Operation and Calibration Status of GOCI

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2016 GSICS Data & Research Working Groups Meeting @ JAXA, Tsukuba, 29. Feb.

1 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb Operation and Calibration Status of GOCI Seongick CHO Korea Ocean Satellite Center, Korea Institute of Ocean Science and Technology

2 Introduction Ocean Color Radiometry Operation Status CONTENTS GOCI Imagery and Applications In-orbit performance (SNR & MTF) In-Orbit Solar Calibration Radiometric & Calibration Model In-Orbit Calibration Results Concluding Remarks 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

3 Introduction Ocean Color Radiometry GOCI Overview Operation Status CONTENTS GOCI Imagery and Applications In-orbit performance (SNR & MTF) In-Orbit Solar Calibration Radiometric & Calibration Model In-Orbit Calibration Results Concluding Remarks 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

Ocean Color Radiometry To Monitor and Research Ocean

light from Ocean CHL : Chlorophyll Concentration CDOM :

04:16(UTC) 05:16(UTC) 06:16(UTC) Hourly Monitoring of TSS

4 Ocean Color Radiometry To Monitor and Research Ocean Biophysical Phenomena with the observation of visible light from Ocean CHL : Chlorophyll Concentration CDOM : Colored Dissolved Organic Matter TSS : Total Suspended Sediment :16(UTC) 01:16(UTC) 02:16(UTC) 03:16(UTC) 04:16(UTC) 05:16(UTC) 06:16(UTC) Hourly Monitoring of TSS 2016 GSICS Data & Research Working Groups GOCI Meeting JAXA, 3. Tsukuba, Feb. GOCI 2016 CHL_

Ocean Color Radiometry Scientific Definition : the derivation from the top-of-atmosphere radiance at a certain wavelength λ, L T (λ), reaching a space sensor, of the spectral upward radiance, L W

5 Ocean Color Radiometry Scientific Definition : the derivation from the top-of-atmosphere radiance at a certain wavelength λ, L T (λ), reaching a space sensor, of the spectral upward radiance, L W (λ), leaving the water surface in the direction of the sensor (Ref. Jean-François Berthon, et. al., 2008) E D L T E D : Downward Solar Irradiance L T : Top-of-atmosphere Radiance Spectral Response Comparison between L T and L W L w : Water Leaving Radiance (10~20% of L T ) L a : Atmosphere Path Radiance (80~90% of L T ) (Ref. L 2016 r : Surface-Reflected Radiance GSICS Data & Research Working Groups Meeting (Ref. JAXA, Tsukuba, 29. Feb

6 Satellite platform: COMS Meteorological

Satellite (aka Chollian) Developments of

of KOSC (Ground System) : 2005 The first

Launch date : June 27 2010 Lifetime : 7 years

Color Imager (GOCI) Meteorological Imager

6 6 Satellite platform: COMS Meteorological Imager L-band antenna Geostationary Ocean Color Imager Ka-band antenna COMS : Communication, Ocean & Meteorological Satellite (aka Chollian) Developments of COMS(H/W) and GDPS(S/W) : 2003 Establishment of KOSC (Ground System) : 2005 The first Korean Geostationary multipurpose Satellite Launch date : June Lifetime : 7 years Payloads (3 Missions) Geostationary Ocean Color Imager (GOCI) Meteorological Imager Ka-band Communication 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

7 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb COMS geostationary orbit 7

GOCI : Overview Geostationary Ocean Color Imager VIS/NIR Multispectral Imager for Ocean Monitoring GSD(Ground

Pohang-Si, Korea) Temporal Resolution : 1hour (8 times at 1 day) Spectral Bands Characteristics of GOCI Band

turbidity B2 443 nm 20 nm 1,090 Visible Chlorophyll absorption maximum B3 490 nm 20 nm 1,170 Visible

Turbidity, suspended sediment Latitude (deg) P3 (-Y,+Z) 45,00 40,00 35,00 30,00 25,00 20,00 P7 Slot 16 Slot 9

fluorescence signal, Chlorophyll, suspended sediment B6 680 nm 10 nm 870 Visible Atmospheric correction and

fluorescence signal Aerosol optical thickness, vegetation, water vapor reference over the ocean 110,00 115,00

