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5
Advancing Global Ocean Color
Remote Sensing into the Future
O
ENHANCEMENTS FOR THE FUTURE
cean color observations from satellites are the princi-
pal tool for the synoptic global monitoring of marine
Advancing Ocean Biology and Biogeochemistry
ecosystems. It is imperative that ocean color obser-
Research
vations are sustained and enhanced into the future. These
observations serve the expanding needs of the scientific
In 2007, the ocean biology and biogeochemistry research
user community as it seeks to understand long-term trends
community completed a consensus document that laid out
in marine ecosystems and their interactions with the global
four priority science questions for the NASA Ocean Biol-
carbon cycle. In turn, managers apply this new knowledge to
ogy and Biogeochemistry program (NASA, 2007). These
value and manage marine resources. This means that future
questions are:
sensors and algorithms need to be enhanced to support an
increasing diversity of ocean color products and applications.
• How are ocean ecosystems and the biodiversity they
However, creating long time-series remains a major chal-
support influenced by climate and environmental variability
lenge, one that is not unique to ocean color remote sensing
and change, and how will these changes occur over time?
(NRC, 2004b, 2008b). These challenges and approaches
• How do carbon and other elements transition between
for sustaining long-term ocean color remote sensing are
various reservoirs in the ocean and Earth system, and how do
explored in this chapter. The key requirements include plan-
biogeochemical fluxes impact the ocean and Earth’s climate
ning to ensure continuity and overlap among sensors; build-
over time?
ing and maintaining the human capital to process, reprocess,
• How (and why) is the diversity and geographical
and use ocean color products for research; and building
distribution of coastal marine habitats changing, and what
international coordination and cooperation.
are the implications for the well-being of human society?
Although the study task focuses on data continuity, it
• How do hazards and pollutants impact the hydrogra-
is important to note that continuity and advancements in the
phy and biology of the coastal zone? How do they affect us,
science require far more than simply sustaining SeaWiFS/
and can we mitigate their effects?
MODIS-type measurements. Many applications listed in
Chapter 2 require more advanced remote sensing capabili-
The implementation strategy calls for a mix of new
ties. This chapter, therefore, explores options for enhancing
sensors including:
ocean color research products. In addition, the U.S. academic
research community, which is primarily funded by National
1. a global hyperspectral imager that would be an
Aeronautics and Space Administration (NASA), needs ocean
advanced Type 1/Type 2 sensor with capabilities as envi-
color instruments such as Aerosol-Cloud-Ecosystems (ACE)
sioned for ACE and PACE;
and the Pre-Aerosol-Clouds-Ecosystems (PACE) for new
2. a Multi-Spectral High Spatial Resolution Imager
and improved applications such as those described in a recent
similar to Hyperspectral Infrared Imager (HyspIRI);
NASA report and summarized below.
3. an ocean color sensor in geostationary orbit to focus
on coastal and ocean processes that require multiple obser-
vations during a single day to resolve changes on short time
scales (like Geostationary Coastal and Air Pollution Events
[GEOCAPE]); and
58
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59
ADVANCING GLOBAL OCEAN COLOR REMOTE SENSING INTO THE FUTURE
Multi-Spectral High Spatial Resolution Imaging
4. a space-borne LIght Detection And Ranging (LIDAR)
for improved atmospheric correction and oceanographic
Many coastal applications—such as monitoring for
measurements, as is also planned for ACE (NASA, 2007).
Harmful Algal Blooms (HABs), ecosystem-based fisheries
management, and research on benthic habitats including
B oth the NASA Ocean Biology and Biochemistry
coral reefs and coastal wetlands—require greater spatial
(OBB) program and the National Research Council’s (NRC)
resolution and additional spectral bands than are currently
decadal survey plans call for a mix of ocean color satellite
available from most satellites to resolve the complex optical
mission types that would help ocean scientists answer the
signals that coastal waters produce. These measurements
high-level science questions they now face.
historically have been made from airborne sensors, usu-
ally flown by airplanes over a particular region. Airborne
hyperspectral observations are well suited for routine stud-
Global Hyperspectral Imaging Radiometer
ies of localized areas (e.g., coral reefs, seagrass beds) and
Answering the first two priority science questions above
for episodic events (e.g., HABs, oil spills) that require high
will require the development of advanced global remote
spatial or spectral resolution, or on-demand repeat times.
sensing capabilities. The planned NASA missions PACE/
The technology is well proven for mapping shallow-water
ACE will provide some of these new capabilities, including:
bathymetry and bottom type (e.g., Mobley et al., 2005;
Dekker et al., in press), mapping and monitoring coral reefs
• Ultraviolet (UV) bands to improve the separation
(Hochberg and Atkinson, 2003; Lesser and Mobley, 2007),
of chlorophyll and color dissolved organic matter (CDOM)
and detection of oil spills (Lennon et al., 2006). For example,
absorption and thus significantly improved accuracy of both
the Airborne Visible and InfraRed Imaging Spectrometer1
products. This capability is especially important because of
(AVIRIS), developed by the Jet Propulsion Laboratory (JPL),
projected changes in the ocean due to rising temperatures
made many flights over the Deepwater Horizon BP oil spill
and ocean acidification.
