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.edu2Geosystems Research Institute, Mississippi State University

Stennis Space Center, MS 39529

zplee@ngi.msstate.edu

Davis 2

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 3

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 4

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 5

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 6

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 7

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 8

The Hyperspectral Imager for the Coastal Ocean (HICO)

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

•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)

Davis 9

HICO attached to the JEM-EF on the ISS

HICO Viewing Slit

Davis 10

North

Google Earth

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

HICO Data

Davis 11

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 12

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 13

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 14

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 15

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 16

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 17

Radiometric Comparison of HICO to MODIS (Aqua)

East China Sea off Shanghai

50 km

Image location

Nearly coincident HICO and MODIS images of turbid ocean off Shanghai, China demonstrates that HICO is well-calibrated

HICODate: 18 January 2010Time: 04:40:35 UTC

Solar zenith angle: 53Pixel size: 95 m

MODIS (Aqua)Date: 18 January 2010Time: 05:00:00 UTC

Solar zenith angle: 52Pixel size: 1000 m

Top-Of-Atmosphere Spectral Radiance

R.-R. Li, NRL