Analysis of GOCI data in Preparation for
Curtiss O. Davis1
1COAS, Oregon State University, Corvallis, OR 97331 USA
2Geosystems Research Institute, Mississippi State University
Stennis Space Center, MS 39529
Outline of Presentation
Proposed GEOCAPE work to begin this
GOCI and GOCI data
HICO and HICO data
Planned analysis and products
Summary and conclusions
In this project we will investigate the feasibility and utility of ocean color
imaging from a GEO platform using imagery data from the first ever
geostationary ocean color sensor. Specifically:
1. Obtain data from the Korean Geostationary Ocean Color Imager
(GOCI) to evaluate its characteristics and calibration and then use it
2. Pointing stability requirements,
3. Improvement in measuring coastal dynamics with hourly data,
4. Radiometric sensitivity requirements for imaging early morning and
5. Improvement of daily or monthly climatology of bio-geophysical
properties with multiple daily scans,
6. Temporal and spatial characteristics of Sun glint, and
7. Atmospheric and oceanic product quality.
Korean GOCI on COMS-1
In June 2010 the Korean
Color Imager (GOCI)
was launched and it is
providing the first ocean
color imagery from
geostationary orbit for a
region around Korea,
Japan and China. GOCI
is a multispectral
instrument imaging the
region hourly during
GOCI Image for April 12, 2011 from KOSC website
Cross-Calibration with LEO Ocean Color Sensors
Advantages of using Low Earth Orbit (LEO) ocean color sensors:
Can match data collection with GOCI coverage
Can match a full scene covering a variety of environments and sea truth
LEO sensors use vicarious calibration and can transfer that advantage
The challenge is to select the best sensor for matchup with GOCI:
Need to match channels to GOCI channels
• Spectrometers easier to match to GOCI filter channels than other
filter channel instruments.
Need to match Ground Sample Distance (GSD) and sampling locations
• Smaller GSD that can be binned to GOCI GSD is a big advantage.
Most LEO sensors in sun-synchronous orbits – one match time of day
• Non sun-synchronous orbit could provide matches at various times
Cross Calibration with LEO Ocean Color Sensors
Comparison of Spectral Channels
SeaWiFS MODIS GOCI HICO MERIS MERIS Application
411nm 412 nm Hyperspectral 412.5 nm CDOM
443 nm 442 nm 443 nm 380 -1000 nm 442.5 nm chlorophyll
487 nm 490 nm at 5.2 nm 490 nm Chl and other pigments
520 nm 530 nm Can match 510 nm turbidity
550 nm 547 nm 555 nm Any GOCI 560 nm Chl, suspended sediments
channel 620 nm Suspended sediments
670 nm 665 nm 660 nm 665 nm Chl absorption
677 nm 680 nm 681.25 nm Chl fluorescence
705 nm Blooms, Red edge
750 746 nm 745 nm 753.75 nm O2 abs. ref., ocean aerosols
Died 760 nm O2 abs.
After 11 775 nm Aerosols, vegetation
years 866 nm 865 nm 865 nm Aerosols over the ocean
In Dec 890 nm Water vapor reference
2010 900 nm Water vapor absorption
Cross Calibration with MERIS
MERIS continues to operate well and provide stable well calibrated data.
Operations officially extended to 2014.
Follow-on sensors planned for Sentinel 3 satellites to extend time series
Reasonable match between MERIS and GOCI channels.
MERIS is a high resolution spectrometer binned to the selected channels.
This approach gives regular channel shape and is more readily matched
to GOCI filter shapes.
Can request MERIS 300 m GSD data to better match the GOCI pixel size.
MERIS is calibrated against BOUSOLLE buoy data.
Provides a calibration of the water leaving radiances.
Calibrates the combination of sensor calibration and atmospheric
The Hyperspectral Imager for the Coastal Ocean (HICO)
• HICO is an experiment to see what we gain by imaging the costal ocean at
higher resolution from space.
• The HICO sensor:
• first spaceborne imaging spectrometer designed to sample coastal oceans
• samples coastal regions at <100 m (380 to 1000 nm: at 5.7 nm bandwidth)
• has high signal-to-noise ratio to resolve the complexity of the coastal ocean
• Sponsored as an Innovative Naval Prototype (INP) of Office of Naval Research
- built and delivered in 16 months.