site.2 The hyperspectral information enabled researchers to
• Short wave infrared (SWIR) bands (1,200-1,700 nm)
map out the oil spill location and thickness. In addition, JPL
demonstrated by Moderate Resolution Imaging Spectroradi-
is supporting the construction of a portable hyperspectral
ometer (MODIS), which in that case led to improved atmo-
imager (i.e., the Portable Remote Imaging SpectroMeter
spheric correction over turbid coastal waters, in comparison
[PRISM]3).
to what was achieved with Sea-viewing Wide Field-of-view
Although the capability has been built and demon-
Sensor (SeaWiFS).
strated, past applications of this hyperspectral technology
• Additional bands in the UV that would help correct
have been limited to short surveys yielding single snapshots
for absorbing aerosols, a major source of uncertainty for
of a given coastal region. Routine and sustained surveys
the present generation of ocean color sensors particularly
of the U.S. coastal waters are not undertaken because it is
in coastal waters, and a specific UV band at 317.5 nm that
difficult to find the necessary funding to routinely fly these
would provide simultaneous ozone corrections.
airborne systems. Other countries, Australia and the People’s
• Improved atmospheric correction by determining
Republic of China in particular, have invested heavily in air-
aerosol altitude and type using a profiling LIDAR, advanced
borne hyperspectral imaging systems and routinely employ
polarimeter, or both as envisioned for ACE.
them in studies of their coastal and inland waters. The
United States also would benefit greatly from dedicated and
With these capabilities, it will be possible to separate
adequate support for airborne hyperspectral imaging systems
phytoplankton functional groups such as carbon exporters
that could be used for routine observations of coastal waters
(diatoms), nitrogen fixers (Trichodesmium sp.), calcium
or to respond to episodic events as needed.
carbonate producers (coccolithophores), and the microbial
High spatial resolution, hyperspectral measurements
loop organisms (Prochlorococcus sp.). It also will be pos-
also can be made from satellite missions and were rec-
sible to enable derivation and optimization of fluorescence
ommended as part of the Decadal Survey (NRC, 2007).
retrievals, which are particularly beneficial in quantifying
Airborne missions that gather such measurements provide
phytoplankton chlorophyll biomass during phytoplankton
them on an intermittent basis. Satellite hyperspectral remote
blooms and in coastal waters.
sensing would make these observations routine and allow
sustained application of the data for HAB detection, oil
Conclusion: Advanced ocean color remote sensing capa-
spill monitoring, shallow benthic habitat characterization,
bilities are central to answering questions related to chang-
and other research and research management applications.
ing conditions in the marine ecosystem and biogeochemical
cycles due to climate change.
1 See http://aviris.jpl.nasa.gov/.
2 See http://www.jpl.nasa.gov/news/news.cfm?release=2010-184; ac -
cessed February 8, 2011.
3 See http://airbornescience.jpl.nasa.gov/prism/.
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60 SUSTAINED OCEAN COLOR RESEARCH AND OPERATIONS
Conclusion: Almost all coastal research and operational
Satellite hyperspectral remote sensing mission was
applications require ocean color remote sensing capabili-
piloted with the Hyperion EO-1 mission.4 The EO-1 satel-
ties that are not routinely available. To sustain and advance
lite was launched in fall 2000 to demonstrate the technol-
these coastal applications, a high spectral and high spatial
ogy for the Landsat Data Continuity Mission. Because of
resolution sensor is required.
the satellite’s success, the research community successfully
advocated to continue the image acquisition from EO-1.
Data from the hyperspectral satellite SCanning Imaging
Geostationary Radiometers and Geostationary
Absorption spectroMeter for Atmospheric CartograpHY
Hyperspectral Imaging Radiometers (Type 4 sensors)
(SCIAMACHY), a European sensor designed to measure
various trace gases, aerosols and clouds, also are used for All current sensors except for the South Korean sensor
deriving ocean color measurements and have been applied Geostationary Ocean Color Imager (GOCI) are in polar orbit
to distinguish phytoplankton groups (Bracher et al., 2009). (see Chapter 4). South Korea launched the first geostation-
In addition, the Hyperspectral Imager for the Coastal ary ocean color sensor in June 2010 (Table 5.1). Although
Ocean (HICO;5 Lewis et al., 2009; Davis et al., 2010) was the limited geographic scope of this satellite makes it less
developed by the Office of Naval Research and installed relevant to the U.S. research and operational community,
on the International Space Station in late 2009. Because of access to these data would be valuable for developing future
mission constraints of the International Space Station, HICO geostationary missions in the United States. Initial Korean
currently collects only one image per orbit of selected targets, plans called for open data access in 2011.