8 GOCI : Overview Geostationary Ocean Color Imager VIS/NIR Multispectral Imager for Ocean Monitoring GSD(Ground Sampling Distance) : 500m@130 E 36 N, ~370m@nadir Target Area : 2,500km * 2,500km (Center : 130 E 36 N; Pohang-Si, Korea) Temporal Resolution : 1hour (8 times at 1 day) Spectral Bands Characteristics of GOCI Band Band Center Band Width SNR Type Primary Application B1 412 nm 20 nm 1,000 Visible Yellow substance and turbidity B2 443 nm 20 nm 1,090 Visible Chlorophyll absorption maximum B3 490 nm 20 nm 1,170 Visible Chlorophyll and other pigments P2 (+Y,+Z) 50,00 Target Area P6 P1 (+Y,-Z) B4 555 nm 20 nm 1,070 Visible Turbidity, suspended sediment Latitude (deg) P3 (-Y,+Z) 45,00 40,00 35,00 30,00 25,00 20,00 P7 Slot 16 Slot 9 Slot 12 Slot 8 Slot 1 P8 Slot 5 Slot 4 Slot 13 P5 P4 (-Y,-Z) B5 660 nm 20 nm 1,010 Visible Baseline of fluorescence signal, Chlorophyll, suspended sediment B6 680 nm 10 nm 870 Visible Atmospheric correction and fluorescence signal B7 745 nm 20 nm 860 NIR B8 865 nm 40 nm 750 NIR Atmospheric correction and baseline of fluorescence signal Aerosol optical thickness, vegetation, water vapor reference over the ocean 110,00 115,00 120,00 125,00 130,00 135,00 140,00 145,00 150,00 Longitude (deg) 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

9 Introduction Ocean Color Radiometry GOCI Overview Operation Status CONTENTS GOCI Imagery and Applications In-orbit performance (SNR & MTF) In-Orbit Solar Calibration Radiometric & Calibration Model In-Orbit Calibration Results Concluding Remarks 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

Tidal effects on turbidity GOCI 2011 년 4 월 16 일 09 10 11 12

10 Tidal effects on turbidity GOCI 2011 년 4 월 16 일 시 30 분획득영상 Yello w Sea Seoul R rs RGB-642 composite image (background : l1b band6) 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

Massive HAB detected by GOCI Massive outbreak of harmful algae (C.

and was expanded to eastern coastal waters in Aug- Sep, 2014.

difficult with in situ observations only.

11 Massive HAB detected by GOCI Massive outbreak of harmful algae (C. polykrikoides) ocurred in the south coast of Korea (red-color patches in GOCI image) and was expanded to eastern coastal waters in Aug- Sep, GOCI image was useful to identify the spatial coverage of the HAB event, which was difficult with in situ observations only. Korean Media reporting that satellite captured a huge red-tide patch in the south coast of Korea in GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb. 2016

12 HAB in 2015 HAB area (2015/08/04~09/14) <2015 년 9 월 11 일 12:15 GOCI 순수해수신호합성영상 (R:B6,G:B4,B:B2)> 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

2016 Floating algae (Sargassum horneri) In

horneri were found in coastal areas of Jeju

GOCI image (bottom-left image) revealed that

and barely visible using contrast in 745nm

13 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb Floating algae (Sargassum horneri) In Jan-Feb 2015, accumulated patches of Sargassum horneri were found in coastal areas of Jeju island and southwest of Korea. GOCI image (bottom-left image) revealed that the floating algae patches were widely spread in the northern East China Sea. Spectral signature of Sargassum patch is weak and barely visible using contrast in 745nm before atmospheric correction.) 22 April 2015 R:745 Enhanced G:660 R745-R555 B:555 Spatial Anomaly of

2016 14 Trouble for Olympics in 2008 14 Qingdao

14 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb Trouble for Olympics in Qingdao sailing venue Boats racing on green meadow?? (Reflectance spectra)