• Supported by the Space Test Program for Integration and Launch
• Additional support from NASA and JAXA for launch and integration onto the
Japanese Experiment Module Exposed Facility on the International Space
Left, HICO, before
integration into HREP.
Right red arrow shows
location of HREP on
HICO is integrated and
flown under the
direction of DoD’s
Space Test Program
HICO attached to the JEM-EF on the ISS
HICO Viewing Slit
HICO Image of Pusan, South Korea: 11/18/09
HICO Data Distribution at OSU
Developed HICO Public Website at OSU using published and approved
for distribution data, publications and presentations.
Includes example HICO data.
OSU HICO Web site will be portal for data requests and distribution
Data requests require a short proposal and data agreement signed by
the requestor and their institution and approved by NRL.
Example data and data requested by that user will be available to them.
Full description of the data and directions for use on the website
Cross Calibration with HICO
The Hyperspectral Imager for the Coastal Ocean (HICO) operating on the
International Space Station since September 2009.
HICO is an imaging spectrometer can directly match GOCI channels.
HICO has 100 m GSD; can bin pixels to accurately match GOCI pixels.
HICO on ISS 52 deg. orbit - not sun-synchronous.
• Image at all times of day to match GOCI.
• Look at changes in phytoplankton, chlorophyll, fluorescence and
CDOM production as a function of time of day.
Disadvantage - HICO is a new sensor launched in September 2009.
HICO does not have the calibration history that MODIS and MERIS
HICO will be cross-calibrated with MODIS and MERIS.
HICO will do vicarious calibration using MOBY and SeaPRISMs.
GOCI and HICO data
HICO image of Han River, 24 September 2010: Left,100 meter
native resolution. Right, binning to 500 meter (GOCI) resolution.
Planned initial GOCI data Analysis
Collect simultaneous GOCI and HICO data.
If possible chose images to include sea truth by other GOCI
Remap HIOC data and calculate channels to match GOCI data.
Compare water leaving radiances and chlorophyll or other
standard products, including comparisons with sea truth where
Analyze time series and look for changes with time of day.
Collect simultaneous MERIS 300 m and GOCI data.
Remap MERIS data and calculate channels to match GOCI
Compare water leaving radiances and chlorophyll or other
Ideally collect simultaneous GOCI, HICO and MERIS data with sea
Analysis should provide verification of GOCI Calibration.
If data supports it suggest possible adjustments to GOCI team.
• First GOCI data available
• Initial analysis to include cross
calibration with MERIS and
• MERIS is a well calibrated stable
• HICO data better for cross-
calibration with GOCI data.
• Spectral data binned to
• 92 m GSD can bin to GOCI
• Looking forward to analyzing
GOCI data over the next year to
assess the advantages of
Geostationary data in
preparation for GEOCAPE GOCI Image for April 12, 2011 from KOSC website
Chlorophyll Comparison of HICO to MODIS (Aqua)
Nearly coincident MODIS and HICOTM images of the Yangtze River, China taken on
January 18, 2010. Left, MODIS image (0500 GMT) of Chlorophyll-a Concentration
(mg/m3) standard product from GSFC. The box indicates the location of the HICO image
relative to the MODIS image. Right, HICOTM image (0440 GMT) of Chlorophyll-a
Concentration (mg/m3) from HICOTM data using ATREM atmospheric correction and a
standard chlorophyll algorithm. (Preliminary Results by R-R Li and B-C Gao.)
Radiometric Comparison of HICO to MODIS (Aqua)
Nearly coincident HICO and MODIS images of turbid ocean off
Shanghai, China demonstrates that HICO is well-calibrated
HICO MODIS (Aqua)
Date: 18 January 2010 Date: 18 January 2010
Time: 04:40:35 UTC Time: 05:00:00 UTC
Solar zenith angle: 53 Solar zenith angle: 52
Pixel size: 95 m Pixel size: 1000 m
East China Sea off Shanghai Top-Of-Atmosphere Spectral Radiance
R.-R. Li, NRL