but with good results. Although unable to provide global or Although the current systems in polar orbit can provide
highly accurate data, HICO is well suited for certain appli- global data coverage once every day or two, they offer only
cations that require high spatial or spectral data in coastal coarse spatial resolution. The resulting lack of data with high
waters during a limited period. HICO collects hyperspectral spatial and temporal sampling frequency was recognized
imagery (380-1,000 nm by 5.7 nm bandwidth) at ~100 m many years ago. Although near-daily data may be adequate
spatial resolution. Its primary applications are retrieval of for climate data records from the open ocean (assuming
coastal optical properties, bathymetry, bottom classification, data comparability from different sensing systems), daily
and water inherent optical properties (IOP), along with ter- acquisition is inadequate for critical coastal operational
rain and vegetation maps. Nevertheless, data availability to and research applications. Coastal waters and shorelines
the community is minimal. exhibit significant diurnal variability. A single geostation-
Plans also are under way for a global hyperspectral ary earth orbit (GEO) instrument could provide near-hourly
mission, the HyspIRI,6 as outlined by the Decadal Survey data updates for the continental U.S. coasts, as required to
(NRC, 2007). HyspIRI is a Tier 2 mission in the Decadal properly characterize important changes in coastal marine
Survey, which NASA plans to launch after 2020 (NASA, environments. For example, water clarity, tidal variability
2010). The goal of the HyspIRI mission, which is currently of shoreline and estuaries, effluent discharge, diffusion and
in the study stage, is to detect ecosystem changes due to absorption, and other parameters must be tracked frequently
climate change and human impacts on land and in the ocean. (IOCCG, 2008). Because many space agencies are interested
HyspIRI will make hyperspectral observations of radiance in and have plans for geostationary ocean color satellites,
from 380 to 2,500 nm at 10-nm resolution with a 60-m pixel a new International Ocean Colour Coordinating Group
at nadir. It will also be configured with a multispectral ther- (IOCCG) working group was formed to address require-
mal IR imager. The temporal revisit times are ~3 weeks for ments, advocate for coordination, and foster collaboration.
the visible/SWIR instrument and a one-week revisit for the Two U.S. options exist for increasing the supply of
thermal IR sensor. Besides looking at ecosystem changes, ocean color data from sensors in geostationary orbit. First,
HyspIRI will be able to map surface rock, soil, and snow a geostationary ocean color sensor hosted on a commercial
composition. Because it samples a fixed location in the satellite could be a cost-effective choice to obtain coastal
global ocean only once every three weeks, HyspIRI’s ability high-resolution or hyperspectral ocean color radiance (for
to measure change in fast-moving planktonic communities details see Appendix D). A second option is the GEOCAPE
is limited and not as useful for characterizing pelagic ocean mission. The Earth Science Decadal Survey (NRC, 2007)
conditions. The high spatial and spectral features of the r ecommended GEOCAPE as a Tier 2 mission, which
sensor will be used to assess coastal habitats on global and NASA plans to launch after 2020 (NASA, 2010). This mis-
seasonal scales, particularly benthic features such as corals, sion would focus on retrievals of tropospheric trace gases
seagrasses, and kelp. and aerosols and coastal ocean color from a geostationary
spacecraft. Although an ocean color GEOCAPE would
be optimized for coastal observation, its orbit also allows
for observations of offshore waters. This capability could
4 See http://eo1.gsfc.nasa.gov/. support research cruises within the covered area. Because
5 See http://hico.coas.oregonstate.edu; accessed May19, 2011.
GEOCAPE would be able to dwell over any area, it could
6 See http://hyspiri.jpl.nasa.gov.
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61
ADVANCING GLOBAL OCEAN COLOR REMOTE SENSING INTO THE FUTURE
TABLE 5.1 Current and Planned Type 4 Sensors (geostationary)
Spectral Coverage
Sensor/Satellite Agency Launch Date Swath Resolution Bands (nm)
GOCI/COMS KARI/KORDI 2010 2,500 500 8 400-865
(S. Korea)
GOCI-II/KMGS-B KARI/KORDI 2018 1,200 × 1,500 TBD 250/1,000 13 412-1,240 TBD
(S. Korea)
GEOCAPE NASA (USA) After 2020 300 m Hyperspectral at 10
nm
be used to cross-calibrate radiances measured by different information on vertical aerosol structure at a resolution
ocean color satellites in polar orbit. well beyond what’s required for ocean applications (<0.5
NASA has initiated plans and science and engineering km). LIDAR aerosol profiling measurements, simultane-
studies to equip GEOCAPE with the high spatial and tempo- ous with passive radiometric data, will enable unsurpassed
ral resolution required for coastal research.7 The capabilities atmospheric corrections that will result in vastly improved
of the geostationary ocean color sensor include: multiple ocean geophysical parameters. This capability is currently
sampling per day of continental U.S. coastal waters and available from CALIPSO (Cloud-Aerosol LIDAR and Infra-
Great Lakes, 300- to 375-m spatial resolution and hyperspec- red Pathfinder Satellite Observation) and is planned for the
tral resolution (with capability of binning spectral bands), ACE mission.
