Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 79
Appendix A
Past, Present, and Planned Sensors
Past Sensors
Coastal Zone Color Scanner (CZCS)
Sensor/Satellite Agency Mission Duration Swath Resolution Bands Spectral Coverage (nm)
CZCS NASA (USA) 1978-1986 1,556 km 825 m 6 433-12,500
case of failure and was calibrated using the instrument itself.
Sensor Description:
The light from the lamp was used only to verify instrument
The CZCS was the first satellite sensor devoted to ocean stability with time. The calibration revealed the degradation
color imaging. Out of six spectral bands, four were used of the sensitivity in the visible bands (Evans and Gordon,
primarily for ocean color. These four bands were centered 1994). The vicarious calibration was conducted using post-
at 443, 520, 550, and 670 nm with a 20-nm bandwidth. The launch validation cruises and the chlorophyll time-series
mission goal was to test whether satellite remote sensing from Bermuda.
could be used to identify and quantify suspended and dis-
solved material in the surface ocean. The sensor successfully
Data Availability:
demonstrated that ocean color could be used to quantify chlo-
rophyll and sediment concentrations in the ocean. It provided CZCS data are freely accessible.
the justification for SeaWiFS and MODIS.
Applications:
Calibration:
CZCS data were used to demonstrate the feasibility of
The instrument was calibrated pre-launch. The on-orbit ocean color remote sensing and its application to measuring
calibration was to have been accomplished by a built-in global phytoplankton biomass and productivity. Because of
incandescent light source. The light source was redundant in the limited power, it could operate only a few hours per day.
79
OCR for page 80
80 APPENDIX A
Sea-Viewing Wide Field-of-View Sensor (SeaWiFS)
Sensor/Satellite Agency Mission Duration Swath Resolution Bands Spectral Coverage (nm)
SeaWiFS NASA (USA) 1997-2010 2,806 km 1,100 m 8 402-885
Sensor Description: Data Availability:
Data can be freely and openly accessed.1 Global data are
The SeaWiFS mission was launched by the Orbital
Sciences Corporation in 1997. It was a medium-spectral freely distributed at Level 1 (TOA total radiances in eight
r esolution imaging spectroradiometer operating in the bands), Level 2 (geophysical products such as the spectral
visible to near-infrared spectral range, aboard the polar marine reflectances and the chlorophyll concentration), and
sun-synchronous OrbView-2 (OV-2) satellite. The sensor Level 3 (global gridded products).
collected data in eight spectral bands (see Chapter 4; Table
4.5) from 402 to 885 nm. The instrument tilted ±20 degrees
Applications:
to minimize sun glint.
The NASA Ocean Color Group distributes the following
products, which are used for a large array of applications
Calibration:
described in Chapter 2:
SeaWiFS mission used MOBY water-leaving radiances Radiances at 412, 443, 490, 555, 670 nm; aerosol opti-
for the vicarious calibration and near-monthly lunar looks cal thickness at 865 nm; epsilon of aerosol correction at
to track spectral band degradation over time. The mission 765 and 865 nm; OC4 Chlorophyll a concentration; diffuse
included an extensive calibration/validation program using attenuation coefficient at 490 nm; Angstrom coefficient, 510-
global in situ measurements for product validation. 865 nm; Photosynthetically Active Radiation from the sun
400-700 nm; Normalized Difference Vegetation Index; Land
Reflectance and a SeaWiFS Biosphere product.
1 See http://oceancolor.gsfc.nasa.gov/.
GLI
Sensor/Satellite Agency Launch Date Swath (km) Resolution (m) Bands Spectral Coverage (nm)
GLI/ADEOS II NASDA (Japan) 2002-2003 1,600 250/1,000 36 375-12,500
Sensor Description: Calibration:
The Global Imager (GLI) was launched in 2002 aboard Vicarious calibration was performed. Results of vicari-
ous calibration workshop are available online.2
ADEOS II, which also carried POLDER-2 [Polarization and
Directionality of the Earth’s Reflectances]. GLI is designed
to provide frequent global observations of reflected radiance
Data Availability:
of the ocean, clouds, and land. The sensor has a multi-spec-
Data products are available online.3
tral observation capability with 36 bands and ground reso-
lution of 1 km. Some channels have a resolution of 250 m.
Applications:
Ocean color, water-leaving radiances and aerosols.
2 See http://suzaku.eorc.jaxa.jp/GLI/cal/index.html; accessed October
25, 2010.
