15 (3 x 5) 5

AMSR-EAMSR2

10

Deployable main reflector system with 2.0m diameter.

Frequency channel set is identical to that of AMSR‐E except 7.3GHz channel for helping RFI mitigation.

Two‐point external calibration with the improved HTS (hot‐load).

Deep space calibration maneuver to check consistency between main reflector and CSM.

Add a redundant momentum wheel to increase reliability.

Major Characteristics of AMSR2

• AMSR2 components under proto flight test (PFT): Example of antennapattern measurement of Main Reflector and Feed.

11

AMSR2 Proto-Flight Test

12

Inertia-lockStarts

Inertia-lockEnds

Simultaneous view of deep space by MREF and CSM

Consistency check

Deep space measurement as spatially uniform target

Scan bias identification

MREFView

CSMView

MREFView

CSMView

AMSR2 Deep Space Calibration Maneuver

13

• Inter-sensor calibration with AMSR-E– Participation in the A-Train of GCOM-W1 will provide direct, thus

precise inter-calibration opportunity with AMSR-E.– Propagation of inter-calibration results to previous AMSR-E data

enables to construct reliable long-term dataset.

• Other radiometers– Utilize NWP model output with radiative transfer models to

compensate diurnal difference among polar orbit radiometers. Thiscould potentially done by cooperation with meteorological agencies.Comparison over calm and clear ocean areas for cold end calibration.Inter-calibration over polar regions, where polar orbiting microwave radiometers can shere their observations.Non-sun-synchronous radiometer such as TMI and GMI, as a space-based transfer radiometer.→ GPM cross-calibration concept

AMSR2 Inter-Sensor Calibration

14

GCOM-W1 System in TKSC