broad spectral coverage including UV-visible spectrum In addition to aerosol assessments, LIDAR remote
(VIS), near-infrared (NIR), and SWIR bands, high signal- sensing can measure the ocean’s light-scattering proper-
to-noise ratio (SNR) and dynamic range, cloud avoidance, ties independent of passive radiometer observations. Mea-
minimal polarization sensitivity (<0.2 percent), minimal sures of LIDAR light scattering are related to particulate
stray light, narrow field-of-view (FOV) optics, low scatter concentrations in the mixed layer (e.g., Churnside et al.,
gratings (<0.1 percent), no image striping or latency, and the 1998). Airborne LIDAR have been used for some time to
capability of performing solar and lunar on-orbit calibration.8 demonstrate the ability to make profiles of light scattering
at 532 nm and 355 nm into the water column (Wright et al.,
Conclusion: The availability of a geostationary satellite 2001). Most recently, this technique has also been applied to
would give federal agencies concerned with the degrada- LIDAR measurements from space with data from CALIPSO
tion of coastal habitats the necessary capabilities to monitor (Hu, 2009). Radiative transfer modeling and observational
the near-shore environment. data indicate that with an 100-m eye-safe Nd:Yg laser at an
altitude of 600 km, sufficient subsurface scattering values
can be retrieved to >15 m in clear ocean waters and to 5 m
Active Remote Sensing—LIDAR—to Measure the
in turbid coastal waters. To cover this full range of optical
Ocean’s Scattering Properties and Phytoplankton
conditions, space-based measurements will require 1 to 2-m
Variable Fluorescence
vertical resolution and a LIDAR angle of incidence of 15
Vertical changes in light-scattering properties measured degrees relative to nadir (to avoid detector saturation at the
through the atmosphere and into the ocean from a space- surface). However, LIDAR will not provide global coverage
based LIDAR9 can provide important new information for and thus will benefit from simultaneous passive remote sens-
solving major ocean carbon and biogeochemistry science ing to obtain the global coverage.
questions. Future missions that use measurements of water- LIDAR also could enable the measurement of the
leaving radiances to retrieve geophysical parameters related photosynthetic rate and the physiological state of phyto-
to ocean elemental cycles depend on accurate atmospheric plankton. LIDAR-based fluorescence has advantages over
corrections. This requires a strict accounting for the contribu- passive, solar-stimulated fluorescence (such as implemented
tion of absorbing aerosols to top of the atmosphere (TOA) on MODIS and described previously). This is because the
radiances, including information on their vertical distribu- laser source provides a consistent input of radiance and
tions and total optical thickness. LIDAR measurements, the changes can be measured over very short time peri-
both ground-based (e.g., Micropulse) and space-based (e.g., ods, enabling the determination of variable fluorescence.
Geoscience Laser Altimeter System [GLAS]), can provide Changes in variable fluorescence appear to behave in a
consistent manner under a variety of environmental condi-
tions, although a few stresses create unique behaviors. One
7 See http://geo-cape.larc.nasa.gov/.
of these conditions is iron-limited growth in the presence
8 See http://oceancolor.gsfc.nasa.gov/DOCS/.
of high macronutrient concentrations. However, techniques
9 LIDAR refers to a technology that measures the property of a target by
illuminating it with light and detecting the reflected light.
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62 SUSTAINED OCEAN COLOR RESEARCH AND OPERATIONS
have been developed to distinguish these iron-limited regions model. These spectrum matching approaches use both the
from iron-replete areas (e.g., Behrenfeld and Kolber, 1999; radiance magnitude and shape to determine the environ-
Behrenfeld et al., 2009). Therefore, remote sensing assess- mental conditions that generate the best-fit spectrum, i.e., to
ments of the variable fluorescence can provide a means for determine quantities such as bottom depth and type, or water
globally defining HNLC conditions, monitoring temporal absorption and backscatter coefficients. Spectrum-matching
shifts in physiological province boundaries, and establishing makes full use of the available spectral information at all
functional links between new iron inputs (e.g., dust deposi- wavelengths and has proved successful in the inversion
tion events) and ecosystem responses. of airborne hyperspectral imagery (Mobley et al., 2005;
Phytoplankton fluorescence kinetics has been measured Lesser and Mobley, 2007). These algorithms warrant further
in the field for more than 20 years and, through NASA investigation by the broad ocean color community. Indeed,
support, has been successfully measured from aircraft it is possible that spectrum matching to the TOA radiances
(Chekalyuk et al., 2000). The “pump and probe” technique could be used to effect a simultaneous atmospheric correc-
employed for these airborne tests will need to be modified for tion and bio-optical inversion, but this has been only briefly
space-based applications to reduce LIDAR energy demands investigated for multispectral systems (Chomko and Gordon,
and to meet eye safety requirements. Technological solutions 2001; Chomko et al., 2003; Stamnes, 2003). Furthermore,
for these issues are under development. the potential for climate change and the complexity of the
Globally defining and monitoring physiological prov- processes regulating the color of the ocean together raise
inces through satellite variable fluorescence measurements questions about the suitability of empirical approaches in
will require aggregation of multiple LIDAR returns to future oceans. Clearly, empirical band ratio algorithms are
improve signal to noise ratios. Measurements are needed at locked into the era during which these datasets are collected
midnight and at dawn to determine maximal variable fluores- (Dierssen, 2010). Better assessment of ocean color in the
cence and the relative nocturnal percentage decrease in vari- future may come from creating advanced ocean color algo-
able fluorescence (both critical diagnostics). This approach rithms that assess independently the different dissolved and
would require two satellites and would also provide informa- suspended materials that absorb and scatter light in the sea.
