GOSAT Calibration Activities in 2 Years Japan Aerospace Exploration Agency 1 10th GSICS Executive Panel - Global Space-based Inter-Calibration System, 10th Session of the Executive Panel WMO, Geneva, Room: 8 JURA (8th Floor), 6 to 8 June 2011

GOSAT full-scale model at EXPO2005 (Aichi, Japan) GOSAT satellite at the launch site of Tanegashima Introduction of GOSAT Mission GOSAT is Greenhouse gases Observing SATellite. Monitoring global distribution of Greenhouse Gases from space Target for Carbon dioxide and Methane at km spatial scale with relative accuracy of 1% (4ppm) for CO2 and 2% (34ppb) for CH4 Joint project by JAXA (Japan Aerospace Exploration Agency), NIES (National Institute for Environmental Studies) MOE (Ministry of the Environment) Launch: 23 January 2009 by H2A launch vehicle Mission lifetime: 5 years to

TANSO=Thermal And Near infrared Sensor for carbon Observation GOSAT Satellite and Sensors SizeMain body 3.7 m x 1.8 m x 2.0 m （ Wing Span 13.7m ） MassTotal1750kg PowerTotal3.8 KW (EOL) Life Time5 years Orbitsun synchronous orbit Local time13:00+/-0:15 Altitude666km Inclination98deg Repeat3 days LaunchVehicleH-IIA ScheduleJan TANSO-FTS (Fourier Transform Spectrometer) TANSO-CAI (Cloud and Aerosol Imager)

TANSO-FTS Spectral Coverage 4

TANSO-FTS Specification 5 Ground Pointing Mechanism and Fore optics Configuration2-axes pointing mirror (fully redundant) for ground pointing, calibration and IMC Pointing Cross Track (+/-35 deg ） Along Track (+/-20 deg) Field of viewIFOV =10.5 km FOV=790 km (scan width) (latitude of 30 deg) Fourier Transform Spectrometer Speed4, 2, 1.1 sec/ 1 Interferogram Spectral ch1P, 1S2P, 2S3P, 3S4 Obs. Band[  m] Target gasO2O2 CO 2, CH 4 CO 2 CO 2, CH 4, O 3 Resolution[cm -1 ]0.2 DetectorSiInGaAs PC-MCT CalibrationSolar Irradiance, Deep Space, Moon, Diode Laser (1.55 micron, ILS) Blackbody, Deep space

TANSO-CAI Cloud and Aerosol Image 6 The plume of erupting Grimsvotn volcano in Iceland R=678nm(Band2) G=870nm(Band3) B=380nm(Band1) UV channel of 380nm is useful for aerosol detection colored in yellow. May 22, 2011, at 15:09

Band Observation Band (nm) Center Wavelength (nm) IFOV (km) FOV (km) Num. of Pixels (cross track) TANSO-CAI is operated together with TANSO-FTS to - detect aerosol spatial distribution and - cloud coverage TANSO-CAI Specifications 7 Onboard calibration: Lunar calibration (/year), Nighttime observation (/month)

TANSO operation with FTS and CAI 8 FTS observation pattern with CAI browse image on Jun. 5, 2010 in dayside Grid observationSunglint observation Target observation The GOSAT is in normal operation from April 2009 over 2 years. The CAI observation swath covers the FTS observation points for cloud screening and aerosol correction.

9 L2 (column abundance obtained by each scan) L3 (spatial and temporal average of column abundances) L1A L1B L4A L4B GOSAT Data Processing JAXA -> Sensor, Level1, Calibration NIES -> Level2, 3, 4, Validation

Launch Critical phase Jan. 23 Level 2 (SWIR CO 2 and CH 4 of column averaged density global distribution) to public Level 1 (Observation spectra) to public Initial Checkout Mission life Initial Cal. and Val. Initial function check Normal observation operation ～ Extra Operati on ～ 2014 GOSAT Mission Schedule - : Nov. 2010Level 3 (SWIR CO 2 and CH 4 column averaged density global distribution in monthly mean) to public May 2011Level2 (TIR CO 2 and CH 4 density profile global distribution) to RA PI mid -2011Level 4A (CO 2 and CH 4 flux in 64 global regions) Level 4B (CO 2 and CH 4 global distribution by 3D model) to RA PI 10

