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					Analysis of GOCI data in Preparation for
              GEO-CAPE

                      Curtiss O. Davis1
                      ZhongPing Lee2
   1COAS,  Oregon State University, Corvallis, OR 97331 USA
                cdavis@coas.oregonstate.edu
   2Geosystems Research Institute, Mississippi State University

              Stennis Space Center, MS 39529
                   zplee@ngi.msstate.edu
     Outline of Presentation



 Proposed GEOCAPE work to begin this
  summer
 GOCI and GOCI data
 HICO and HICO data
 Planned analysis and products
 Summary and conclusions




                                        Davis 2
                      Proposed Activities

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
    to evaluate:
2. Pointing stability requirements,
3. Improvement in measuring coastal dynamics with hourly data,
4. Radiometric sensitivity requirements for imaging early morning and
    late afternoon,
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.


                                                                           Davis 3
                   Korean GOCI on COMS-1



In June 2010 the Korean
  Geostationary Ocean
   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
       daylight hours.
                              GOCI Image for April 12, 2011 from KOSC website



                                                                                Davis 4
     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
       locations.
      LEO sensors use vicarious calibration and can transfer that advantage
       to GOCI
   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
           of day.


                                                                           Davis 5
         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
                                                                                   Davis 6
                Cross Calibration with MERIS

   MERIS continues to operate well and provide stable well calibrated data.
    http://envisat.esa.int/handbooks/meris/
      Operations officially extended to 2014.
      Follow-on sensors planned for Sentinel 3 satellites to extend time series
       for decades.
   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
       correction.




                                                                               Davis 7
    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
Station (ISS)
                                                               Left, HICO, before
                                                              integration into HREP.
                                                              Right red arrow shows
                                                               location of HREP on
                                                                   the JEM-EF.

                                                              HICO is integrated and
                                                                 flown under the
                                                                direction of DoD’s
                                                               Space Test Program
                                                                              Davis 8
HICO attached to the JEM-EF on the ISS




                                 HICO Viewing Slit




                                                     Davis 9
HICO Image of Pusan, South Korea: 11/18/09




                               HICO Data



         Google Earth




                                             Davis 10
                 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.
   http://hico.coas.oregonstate.edu
   Full description of the data and directions for use on the website




                                                                        Davis 11
               Cross Calibration with HICO

   The Hyperspectral Imager for the Coastal Ocean (HICO) operating on the
    International Space Station since September 2009.
   Advantages
      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
        have.
      HICO will be cross-calibrated with MODIS and MERIS.
      HICO will do vicarious calibration using MOBY and SeaPRISMs.



                                                                         Davis 12
                GOCI and HICO data




 HICO image of Han River, 24 September 2010: Left,100 meter
native resolution. Right, binning to 500 meter (GOCI) resolution.
                                                                    Davis 13
         Planned initial GOCI data Analysis

 Collect simultaneous GOCI and HICO data.
     If possible chose images to include sea truth by other GOCI
      investigators.
     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
      available.
     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
      data.
     Compare water leaving radiances and chlorophyll or other
      standard products.
 Ideally collect simultaneous GOCI, HICO and MERIS data with sea
  truth.
 Analysis should provide verification of GOCI Calibration.
     If data supports it suggest possible adjustments to GOCI team.
                                                                  Davis 14
                             Summary

• First GOCI data available
• Initial analysis to include cross
  calibration with MERIS and
  HICO.
• MERIS is a well calibrated stable
  sensor.
• HICO data better for cross-
  calibration with GOCI data.
   • Spectral data binned to
       match GOCI.
   • 92 m GSD can bin to GOCI
       pixels.
• 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



                                                                                        Davis 15
   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.)
                                                                                 Davis 16
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



                Image location




                         50 km



         R.-R. Li, NRL
                                                                      Davis 17

				
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