tion on the degree of midday light inhibition of photosyn- Similarly, improved atmospheric correction procedures
thetic electron transport. The excitation laser wavelength may be required due to global change. Present atmospheric
must penetrate a wide range of ocean waters (e.g., 532 nm correction approaches assume fixed relationships between
from a Nd:Yg laser) and be effectively absorbed by chloro- near-infrared and visible aerosol optical properties. Changes
phyll. Simultaneous Raman measurements at 651 nm are also in the chemistry and light absorption characteristics of
required for baseline calibration. Additional capabilities for aerosols that are expected under future climate conditions
detecting fluorescence at high spectral resolution (1-2 nm) would violate the assumption of constancy in aerosol optical
would expand the utility of the LIDAR measurements by properties. Present plans for the ACE ocean ecology spec-
allowing detection of specific phytoplankton groups through trometer (OES) include high-quality satellite observations
taxon-specific fluorescence features. in the ultraviolet spectral region (as short as 345 nm). These
planned observations will enable scientists to implement
flexible atmospheric correction models that allow aerosol
Improving Atmospheric Corrections, Ocean Color
optical properties to vary, as would be anticipated in future
Algorithms, and Products
climates.
The availability of new satellites and additional spec-
tral bands will require improvements in algorithms and
Validation
atmospheric corrections. In addition, the creation of a more
comprehensive field dataset and the use of standardized Even a limited number of comprehensive datasets for
sampling protocols would significantly increase the quality selected water and atmospheric conditions would greatly
of data products. advance ocean color remote sensing and environmental
optics in general. A comprehensive dataset would have all
the information needed to do a “round trip” radiative trans-
Atmospheric Corrections and Algorithm Development
fer (RT) calculation to propagate sunlight from the TOA,
Advances in bio-optical algorithms and atmospheric through the atmosphere to the sea surface, through the sea
corrections are required to make full use of hyperspectral surface into the water, from the water back to the atmosphere,
data now becoming available from aircraft sensors. As with and finally through the atmosphere to the sensor (additional
atmospheric correction, other types of bio-optical inverse details about this round-trip radiative transfer calculation are
models have been developed by the hyperspectral airborne in Appendix C). This RT process is the physical basis for all
imaging community. A broad class of such algorithms uses ocean color remote sensing and must be fully understood
spectrum matching of the atmospherically corrected Lw either when evaluating the performance of any particular sensor
to a pre-computed database of spectra or to a semi-analytic
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63
ADVANCING GLOBAL OCEAN COLOR REMOTE SENSING INTO THE FUTURE
and the products it generates. To date, no entity has collected Atmospheric measurements:
a truly comprehensive dataset that satisfies these RT needs.
Comprehensive oceanic and atmospheric datasets are • Sea level pressure, temperature, humidity, and wind
needed for: speed
• Cloud condition and sea state
• development and validation of remote sensing inverse • Sun photometer measurements
models and algorithms (i.e., TOA ocean color radiances → • Direct and diffuse spectral irradiance incident onto
atmospheric correction algorithm → water-leaving radi- the sea surface
ance or remote sensing reflectance → bio-optical inversion • Above-surface upwelling spectral radiance in the
algorithm → environmental products); direction needed to determine the water-leaving radiance
• identification of weaknesses in existing algorithms
and guidance for the development of improvements; and Oceanic measurements:
• validation of coupled oceanic and atmospheric RT
forward models, which underlie the development of both • Spectral absorption, beam attenuation, and backscat-
sensors and algorithms, and of inverse models, which are the ter coefficients
foundation of all remote sensing. • Measurements of CDOM and CDOM spectral and
fluorescence characteristics
• Concentrations of dissolved organic carbon (DOC),
Field Data Standards and Standardized Sampling
POC, and particulate inorganic carbon (PIC)
Protocols
• Phytoplankton carbon biomass and pigment
The measurements from MOBY, the current U.S. vicari- concentrations
ous calibration site off Lanai (Hawaiian Islands), meet strict • Net primary production, net community production,
National Institute of Standards and Technology (NIST) stan- and carbon export rates
dards. However, users of field instruments that generate data • Phytoplankton fluorescence and fluorescence quan-
for bio-optical algorithm development or validation do not tum yields and taxonomic groups
always meet recommended protocols or use defined calibra- • Particle size distribution
tion standards. Future field observations need standardized, • Downwelling (and preferably also upwelling) spec-
well-calibrated measurements that adhere to protocols to tral plane irradiance
help ensure quantitative comparison of observations.10 For • Upwelling spectral radiance
example, the chlorophyll concentration has long been the • Bottom depth and spectral reflectance in optically
principal data product derived from satellite ocean color of shallow waters
interest to oceanographers. There are several different tech-
niques for measuring chlorophyll but no accepted national
Extending Satellite Ocean Color Products to the
or international standard protocol. To fill this need, NASA
Vertical Dimension
hosted a series of round-robin comparisons to evaluate dif-
ferent methods and to promote guidelines and procedures Ocean color remote sensing provides information only
for measuring chlorophyll.11 Despite this effort, few research about the surface of the ocean, at spatial scales ranging from
labs to date adhere to these standard procedures developed kilometers to global. The vertical dimension is only partially
for chlorophyll. In addition, sky radiance measurements are explored, from the surface to about 15-20 m in the clearest
necessary to characterize, for example, aerosol properties. waters, and from the surface to only a few tens of centimeters
Similar issues exist for the next-generation products, such as in turbid waters (i.e., the “penetration depth” from which
CDOM, particulate organic carbon (POC), particle size dis- originate 90 percent of the photons exiting the water).