GOSAT L2 and L3 Products (FTS SWIR XCO 2, XCH 4, CAI R min ) 11 XCO 2 Apr 2009 XCO 2 Jul 2009 XCO 2 Oct 2009 XCO 2 Jan 2010 XCH 4 Apr 2009 XCH 4 Jul 2009 XCH 4 Oct 2009 XCH 4 Jan 2010 CAI R min Jun 2009 CAI R min Dec 2009

12 CAI Radiometric Accuracy Land, Clear-sky Ocean, Clear-sky Ocean, Cloud Hawaii ocean B1○ B2○○ B3○ B4○○ Land, Clear-sky Ocean, Clear-sky Ocean, Cloud Hawaii ocean B1○ B2○○○○ B3○○○ B4○○ Initial calibration without zero-level correction L+9M calibration with zero-level correction slopeoffset B B B B Vicarious calibration coefficient Results Vicarious calibrated radiance = slope*(radiance after zero-level correction) + offset B2, B3, B4 calibration B1 relative to B3 B2, B3 ・ Ocean, Cloud ・ Land, Clear-sky ・ Ocean, Clear-sky Combined calibration Results by CAI calibration team

CAI Radiometric Sensitivity Trend at Desert Sites 13 Comparison with MODIS reflectance Annual trend at 9 sites Band1Band2Band3Band4 meanstdevmeanstdevmeanstdevmeanstdev Ref2010/Ref Annual change-1.6%-4.0%-1.2%-1.1% Sahara and Rub Al Khali desert sites CAI annual trends Jun.-Dec. at Sahara_6

FTS-SWIR Radiometric Sensitivity Trend at Desert Sites 14 Band 1 degradation is estimated in 2 %. No degradations in Band 2 and 3. Annual trend

ALOS/AVNIR-2 (R/G/B=3/2/1) 0 10 km ©JAXA Railroad Valley field - Nevada/USA –Base-camp: N; W –Height : about 1435m path37 path36 Vicarious Calibration at Railroad Valley 15

Path 37 from West Path 36 from East 19.9deg 19deg 33.0deg 25deg Surface and Profile of Pressure, Temperature, Humidity Surface Spectral Reflectance Surface CO 2 CH 4 BRDF Aerosol Optical Thickness TOA Spectral radiance RRV Field Experiments Deployment 16

Summary of Radiometric Calibrations for FTS-SWIR and CAI in Days from the launch TANSO-FTSCAI B1B2B3B1B2B3B4 Vicarious calibration (vs. pre-launch calibration) June 23-July 4, ±7%-3±7%-4±7%-17%+4%0%-18% June ±7%-2±5%-6±5%-21%-4% -20% Solar diffuser plate (back side) (vs. onboard initial calibration) June %-0.9%-0.4%N/A June % %N/A Sahara %0% -1.6%-4.0%-1.2%-1.1% April-September June-Sep RRV: Absolute Solar diffuser plate: relative (monitoring change with time) Sahara Data: relative (monitoring change with time)

IASI-GOSAT Simultaneous Nadir Overpasses 18 TANSO-FTS/GOSATIASI/METOP-A Spectral range micron micron Spectral resolution0.2 cm cm -1 Local time13:00 Descending09:30 Descending FOV10 km12 km Spacing interval km65 km Launch22 Jan Oct Time: +/- 20 min Location:+/- 50 km Coincidence is restricted to +/ deg. Match-ups are 65 cases in 3 days.

FTS-TIR Correction Derived from IASI SNOs 19 Collaboration with Univ. Wisconsin cm cm cm cm cm -1 Deep space obscuration correction rate is estimated from IASI-GOSAT SNOs. Significant improvement is confirmed in the 15 micron CO 2 region. Coincidences with IASI are located at high latitude, while AIRS at low-middle latitude.

Conclusions GOSAT is normally operated over 2 years and acquires fine absorption spectra in SWIR to TIR regions with cloud/aerosol imager. Radiometric calibration on orbit in 2 years MODIS reflectance for absolute radiance of SWIR and CAI Inter-comparison attempt with other TIR sensors of IASI Vicarious calibration field campaign with in-situ measurements and aircraft over-flight collaborated with NASA OCO-2 research Annual degradation monitoring at uniform desert sites On-going activities Long-term inter-comparison with IASI and AIRS (collaboration with CNES and RA PIs) Long-term trend monitoring at uniform desert sites Continuous operations of lunar calibration and solar diffuser 20