Floating green algae in 2015 <2015 년 5 월

15 Floating green algae in 2015 <2015 년 5 월 25 일 12:15 GOCI 레일레이보정합성영상 (R:B8,B:B7,G:B6)> FA Area (2015/05/16~08/23) <2015 년 5 월 25 일 12:15 GOCI 레일레이보정합성영상 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, (R:B6,B:B4,G:B2)> 29. Feb. 2016

16 Introduction Ocean Color Radiometry GOCI Overview Operation Status CONTENTS GOCI Imagery and Applications In-orbit performance (SNR & MTF) In-Orbit Solar Calibration Radiometric & Calibration Model In-Orbit Calibration Results Concluding Remarks 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

In-Orbit Performance : SNR Assessment Methods for In-Orbit SNR Performance Required Uniform Image for SNR Assessment : SNR ~ Mean/STDEV Method 1: Earth Image Acquisition (Clear

800 1000 1200 1400 200 400 600 800 1000 1200 1400 Acquired Diffuser Image (SD) Spectral Band SNR Requirement Estimated SNR (Earth Image) Estimated SNR (Diffuser Image) Band #1 1077

17 In-Orbit Performance : SNR Assessment Methods for In-Orbit SNR Performance Required Uniform Image for SNR Assessment : SNR ~ Mean/STDEV Method 1: Earth Image Acquisition (Clear Ocean) Method 2: Diffuser Image Acquisition (Solar Diffuser) B5 B6 200 B5 200 B Acquired Earth Image (Clear Ocean) Acquired Diffuser Image (SD) Spectral Band SNR Requirement Estimated SNR (Earth Image) Estimated SNR (Diffuser Image) Band # N/A Band # N/A Band # N/A Band # N/A Band # Band # Band # Band # SNR Comparison between Method 1(Earth) and Method 2 (Diffuser) Band 1 Band 2 Band 3 Band 4 Band 5 Band 6 Band 7 Band GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb SNR Estimated SNR value from imagery GOCI Requirement GOCI SNR MODIS SNR Observational Bands SNR Assessment by Earth Image Acquisition

In-Orbit Performance : MTF Assessment Methods for

(Knife Edge Method) Method 2: PSF (Point Spread

Korea, R: Japan) Acquired Image for PSF [Method 2]

18 In-Orbit Performance : MTF Assessment Methods for In-Orbit MTF Performance (for Band 8) Method 1: KEM (Knife Edge Method) Method 2: PSF (Point Spread Function) Acquired Image for KEM [Method 1] (L : Korea, R: Japan) Acquired Image for PSF [Method 2] Diurnal MTF Variation at Nyquist Freq. Seasonal MTF Variation at Nyquist Freq GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb. 2016

19 Introduction Ocean Color Radiometry GOCI Overview Operation Status CONTENTS GOCI Imagery and Applications In-orbit performance (SNR & MTF) In-Orbit Solar Calibration Radiometric & Calibration Model In-Orbit Calibration Results Concluding Remarks 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

In-Orbit Solar Calibration Solar Calibration using solar diffuser is the baseline method for Radiometric

Monitoring Device) is the second diffuser in GOCI Sun is a reference light source for GOCI in-orbit

radiometric accuracy Because GOCI Solar Diffuser shows variation of transmittance with respect to the

this research Solar Diffuser Open DAMD Shutter wheel SD(Solar Diffuser) DAMD Dim : 14cm Dim : 7cm

20 In-Orbit Solar Calibration Solar Calibration using solar diffuser is the baseline method for Radiometric Calibration of GOCI Subsystem for Solar Calibration : Solar Diffuser & DAMD DAMD(Diffuser Aging Monitoring Device) is the second diffuser in GOCI Sun is a reference light source for GOCI in-orbit calibration Characterization of Diffuser Transmittance with high accuracy is the key to achieve the radiometric accuracy Because GOCI Solar Diffuser shows variation of transmittance with respect to the light incident angle, dedicated characterization model is implemented into calibration S/W developed by this research Solar Diffuser Open DAMD Shutter wheel SD(Solar Diffuser) DAMD Dim : 14cm Dim : 7cm Diffuser for irradiation test (other half one : reference) 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

Calibration Radiance Calculation Solar Irradiance Reference Spectra GOCI Spectral

Thuillier, 2004) Solar Irradiance Sun-Earth Distance Model (Ref.