tribution, primary productivity, net community production, However, phytoplankton grow throughout the lit upper
carbon export flux, etc. Future satellite ocean color missions layer of the ocean to depths of 100 m or more. Therefore,
need to take on the creation and community-wide adaptation ocean color sensors miss much of the information of interest;
of field measurement standards and field sampling protocols this is particularly true for the Navy, which is interested in
for future satellite ocean color data products. optical properties that extend from the surface to the bottom
The minimum set of measurements that would need to of the ocean.
be made, and for which standards and protocols need to be Determining the total amount of biomass or primary
developed and followed (when appropriate), can be sum- productivity in the ocean currently requires assumptions
marized as follows: about how phytoplankton cells are distributed with depth:
either homogeneously when the upper ocean is well mixed
or with a vertical structure. This vertical structure results
10 See http://www.ioccg.org/reports/simbios/simbios.html. from intermingled physical and biological effects and often
11 See http://oceancolor.gsfc.nasa.gov/DOCS/SH2_TM2005_212785.
exhibits a deep maximum whose depth precisely depends
pdf.
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64 SUSTAINED OCEAN COLOR RESEARCH AND OPERATIONS
SUSTAINING OCEAN COLOR REMOTE SENSING
on the balance between physical and biological forcings.
OVER THE LONG TERM
The vertical structure is presently reconstructed using sta -
tistical relationships between the satellite-derived values
Long-Term Mission and Budget Planning
and the vertical profile established from in situ information
(e.g., Morel and Berthon, 1989; Uitz et al., 2006) or using
Long-term planning is necessary to provide continuity
the concept of biogeographical provinces to which a given
between satellite missions and to ensure sensor overlap. In
shape is assigned (Longhurst, 1998). These techniques use
general, it takes six to eight years to move an ocean color
a small number of measured vertical profiles. Consequently,
mission from conception to launch. This time frame can be
they perform poorly when applied to satellite pixels that
much longer in a shrinking budget environment or when
include by, definition, all possible cloud-free areas in the
other problems arise. For example, the SeaWiFS concept
ocean.
was developed in 1986, but launch did not occur until 1997.
New autonomous-profiling floats and gliders equipped
Furthermore, mission and budget plans need to include
w ith optical instrumentation are now available, which
provisions for all mission requirements throughout the mis-
provide vertical profiles of quantities such as chlorophyll
sion’s life span and beyond. SeaWiFS was successful in part
fluorescence or the particulate backscattering coefficient
because mission planning and budget, through support from
(Boss et al., 2008; Boss and Behrenfeld, 2010). In the case
the EOS/MODIS program, included provisions not only for
of gliders, radiance and irradiance sensors are now routinely
the sensor and satellite, but also for many of the essential ele-
integrated for subsurface profiles (Schofield et al., 2007). A
ments such as vicarious calibration, stability monitoring, col-
large deployment of these floats could enhance the satellite
lection of in situ validation data, and a mission team with the
data record by providing the missing vertical dimension.
tools to handle data processing and reprocessing. In addition,
Such arrays were initially designed and deployed for physical
SeaWiFS experienced a long launch delay, which provided
oceanography (the “Argo” array, e.g., Roemmich and Owens,
sufficient time to make sure the necessary infrastructure
2000). These floats sample the water column between the
was in place for the calibration and validation effort. Less
surface and about 2,000 m, covering horizontal scales from
than a year from the launch date, it remains unclear who
~1 m to ~1,000 km and temporal scales from one day to
will fund and conduct the vicarious calibration for VIIRS
several years. Interestingly, the intersection between the
on NPP and who will be processing and reprocessing the
spatio-temporal domains covered by both remote sensing
data. In addition, planning for in situ data collection has
and profiling floats encompasses the mesoscale oceanic pro-
begun only recently. These missing elements of the VIIRS/
cesses as well as the seasonal cycle of mixed layer dynamics
NPP mission contribute significantly to the uncertainty about
and its impact on biomass cycles. These phenomena are
the data quality of its ocean color radiance and ocean color
fundamental to understanding the impact of physical forcing
products, and if unresolved, might jeopardize the success of
on ocean biology and biogeochemical cycles.
the mission.
Such Bio-Argo floats would be an ideal addition to an
integrated observing system that includes ocean color satel-
Conclusion: A satellite mission that does not include plan -
lites, optically equipped gliders, and ship-board studies.
ning and budgeting for all essential elements of a mission
These floats would make vertical data available indepen-
(e.g., vicarious calibration, stability monitoring, in situ
dent of cloud coverage and with good temporal resolution
data collection and archiving, algorithm development, data
(Claustre et al., 2010). The optical Argo floats could be used
processing and reprocessing; see Chapter 3 for additional
to refine the satellite algorithms, improve global primary
details), jeopardizes the success of the mission for many
production estimates, estimate particulate organic carbon
uses, especially for climate assessments.
in the water, and even estimate the total sinking carbon flux
(Bishop and Wood, 2009).