3 See http://www.eorc.jaxa.jp.
OCR for page 81
81
APPENDIX A
Current Sensors in Polar Orbit
Moderate Resolution Imaging Spectroradiometer
(MODIS) on TERRA and AQUA
Ocean Color Spectral Coverage
Sensor/Satellite Agency Launch Date Swath Resolution Bands (nm)
MODIS (Terra) NASA (USA) 1999 2,330 250/500/1,000 9 405-14,385
MODIS (Aqua) NASA (USA) 2002 2,330 250/500/1,000 9 405-14,385
Sensor Description: More recently, SeaWiFS imagery also had to be used to
address sensor degradation issues.4
MODIS is a key instrument aboard the Terra (EOS AM)
and Aqua (EOS PM) satellites designed for land, atmosphere,
and ocean observations. Terra’s orbit around Earth is timed Data Availability:
so that it passes from north to south across the equator in the
All data and products (Levels 0-4) are freely available
morning, while Aqua passes south to north over the equator
online5 via network download. Products: Normalized water-
in the afternoon. MODIS-Terra and MODIS-Aqua are view-
leaving radiance at 412, 443, 488, 531, 551, and 667 nm;
ing the entire Earth’s surface every one to two days, acquiring
aerosol optical thickness at 869 nm; epsilon of aerosol cor-
data in 36 spectral bands, or groups of wavelengths.
rection at 748 and 869 nm; diffuse attenuation coefficient at
490 nm; Angstrom coefficient, 531-869 nm; and sea surface
Calibration: temperature.
MODIS is calibrated using a combination of solar and
lunar viewing to track spectral calibration and temporal Applications:
degradation as well as vicarious calibration using in situ
MODIS serves a large array of applications including
observations of water-leaving radiance.
process and climate research and many resource managment
applications.
4 See http://www.opticsinfobase.org/abstract.cfm?uri=ao-44-26-5524.
5 See http://oceancolor.gsfc.nasa.gov/.
MERIS Instrument, on Board the ENVISAT Platform
Sensor/Satellite Agency Launch Date Swath Resolution Bands Spectral Coverage (nm)
MERIS ESA (Europe) 2002 1,150 300/1,200 15 412-900
Sensor Description: 4 × 4 pixel averaging (reduced-resolution products). Global
coverage is obtained in three days (irrespective of clouds
MERIS is an ESA-led mission (Rast and Bézy, 1995;
and sun glint).
Rast et al., 1999). It is a medium resolution imaging spectro-
radiometer operating in the visible to near-infrared spectral
Stability Monitoring:
range, aboard the sun-synchronous ENVISAT platform. It is
set up with 15 spectral bands from 412 to 900 nm. MERIS
Radiometric calibration uses two onboard solar dif-
is a “push-broom” spectrometer, with linear CCD arrays
fusers. Spectralon is a very good reflectant with very
providing spatial sampling in the across-track direction,
well-characterized reflectance characteristics. Spectralon
while the satellite’s motion provides scanning in the along-
is subject to reflectance change over time after cumulative
track direction. The MERIS field of view is 68°5 around
exposure to solar radiance, in particular to ultraviolet expo-
nadir, which gives a swath width of 1,150 km covered by
sure. Because frequent solar views are required to monitor
five identical optical modules (cameras) arranged in a fan
the sensor stability, the degradation of the Spectralon also
shape configuration. The spatial resolution at nadir is 300
must be monitored. Therefore, the first diffuser is used every
m (full resolution products), and is degraded to 1.2 km by a
two weeks for routine calibration, and the second one is used
OCR for page 82
82 APPENDIX A
every three months and therefore tracks possible degradation The higher spatial resolution of MERIS resolves coastal
of the first one. An erbium-doped diffuser is used for spectral features such as plumes and fronts that are not evident in the
calibration. MERIS was launched in May 2002 for an initial coarser resolution of the NASA sensors. The higher spectral
and nominal five-year mission, which has been extended so resolution of MERIS enables more sophisticated algorithms
that operations should continue through 2013. for complex coastal waters. The Naval Research Laboratory
at Stennis Space Center is currently using full resolution
MERIS imagery to support assimilation of satellite-derived
Data Availability:
optics into ocean models that provide forecasts on time scales
Open access. Global data are freely distributed at Level of 24-48 hours. NOAA is now acquiring MERIS high spatial
1 (TOA total radiances in 15 bands), Level 2 (geophysical resolution imagery in near-real time (ca. 12 hours) for U.S.
products such as the spectral marine reflectances and the coastal waters. NOAA’s Center for Coastal Monitoring and
chlorophyll concentration), and Level 3 (global gridded Assessment (CCMA) is using MERIS imagery to assess and
products). forecast coastal and marine ecosystem conditions, including
for harmful algal bloom (HAB) forecasts. During summer
2010, CCMA had operational programs to detect cyanobac-
Applications:
teria and other HAB organisms in Lake Erie, Chesapeake
MERIS radiometric capabilities were set up in the 1990s Bay, and Florida coastal waters. According to NOAA’s Dr.