Radiance Calculation In-Band Instrument Solar Irradiance GOCI Diffuser BTDF Model

1deg rotation in Roll Solar Incident Angle Solar Diffuser BTDF Model Calibration

21 Calibration Radiance Calculation Solar Irradiance Reference Spectra GOCI Spectral Response Function (Ref. Thuillier, 2004) Solar Irradiance Sun-Earth Distance Model (Ref. Spencer, 1971) Sun-Earth Distance Model Instrument Spectral Model Calibration Radiance Calculation In-Band Instrument Solar Irradiance GOCI Diffuser BTDF Model Solar Incident Angle Calculation Orbital Position of Sun Frame Conversion - 5.1deg rotation in Roll Solar Incident Angle Solar Diffuser BTDF Model Calibration Radiance ECEF: Earth Centered Earth Fixed Frame ALOF: AOCS Local Orbital Frame 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

Number), raw data measured from GOCI instrument and radiance L : Spectral Radiance(W/m 2 /um/sr) G, b : Linear & Non-linear Gain T int :

22 Radiometric Model Calibration Radiance Gain Calculation by Radiometric Model Calibration Digital Counts(DC) Radiometric Gains In-Orbit Radiometric Calibration GOCI Radiometric Model : 3 rd -Order Polynomial Mathematical equation to express the relationship between DN(Digital Number), raw data measured from GOCI instrument and radiance L : Spectral Radiance(W/m 2 /um/sr) G, b : Linear & Non-linear Gain T int : Integration Time O, F : dark current parameters Linear Gain (G) Non-linear Gain (b) 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

DN at dark position = O x T + F (Linear Model) O : Dark Signal proportional to integration time & temperature (GOCI dark

23 Pre-Launch Calibration Test Radiometric Test : Offset Correction Sensor background noise shall be corrected before calibration. DN at dark position = O x T + F (Linear Model) O : Dark Signal proportional to integration time & temperature (GOCI dark signal increasing rate = 2 times/8 ) T : Integration time F : Fixed Offset Baseline background noise Dark Image(DN) Evaluation for 10 pixels Fixed Offset (F) Parameter O 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

2016 24 Image Acquisition of GOCI GOCI Image

int. time) GOCI Raw Image (B1-B8) GOCI Local

24 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb Image Acquisition of GOCI GOCI Image Acquisition Sequence GOCI Dark Image (Max int. time) GOCI Raw Image (B1-B8) GOCI Local Area coverage by 16 slots GOCI Dark Image (min int. time)

25 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb Monitoring of In-Orbit Status Trend Monitoring of FPA Temperature The GOCI detector(2d CMOS) includes internal temperature acquisition which are part of the image data and correspond to the first(0) and last columns(1431) of the detector. Temperature of GOCI FPA is stable.

26 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb Monitoring of In-Orbit Status Trend Monitoring of Dark Current * Diurnal Operation error : Increased FEE temperature * Daily Diurnal Trend of Dark Current Parameters(O, F) The averaged O is sensitive to temperature variation of sensor by increasing the integration time. Though integration time is not changed, the diurnal variation is found in fig. 2. (Cf. O 1/F) (max : 03 or 04 UTC, min : 00 and 07 UTC) The pattern of O seems to be related with diurnal solar energy variation. The uptrend shown in fig. 1 is also found in fig. 2. Daily Trend of Dark Current Parameters(O, F) from Aug to Dec Daily mean F and O are about 596±16 and 0.04±0.013 Only, the daily mean O is increasing slightly. But the variation is very small. GOCI detector has been operated in stable

27 Discussion for Gain Evolution (3/3) Evolution of Radiometric Gain (Jan. 2011~May 2015) In 2012, unexpected gain evolution was found. No challenging issue for gain evolution (except for the poor diffuser BSDF characterization with respect to the solar incident angle(az)) After diffuser aging corection using DAMD, assessed annual gain evolution is ~0.2% (2011~2014) and ~0.6% (2015~ ) for mean gain value of 2M pixels GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

Systematic Behavior Correction Solar incident angle effect(az) correction Due to the insufficient characterization of solar diffuser(variation of diffuser transmittance w.r.t. solar incident angle) in pre-launch test, Empirical correction method is in the development.