Recommendation: To ensure success, a mission should
include long-term planning and budgeting for all require-
Recommendation: An array of “bio-geochemical floats”
ments of the mission.
should be implemented and progressively expanded.
Long-Term Planning for Data Stewardship
International collaboration is ongoing in order to build
from the experience of the Argo network (e.g., Johnson et
As discussed in previous chapters, producing high-
al., 2009). The IOCCG has also set up a working group on
quality ocean color data is complex and requires a concerted
this topic and will issue a report in 2011.12
effort. As information becomes available about the sensor’s
behavior, the continuous vicarious calibration effort and data
reprocessing at regular intervals are vital to generate high-
quality products. Therefore, plans for product development
and data access and archiving need to be in place well in
12 See http://www.ioccg.org/groups/argo.html.
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ADVANCING GLOBAL OCEAN COLOR REMOTE SENSING INTO THE FUTURE
0 data and metadata is required to allow subsequent
advance of the sensor launch. Plans also need to specify how
reprocessing and merging of individual mission data into
efforts carry over from one mission to the next to preserve
sustained climate data records.
data continuity.
Currently, NASA’s Ocean Color Biology Processing
Group (OBPG) at Goddard Space Flight Center (GSFC) is Both NASA and NOAA support ocean color applica-
internationally recognized as a leader in producing well-cali- tions, with NASA focused primarily on research and devel-
brated, high-quality ocean color data products from multiple opment and NOAA focused on operational uses. Because
satellite sensors. For example, processing and reprocessing both agencies have a strong interest in climate and climate
from Level 0 to Level 2 imagery require the most skill and impacts, they share a common interest in climate data records
resources, including access to pre- and post-launch calibra- (CDRs).
tion data, models, ancillary data and significant computa- As previously discussed, NOAA currently lacks the
tional resources for production, archiving, and distribution. demonstrated capacity to readily produce high-quality ocean
In effect, these production steps determine the quality of color products. Moreover, the committee anticipates major
the final data products. Access to all raw, processed, and challenges to generating high-quality products from the
metadata are critical if long-term time-series of ocean color VIIRS/NPP data. However, a recent NOAA report (NOAA,
products are to be constructed across different mission data- 2010) makes a recommendation to build the in-house capac-
sets (à la Antoine et al., 2005). ity for end-to-end data processing/reprocessing. If NOAA
The Ocean Color Biology Processing Group at NASA builds its own data processing/reprocessing group, two
GSFC currently provides this service for CZCS, SeaWiFS, independent federal groups will be developing ocean color
and MODIS data. As new algorithms are developed, the products. Having two groups independently process ocean
OBPG has repeatedly reprocessed all ocean color data from color data would provide the benefit of products that could
SeaWiFS and MODIS to ensure a continuous, intercalibrated be tailored to the respective user-group. However, it results
dataset of climate-quality data. To be able to routinely in some redundancy and potential questions about merg-
reprocess the data, the raw data, radiance at the TOA, and ing datasets for building long-term climate records. Given
water-leaving radiance needs to be archived and available for NASA’s experience with end-to-end data processing, NOAA
the long term. In particular, the most recent version of the can draw on that agency’s expertise to build its own capacity.
water-leaving radiance needs to be readily available to ensure
Conclusion: NOAA would greatly benefit from initiating
users can generate their own derivative products.
and pursuing discussions with NASA for an ocean color
T he OBPG currently provides broad access to
mitigation partnership that would build on lessons learned
ocean color data by creating and deploying SeaWiFS Data
from SeaWiFS and MODIS, in particular.
Analysis System (SEADAS), an image-processing software
that can be installed on many different computer platforms.
The OBPG has developed the necessary modules to make A near-term option for the partnership could be a real
data easily accessible and has built the necessary structure or virtual “center” involving NOAA and NASA personnel,
to archive the data, including the radiance at TOA and the with contributions from the academic research community.
water-leaving radiance. NOAA is currently building capacity An important step in any research-to-operations transition is
but does not have the know-how to provide these compre- for researchers to work directly with the people developing
hensive services. Although NOAA’s National Climate Data operational capabilities. Thus, such a virtual center’s activi-
Center (NCDC) plans to archive a climate-level13 radiance ties could include: research and development related to ocean
data record, it is unclear how accessible the data will be. color products that serve research and operational users; and
Easy access will be an important factor in contributing to processing/reprocessing of data from U.S. and foreign ocean
the successful application of the ocean color data. color missions to ensure a sustained time-series of calibrated
imagery to identify long-term trends and calibration and
Conclusion: Because of the potential need to reprocess the validation activities. These involve for example, a NOAA-
raw data years after collection, the committee concludes operated MOBY-like site, among other activities.
that the water-leaving radiance and the radiance at the
TOA need to be archived together with the metadata for the Recommendation: To move toward a partnership, NASA
long term. In addition, the most recent version of the water- and NOAA should form a working group14 to determine
leaving radiance needs to be readily accessible to all users. the most effective way to satisfy each agency’s need for
ocean color products from VIIRS and to consider how to
Conclusion: A permanent archive for repackaged Level produce, archive, and distribute products of shared interest,
13 Climate-level means repackaged data so they look like a MODIS 14 The committee was informed in March 2011 that NOAA and NASA
granule and metadata repackaged accordingly to ease the reprocessing of have formed a new ocean color working group with a composition and
the Level 0 data. charge that encompasses many of the recommendations listed above.