to meet predefined requirements for ocean color remote Richard Stumpf, the MERIS “red bands” (centered at 620,
sensing (e.g., Gordon, 1987, 1988, 1990, 1997; Antoine 665, 680, and 709 nm) are particularly useful for CCMA
and Morel, 1999). The onboard devices have proven very HAB forecasts. There also is high potential for using these
efficient in maintaining a high radiometric accuracy and red bands as an alternative approach for retrieving chloro-
stability. phyll in coastal waters. Algorithms based on these four bands
With respect to coastal applications, the current MERIS are substantially unaffected by atmospheric correction errors.
instrument has considerable advantages over SeaWiFS, This is particularly important given the complexity of the
MODIS, and VIIRS, given its comparatively high spatial atmospheres over the coastal ocean and inland waters.
resolution and many more spectral bands. No U.S. instru-
ment will have MERIS capabilities for the foreseeable future.
COCTS-CZI
Sensor/Satellite Agency Launch Date Swath Resolution Bands Spectral Coverage (nm)
COCTS-CZI/HY-1B CNSA (China) 2007 1,400/500 250/1100 10/4 402-12,500/433-885
With the exception of the general specifications in the
table above, the committee did not obtain additional infor-
mation on the status or performance of the Chinese Ocean
Colour and Temperature Scanner/Coastal Zone Imager
(COCTS-CZI).
OCM-2
Sensor/Satellite Agency Launch Date Swath Resolution Bands Spectral Coverage (nm)
OCM-2/Oceansat-2 ISRO (India) 2009 1,420 360/4,000 9 400-900
Sensor Description: radiance in the shorter wavelengths due to improved atmo-
spheric corrections. The instrument was designed to provide
OCM-2 was successfully launched in 2009 on board
continuity with the OCM instrument.
ISRO’s OCEANSAT-2 spacecraft. OCM-2 has the same
The OCM-2 sensor has a swath of 1,420 km and similar
design and specifications as OCM with the exception of a
bands to OCM, with two changes: The 765 nm channel has
shift in spectral bands 6 and 7 (Chauhan and Navalgund,
been moved to 740 nm to avoid O2 absorption, and the 670
2009). The original 670 nm band (band 6) has shifted to
nm channel has been replaced by a 620-nm channel for better
620 nm; the 765 nm band (band 7) has shifted to 740 nm to
quantification of suspended sediments. Oceansat-2 has two
avoid oxygen absorption. These improvements are expected
modes of operation: Local Area Coverage (LAC) with 360-
to provide greater accuracy of the normalized water-leaving
OCR for page 83
83
APPENDIX A
m real time transmission, and Global Area Coverage (GAC) of 4-km GAC data products on the Internet after the cal/val
with 4-km onboard recording and playback. GAC data phase of the mission. A Letter of Intent with NASA/NOAA
coverage is between ± 75o latitude covering the full globe in for OCEANSAT-2 data sharing was signed last year.
eight days. The OCM-2 instrument is currently providing
excellent datasets. The instrument has a tilting mechanism
Data Availability:
and the tilt is changed twice per year depending on seasonal-
Open access7 users will be provided with Level 1-B
ity, providing minimum sun glint over Indian waters.
basic radiance products (atmospherically corrected), which
can be displayed using SeaDAS. Level 2 products will con-
Calibration:
sist of chlorophyll-a concentration, Total Suspended Matter
OCM-2 includes a solar and lunar calibration (lunar look (TSM), diffuse attenuation coefficients (Kd-490 nm), and
once every six months) to assess sensor degradation.6 A per- Aerosol Optical Depth (AOD) at 865 nm and Level 3 (weekly
manent cal/val site has been set up in the Lakashadweep Sea, and monthly averages generated on trial basis). Level 1 and 2
and data from an optical buoy are being used for vicarious data are available at a nominal cost directly from the National
calibration of OCM-2 data. Extensive ship campaigns will Remote Sensing Centre (NRSC).
also be organized for validation of geophysical data products. Level 3 products will consist of weekly, monthly, and
The NRSA Data Center (NDC) will carry out dissemination yearly binned products (4 km). An OC-4-type algorithm has
been developed for OCM-2 using bio-optical archived data
collected in the Arabian Sea as well as data from NOMAD.