28 Systematic Behavior Correction Solar incident angle effect(az) correction Due to the insufficient characterization of solar diffuser(variation of diffuser transmittance w.r.t. solar incident angle) in pre-launch test, Empirical correction method is in the development Evolution of Radiometric Gain Before incident angle correction (2013~ ) GSICS Data & Research Evolution Working of Radiometric Groups Gain Meeting After JAXA, angle Tsukuba, correction 29. (2013~ Feb ) 28

Evolution of Defective Pixel Defective pixels determined from Dark Images Dedicated DARK position in Filter Wheel helps to acquire dark images in every slot imaging(32 times/acquisition).

29 Evolution of Defective Pixel Defective pixels determined from Dark Images Dedicated DARK position in Filter Wheel helps to acquire dark images in every slot imaging(32 times/acquisition). From 2011 to 2014, there is very small variation of dark current. (-0.04% after correction of seasonal variation) Defective pixels determined from dark images (same approach in pre-launch test) is increased about 24%. Dark Image(L) & Defective Pixel Map (R) 2016 GSICS Data & Research [2011] Temporal Working Irregular Groups Meeting Pixel to Space JAXA, Environment Tsukuba, 29. Feb

Pixel-level assessment of GAIN Evolution of Radiometric Gain for Each Pixel About 0.4% pixels on 2M(1413 x 1430) CMOS detector have irregular radiometric gain.

30 Pixel-level assessment of GAIN Evolution of Radiometric Gain for Each Pixel About 0.4% pixels on 2M(1413 x 1430) CMOS detector have irregular radiometric gain. Q1 : 1 st quartile Q3 : 3 rd quartile IQR : Interquartile range Definition of Irregular gain pixels : pixel values are below Q1-1.5IQR : or above Q IQR (similar to Box-plot scheme in statistics) Radiometric Gain for BAND 4 # of Irregular gain pxls : 8,023 [ ] 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

gain variability (# of irregular gain pixels : 7,000~89,000) 2016

31 Pixel-level assessment of GAIN Evolution of Radiometric Gain for Each Pixel Annual variation due to solar incident angle(az) derives annual gain variability (# of irregular gain pixels : 7,000~89,000) 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

Residual PRNU Assessment of Residual PRNU On-orbit Quasi-uniform image acquired by daytime diffuser operation for Earth observation Assessed residual PRNU of L1A image B1: 0.28%, B2: 0.

32 Residual PRNU Assessment of Residual PRNU On-orbit Quasi-uniform image acquired by daytime diffuser operation for Earth observation Assessed residual PRNU of L1A image B1: 0.28%, B2: 0.36%, B3: 0.12%, B4: 0.23% B1 B2 On-orbit Quasi-uniform image (GOCI Lv1A, B2) B3 B GSICS Data & Research Working Groups JAXA, Tsukuba, Residual PRNU 29. Feb. assessment

33 Introduction Ocean Color Radiometry GOCI Overview Operation Status CONTENTS GOCI Imagery and Applications In-orbit performance (SNR & MTF) In-Orbit Solar Calibration Radiometric & Calibration Model In-Orbit Calibration Results Concluding Remarks 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

34 Concluding Remarks In-Orbit Calibration of GOCI No blocking point of Mission operation & No critical issue Annual variability of gain & residual radiometric error processing results are planned to be presented in GOCI PI Workshop Lessons for GOCI-II Lunar Calibration for 2 nd solar diffuser aging monitoring Dedicated PRNU correction Diffuser material with Lambertian characteristics Dedicated test campaign for diffuser characterization 2016 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb

35 Tsukuba 감사합니다 GSICS Data & Research Working Groups JAXA, Tsukuba, 29. Feb GOCI L1A True Color RGB

Introduction of GOCI and GOCI-II Mission with Lunar Calibration

Lunar Calibration Workshop, EUMETSAT, 14/12/04 Introduction of GOCI and GOCI-II Mission with Lunar Calibration Seongick CHO Korea Ocean Satellite Center, Korea Institute of Ocean Science and Technology