Keiji Imaoka Earth Observation Research Center (EORC) Japan Aerospace Exploration Agency (JAXA)

GSICS/GRWG Meeting Delhi, India (remote participation) March 17, 2015 JAXA Satellite Projects Late 1990s 2000s 2003 (JAXA established)

Earth Observation Climate Change/Water

ADEOS GPM/DPR

EarthCARE/ ADEOS-Ⅱ GCOM-W GCOM-C CPR

Launched on February 28, 2014 (JST) TRMM/PR Aqua/ GOSAT AMSR-E Global Warming GOSAT-2

Land Use

Disaster ALOS Monitoring ALOS-2 Next Gene. Communications (optical) Launched on May 24, 2014 (JST) COMETS DRTS WINDS

Technology Positioning QZSS Development

ETS-Ⅵ ETS-Ⅶ OICETS ETS-Ⅷ 2 GPM

GPM Core Observatory ¢ GPM is an international mission consisting of the GPM Core Observatory and GMI Constellation Satellites for high accurate and (Microwave Imager) frequent global precipitation observation. ¢ Core Observatory: developed under NASA KuPR: and JAXA equal partnership. 13.6GHz ¢ Constellation satellites: provided by radar (phased international partners (includes GCOM-W1). KaPR: 35.5GHz array) radar (phased ¢ Dual-frequency Precipitation Radar (DPR) array) ¢ developed by JAXA and NICT Constellation ¢ DPR is composed of two radars: KuPR & Satellites by KaPR international partners ¢ GPM Core Observatory was successfully launched on 28 Feb. 2014 (JST).

Core Observatory by NASA -JAXA

3 Concept of DPR Calibration

The calibration of DPR is divided by ‘Internal calibration’ and ‘External calibration’ Radio Frequency is not tramsmited to out of DPR Internal Cal. 【Purpose 】 To calibrate the FCIF- LUT which converts digital count to power.

【Frequency 】 Per a week on board.

External Cal. 【Frequency 】 【Purpose 】 External calibration will be To calibrate the planed 10 times in a year. During check out phase, the absolute value of the ★ calibration have been conducted DPR transmitted / 10 times a month at JAXA received powers. tsukuba space center in Japan. FCIF: Frequency Converter & IF 4 Concept of DPR External Calibration

DPR receiver system DPR transmitter system DPR DPR Observed received power Compare Estimated received power Estimated transmitted power Compare Observed transmitted power KaARC KuARC KaARC KuARC To calibrate the received power and the transmitted power of DPR, the difference between observed power and estimated power is evaluated. 5 Active Radar Calibrator

Active Radar Calibrator (ARC) The situation of external calibration At JAXA tsukuba space center

KaARC Calibrator for the ARC KuARC

6 Results of External Calibration Ku Receiver system Ku Transmitter system

average = -0.77dB

Difference observedof powerDifference – estimated power [dB] observedof powerDifference – estimated power [dB] average = +0.19dB

Ka Receiver system Ka Transmitter system Ka Transmit system Difference observedof powerDifference – estimated power [dB] Difference observedof powerDifference – estimated power [dB] average = +1.22dB average = +1.01dB

‹ Although the trends have some offsets, these are stable. JAXA will research for these offsets. ‹ Since the current calibration coefficient satisfies continuity of sigma^0 in DPR L2 from TRMM/PR (not shown), gain offsets found in external calibration has not been adapted now. 7 Intercomparison Oceanic σ0

Comparison with reference to the TRMM/PR Monthly mean & SD Monthly Mean[dB] Monthly

Incidence angle [deg] 8 GCOM 1st Generation Satellites • 2 types of medium-sized satellites and 3 generations: 10-15 years observation “SHIZUKU”

GCOM-W1 (Water) GCOM-C1 (Climate) Instrument Advanced Microwave Scanning Radiometer-2 Instrument Second-generation Global Imager Sun Synchronous orbit Sun Synchronous orbit Altitude ：699.6km (on Equator) Altitude ：798km (on Equator) Orbit Orbit Inclination: 98.2 degrees Inclination: 98.6 deg. Local sun time: 13:30+/-15 min Local sun time: 10:30+/- 15min Size 5.1m (X) * 17.5m (Y) * 3.4m (Z) (on-orbit) Size 4.6m (X) * 16.3m (Y) * 2.8m (Z) (on orbit) Mass 1991kg Mass 2093kg Power gen. More than 3880W (EOL) Power gen. More than 4000W (EOL) Launch May 18, 2012 Launch JFY 2016 Design Life 5-years Design Life 5-years 9

