Geo -stationary Ocean Color Imager (GOCI), Korea Ocean ...learnline.cdu.edu.au/units/ses201/lectures/DBP.pdf · Geostationary satellites: the future of ocean colour remote sensing

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David Blondeau-Patissier

Remote Sensing Group

Purple 12, office 2.26

26 May 2014

Geostationary satellites:

the future of ocean colour remote

sensing at a regional scale

Geo-stationary Ocean Color Imager (GOCI), Korea Ocean Satellite Center (KOSC)

1) Sun-synchronous ocean colour satellites

a. Basic definition and coverage

b. Detecting Chlorophyll-a in East China Sea

2) Geostationary ocean colour satellites

a. GOCI, a Korean pioneer

b. Detecting change in tidal currents,

chlorophyll-a and suspended sediment

3) Conclusion

Content

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Near-polar sun-synchronous orbits:

The old fashion way

Credits : NASA Ocean Biology Processing Group (OBPG)

http://oceancolor.gsfc.nasa.gov/DOCS/SeaDAS/seadas

_training.html

• Near-polar orbits = Orbital plane

crosses the poles and is situated at

high inclination to the Earth's rotation

• low-altitude (700 Km) imaging

• global daily coverage

• Sun-synchronous orbits cross the

equator at the same local time

• Pass over any given latitude at almost

the same local time during each orbital

pass

• Pixel resolution: 1 km ~ 0.3 Km

Swath: 2,330 km 4

Credits : NASA Ocean Biology Processing Group (OBPG)

http://oceancolor.gsfc.nasa.gov/DOCS/SeaDAS/seadas

_training.html

Near-polar sun-synchronous orbits:

MODIS (NASA) Coverage of the Earth in 1 day

MODIS: Moderate Resolution Imaging Spectroradiometer

Source:

Oceanography of Skeletonema costatum harmful algal blooms in the East China Sea using MODIS and QuickSCAT satellite data, Li Shen ;

Huiping Xu ; Xulin Guo ; Ping Wu, J. Appl. Remote Sens. 6(1), 063529 (May 21, 2012).

Chlorophyll-a

4 June 2004 5 June 2004 6 June 2004 7 June 2004 8 June 2004

MODIS (NASA)

Example of daily Chlorophyll-a concentrations

The world’s first geostationary satellite for ocean

colour - GOCI

• Agency: KORDI (Korea)

• On-board COMS satellite

• Launched : 26 June 2010

• Altitude: 36,000 km

• Repeat cycle: 8 images/ day

• Swath: 2,500 km

• Resolution: 500 m

• Hyperspectral : 8 bands

GOCI: Geostationary Ocean Colour Imager

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“Geostationary ocean colour will not be available for at

least another decade”

(IOCCG, 1998)

2010: GOCI has been successfully launched

First image: 13 Jul 2010

“This new way of observing the oceans is likely to generate

unforeseen discoveries or entirely new

ways of processing ocean-colour data.“

(IOCCG, 2012)

The world’s first geostationary satellite for ocean

colour - GOCI

GOCI: example of application

Hourly monitoring of Suspended SedimentEffect of tidal currents in a coastal areas:

• Up to several m/s

• Strong effect on mixing

• Strong effect on sediment load

• Timescale: diurnal

Source: J-H Ryu, KOSC, "GOCI status and GOCI-II plan"

GOCI: example of application

Typhoon and tidal effects

Tides

Typhoon

Sources: Wikipedia; J-H Ryu, KOSC, "GOCI status and GOCI-II plan"

GOCI-II

Taking over the world….

GOCI-II:

• Project has started in 2012

• Launch scheduled in 2018

Challenges and opportunities

Source: Ruddick et al. (2014), Challenges and opportunities for geostationary ocean colour remote sensing of regional seas: A review of recent results, RSE, 146, 63-76.

Sun-synchronous (MODIS, MERIS etc) Geostationary (GOCI)

Launch 1999/2002 - 2010

Temporal resolution Daily to 1 image every 3 days Hourly

Temporal coverage 1.30PM LST equator crossing 8 images per day

Spatial resolution 1 km (up to 300 m with MERIS) 500 m

Spectral resolution 16 bands (visible + NIR) 8 bands (visible + NIR)

Swath ~ 2,000 Km ~ 2,000 Km

Advantages • global applications of near-daily

acquisition of data for the entire earth

from a single sensor

• Well established (for 10+ years,

algorithms are well developed)

• more spectral bands

• Greatly increased temporal

resolution

• Can resolve fast processes

relating to diurnal variability of

biological processes/ tidal …

Challenges • Clouds = still number one problem

• Can’t resolve tidal processes in dynamic

coastal environments ….

• Limited spectral resolution

• No none of the Short Wave

Infrared band necessary for

turbid water atmospheric

corrections…

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Geostationary satellites: the future of ocean

colour remote sensing at a regional scale

David Blondeau-Patissier

Remote Sensing Group

Purple 12, office 2.26

Source: J-H Ryu, KOSC, "GOCI status and GOCI-II plan"

Hyperspectral Ocean colour sensors :

Example of HICO

HICO: Hyperspectral Imager for the Coastal Ocean

• Agency: Office of Naval Research

• On-board International Space Station

• Launched : 18 September 2009

• Altitude: ~ 350 km

• Repeat cycle: limited

• Swath: 50 km

• Resolution: 100 - 500 m

• Hyperspectral : >80 bands, 380 – 900nm

The International Space Station

From “The Hyperspectral Imager for the Coastal Ocean (HICO): Sensor and Data Processing Overview”, by Curtiss O. Davis,

Oregon State University (USA)

Hyperspectral Ocean colour sensors :

Example of HICO – Key Largo, Florida Keys

Chlorophyll-a Attenuation Backscattering

Search Criteria

Time Period: Entire mission (daytime)Sensors: HICO(ISS)

Area of Interest: region bounded by 12.0S and 13.0S and 130.0E and 131.0E

Number of swaths: 21 swaths

Hyperspectral Ocean colour sensors :

Example of HICO – Darwin