6 See http://www.ioccg.org/sensors/Navalgund_OCM-2.pdf; accessed
October 22, 2010. 7 http://www.ioccg.org/sensors/Navalgund_OCM-2.pdf; accessed Oc-
tober 22, 2010.
Current Sensors in Geostationary Orbit
Korean COMS-1 GOCI
Sensor/Satellite Agency Launch Date Swath Resolution Bands Spectral Coverage (nm)
GOCI/COMS KARI/KORDI 2010 2,500 500 8 400-865
(S. Korea)
Earth (2)
The Korea Aerospace Research Institute (KARI) devel- Earth
oped and launched a GEO ocean color imager (GOCI) on Sensors
(IRES)
June 26, 2010, that is spectrally similar to the Sea-viewing GOCI
Payload
Wide Field-of-view Sensor (SeaWiFS). GOCI offers 360-m
nadir ground sample distance (GSD; close to the CWI 300 MI
m requirement) with sensor-provided pointing knowledge Payload
of 10 mrad, corresponding to 360-m nadir pointing uncer-
tainty (Faure et al., 2007). While the system (Figure A.1) is
located for Asian seaboard imaging and therefore does not
provide western Contiguous United States (CONUS) coastal
imagery, it should allow sub-diurnal GEO coastal marine
data-efficacy verification.
KARI’s Communication and Ocean Monitoring Satellite
(COMS) on which GOCI is mounted provides telecommuni-
cations as well as GOCI data from a relatively small (2,300
kg) GEO spacecraft. This is less than the mass of larger
(3,200 kg) commercial GEO communications satellites, yet
carries the GOCI instrument that has 78-kg mass, 100-W A-1.eps
power, 1.4 × 0.8 × 0.8 m dimensions (x, y, z; z = nadir), with
2 bitmaps
FIGURE A.1 South Korean COMS-1 satellite with geostationary
data rate dependent on custom-selected GOCI integration ocean color imager (GOCI) and the Asian seaboard viewing area.
time per spectral band (Faure et al., 2007). SOURCE: Faure et al., 2007; used with permission from Astrium.
OCR for page 84
84 APPENDIX A
TABLE A.1 GOCI Spectral Capability.
Central Wavelength SeaWIFS GOCT
(nm) (bandwidth, nm) (bandwidth, nm) Primary Use
412 1(20) 1(20) Yellow substance and turbidity
443 2(20) 2(20) Chlorophyll absorption maximum
490 3(20) 3(20) Chlorophyll and
other pigments absorption, K(490)
510 4(20) Chlorophyll absorption
555 5(20) 4(20) Suspended sediment
660 5(20) Fluorescence base 1, chlorophyll,
suspended sediment
670 6(20) Atmospheric correction
680 6(10) Fluorescence signal, atmospheric
correction
745 7(20) Atmospheric correction,
fluorescence base 2
765 7(40) Atmospheric correction, aerosol
radiance
865 8(40) 8(40) Aerosol optical thickness,
vegetation,
water vapor reference over the ocean
The GOCI spectral capability (Table A.1) is modest, that even GOCI-like data, if located over CONUS, would
with a filter wheel to select one of eight SeaWiFS-like spec- provide coastal data to partially close the existing ocean color
tral bands at a time. Nevertheless, the GOCI provides a case data gap. Therefore, were there a low-cost means (compared
study of the benefits of GEO vs. LEO ocean color sensing to the estimated cost of a GOES-R satellite, for example)
via comparison of GOCI MODIS/SeaWiFS ocean color data. to place such a system in GEO, perhaps NOAA and NASA
The committee believes it likely that NASA will conclude would consider it.
Future Sensors in Polar Orbit
VIIRS on NPP and JPSS 1 & 2
Sensor/Satellite Agency Launch Date Swath Resolution Bands Spectral Coverage (nm)
VIIRS/NPP NOAA (USA) 2011 3,000 370/740 22 402-11,800
VIIRS/JPSS 1&2 NOAA (USA) After 2015 3,000 370/740 22 402-11,800
Sensor Description: Calibration:
The Visible Infrared Imager Radiometer Suite (VIIRS) A single solar diffuser and four lunar calibration looks
is a multi-spectral scanning radiometer scheduled to launch per year if no orbital maneuvers are permitted.
in 2011. VIIRS was designed to provide global observations Initial calibration will utilize matches with MODIS-
of land, ocean, and atmosphere parameters at high temporal Aqua. If resources can be mobilized to fund MOBY, MOBY
resolution (~ daily). It consists of a multi-spectral scanning water-leaving radiances will be incorporated as part of the
radiometer (with 22 bands between 400 and 1,200 nm) with vicarious calibration. The calibration for VIIRS on JPSS is
a swath width of 3,000 km. likely to model the calibration of VIIRS on NPP, although
the details regarding lunar maneuvers and a MOBY-like
approach to vicarious calibration has to be determined.