SGLI on GCOM-C

Non Polarized Solar Observation Telescopes Diffuser (24deg FOV x 3) Earth View Window Polarized Observation Telescopes Sun Cal. (55deg FOV Window x 2)

About 1.4m

Deep Space About About About Window 1.3m 1.7m 0.6m

Visible and Near Infrared Radiometer Infrared Scanning Radiometer (SGLI-VNR) (SGLI-IRS)

Sensor Unit features 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 10 SGLI calibration (radiometric)

Sensor component VNR (push-bloom) SWIR (scanning) TIR (scanning)

Calibration target Pre-launch Gain (radiometric sensor model), diffuser, RSR, linearity, Gain, blackbody, RSR, characterization polarization, MTF (PSF), .. linearity.. Functional check Electric calibration, sensor telemetry monitoring.. Optical black (every line), Deep-space or Deep-space and pitch Offset and nighttime observations nighttime observations maneuver observations LED to check change of halogen lamp (+LED) to Launch shift diffuser check diffuser change Black body calibration solar light → diffuser solar light → light guide Short term gain change (~once/week) → diffuser (every path) Monthly Moon (7 °) observations by pitch maneuver for Long term change evaluation of the diffuser degradation ( with GSICS ) Primary source Vicarious calibration over the Vicarious calibration at Vicarious adjustment CEOS instrumented sites and the CEOS instrumented Vicarious/cross ocean cruises sites (land) calibration by SST Vicarious & cross calibration over the CEOS invariant Cross check and image sites (Libya, Dome-C, TuzGolu..), stray light by moon, quality pol sensitivity by simultaneous VNR-PL..

These tasks will be led by the joint team of the JAXA GCOM-C hardware development and data-analysis & application groups 11

SGLI Lunar Calibration

‹ 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 to be conducted every 29.5 days during 5 years mission. ‹ Lunar calibration concept is similar to SeaWiFS.

Earth Moon Lunar Observation

Calibration Every 29.5 days interval (= synodic period of the moon and Maneuver the sun) Lunar phase 7deg +/-3deg CT direction: about 29 pixels angle SGLI lunar All bands (VNR & IRS) observation 250m resolution Satellite - Pitch rate of 0.15 deg/s with high Maneuver stability Requirement - Selectable roll angle (lunar image in SGLI swath) Pitch Maneuver Pitch

AT direction: about 92 lines 92 about direction: AT 12 13 13 14 14 15 15 16 16 MWR for Intercomparison TMI AMSR-E AMSR2 GMI (TRMM) (Aqua) (GCOM-W) (GPM) Launch Year 1997 2002 2012 2014

Sensor appearance

10.65 V/H 10.65 V/H 10.65 V/H 10.65 V/H 19.35 V/H 18.7 V/H 18.7 V/H 18.7 V/H Channels for Intercalibration 21.3 V 23.8 V 23.8 V 23.8 V 36.5 V/H 36.5 V/H 36.5 V/H 36.64 V/H 85.5 V/H 89.0 V/H 89.0 V/H 89.0 V/H Approximate 53.4 * 55.0 55.0 incidence angle 52.8 [degree] (after boost) 54.5 for 89B 54.5 for 89B IFOV at 36GHz [km] 16*9 14*8 12*7 16*9

* Recent information on TMI incidence angle through GPM X-CAL team: Incidence angles at 10V, 10H, and 37V are differ from the base value about 0.65, 0.22, and 0.12 degrees, respectively. Photo of TMI and GMI by NASA 17 Overview of Intercomparison

2rpm Direct Comparison AMSR-E AMSR2 Past data comparison Polar Polar DD-DD MWR Double Double Double MWR Difference Difference Difference

Double Double Difference Difference TMI GMI Double Difference

Non-Sun-Synchronous Orbit 18 Intercomparison Summary

19 Intercomparison Summary

20 Thank you

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