OCR for page 85
85
APPENDIX A
Data Availability: ments (>15 years) that require the deployment of several
satellites for each mission.
NOAA CLASS facility; open availability.
The first Sentinel-3 should be launched in 2013 (Sentinel
3A), and the second one (3B) in 2017. The OLCI is mostly
Applications: based on the MERIS heritage but with 21 spectral channels
instead of 15 and a fixed 12-degree across-track tilt that aims
Water-leaving radiance and chlorophyll.
to minimize sun glint (1,300-km swath). One satellite can
obtain global coverage within four days; two satellites can
OLCI Instrument on the Sentinel-3 platform do so within two days.
The same principles previously used for MERIS radio-
ESA is currently developing three satellite systems
metric and spectral calibration are used for Sentinel-3/OLCI,
that form part of the Space Component of the European
ensuring a high level of radiometric accuracy and stability.
GMES (Global Monitoring for Environment and Security)
The product suite includes all products already provided
program. The Sentinel-3, one of these missions, carries the
by MERIS plus some advanced products, such as inherent
wide-swath, medium resolution (300 m at nadir) visible
optical properties.
and near-infrared “Ocean Land Colour Instrument” (OLCI)
The Sentinel-3 data policy is dictated by the GMES
spectroradiometer.
data policy, i.e., free and open access to all data. The OLCI
The Sentinel-3 mission is meant to be operational, so it
operational ground segment should be operated by EUMET-
has stringent revisit, coverage, and mission life cycle require-
SAT. Other entities will operate the decentralized “thematic”
ground segment.
S-GLI
Sensor/Satellite Agency Launch Date Swath Resolution Bands Spectral Coverage (nm)
S-GLI/GCOM-C JAXA (Japan) 2014 1,150-1,400 250/1,000 19 375-12,500
Sensor Description: The target for data accuracy of SGLI products is at the
same level for GLI products (Murakami et al., 2006).
The Second-Generation Global Imager (S-GLI) will
be flown as part of the Global Change Observation Mission
for Climate research (GCOM-C) mission. This sensor is a Data Availability:
follow-on to the GLI, a multi-spectral radiometer with 19
Data products expected to be available online.9
wavebands ranging from 375 to 12,500 nm. The 250-m spa-
tial resolution aims at improving coastal ocean and aerosol
observations. Applications:
The S-GLI observations aim to improve our under-
Calibration: standing of climate change mechanisms through long-term
monitoring of aerosols, ocean color, derived phytoplankton
Onboard calibrations will include a solar diffuser, inter-
and clouds, as well as vegetation and temperatures.
nal lamp, lunar look by pitch maneuvers (for visible chan-
nels) and lunar through deep space window (for short wave
channels), and dark current.8 9 See http://www.eorc.jaxa.jp.
8 See http://www.ioccg.org/sensors/SGLI_mission_design_201002.pdf;
accessed October 25, 2010.
OCR for page 86
86 APPENDIX A
COCTS-CZI
Sensor/Satellite Agency Launch Date Swath Resolution Bands Spectral Coverage (nm)
COCTS-CZI/HY-1C/D CNSA (China) 2014 2,900/1,000 250/1,100 10/10 402-12,500/433-885
COCTS-CZI/HY-1E/F CNSA (China) 2017 2,900/1,000 250/1,100 10/4 402-12,500/433-885
With the exception of the general specifications in the
table above, the committee did not obtain additional infor-
mation on the status or performance of the Chinese Ocean
Colour and Temperature Scanner/Coastal Zone Imager
(COCTS-CZI).
PACE and ACE
Sensor/Satellite Agency Launch Date Swath Resolution Bands Spectral Coverage (nm)
PACE NASA (USA) >2019 116.6 degree 1 km 26 spectral bands 350-2,135 nm
(5-nm resolution
350-775 nm)
Sensor Description: Data Availability:
The Pre-Aerosol-Clouds-Ecosystem (PACE) and The data likely will be freely and openly available.
Aerosol-Cloud-Ecosystems (ACE) mission aim to advance
research in ocean biology and biogeochemical cycles.
Applications:
The products derived from these sensors will be applied
Calibration:
to research on the carbon cycle, marine ecosystem, phyto-
The need for direct lunar calibration, a vicarious cali- plankton physiology, near-shore and estuarine processes, and
bration site, and global data for product validation are listed on physical-biological interactions.
among the mission requirements.