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66 SUSTAINED OCEAN COLOR RESEARCH AND OPERATIONS
such as CDRs, that are based on data from all U.S. ocean cessing, reprocessing, calibration, validation, model imple-
color missions. This group should be composed of agency mentation, and distribution for satellite ocean color data.
representatives and also include outside experts from the Ideally, such a group will be flexible and able to respond
ocean color research and applications community. to and resolve a wide range of issues; the OBPG at GSFC
responsible for SeaWiFS and MODIS ocean color data
products provides a good model. The team has all required
This working group could be the focal point for U.S.
scientific, engineering, and technical skills to interact, for
contributions to the Ocean Colour Radiometry Virtual Con-
example, with competitively selected NASA science teams
stellation (OCR-VC), for articulating U.S. needs for specific
for individual missions.
data from international missions, and for helping negotiate
The committee judges it to be most efficient to establish
how those needs would be met. As is currently done by the
an interagency team to be involved with all ocean color mis-
Ocean Color Group at GSFC, the new working group would
sions over the long term and to interact with competitively
be the ideal mechanism to routinely interact with ocean
selected science teams for individual missions. This would
color experts in the national and international academic
minimize the loss of institutional memory.
community. Subcommittees of existing federal advisory
committees—the Earth Science Subcommittee of the NASA
Conclusion: Long-term planning is needed that focuses
Advisory Committee and NOAA’s Scientific Advisory Board
on building a long-term data record, instead of focusing
(SAB)—could provide oversight. To the extent possible, the
on building individual satellite missions. A working group
working group could develop and maintain centralized teams
that is maintained across missions is the best choice to
with all necessary skills to evaluate product quality and to
coordinate this planning.
take appropriate measures to improve quality for the long
term. These teams would provide avenues for stakeholders
Specialized technical and scientific expertise in various
to engage and would enable the research community to con-
aspects of ocean color radiometry exists within the civil
tinuously demonstrate its need for, and ensure the existence
service at NASA, NOAA, NIST, Office of Naval Research
of, overlapping programs that can maintain the essential
(ONR), and the Naval Research Laboratory (NRL), and is
requirements (i.e., missions and accompanying infrastruc-
concentrated at NASA’s GSFC. This expertise includes sen-
ture) to generate multi-decadal climate-quality data records.
sor design and calibration, aerospace engineering, systems
To achieve a multi-decadal climate-quality data record will
e ngineering, hydrological optics, physics, atmospheric
necessitate a permanent planning function at the international
physics, biogeochemistry, etc. Maintaining strong technical
level (see discussion below).
expertise within the civil service allows the agencies to tackle
Recommendation: This working group should engage with technical questions quickly, to provide technical oversight
the scientific community, develop a unified and coordinated of major instrument contracts, and to support the vigorous
voice, provide long-term vision and oversight, and engage exchange of scientific ideas with the academic community
with the international community. and other agencies.
Recommendation: NASA and NOAA should ensure suffi-
Building and Maintaining the Ocean Color Workforce
cient levels of staffing in areas critical to the continuation
of ocean color research and climate data collection.
Developing and using high-quality ocean color
research products requires a highly specialized and trained
The committee also encourages NASA and NOAA to
workforce with a diverse set of technical skills. Maintaining
expand the use of academic researchers in Intergovernmental
the viability of the field requires experts who know how to
Personnel Act15 positions both in managerial and technical
design and build a sensor; test and calibrate it; design and
roles. This will expand the influx of ideas from academia
operate vicarious calibration sites; conduct validation and
into the federal agencies and will increase the number of
calibration efforts; process, reprocess, and archive ocean
academic researchers familiar with government procedures
color data; and make these products easily available to
and policies. Similarly, NASA and NOAA could enter into
users. In addition, data users need to be trained in satellite
agreements to facilitate temporary exchange of scientists and
oceanography.
engineers to encourage sharing of ideas and understanding of
each agency’s missions, strengths, and weaknesses.
Building and Maintaining the Expertise in Government
Agencies
As we learned from the SeaWiFS/MODIS experience, a
team with the right mix of skills and knowledge is essential
15 Through the IPA program, NASA or NOAA can temporarily bring
to advancing the quality of ocean color products. A group
individuals from academia and state and local governments to the agency
of experts needs to take responsibility for acquisition, pro- to provide scientific, administrative, and managerial expertise.
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ADVANCING GLOBAL OCEAN COLOR REMOTE SENSING INTO THE FUTURE
Building and Maintaining the Expertise in Academia other courses. While the course at the University of Maine
focuses on hands-on training with a strong laboratory and
Experience from all NASA ocean satellite missions
field component, the IOCCG course would focus on current
demonstrates the importance of supporting a competitive
critical issues and emerging topics of optical oceanography
research program associated with each mission. Researchers
and ocean color remote sensing research.
help improve data products, advance ocean color applica-
The large number of applications for ocean color prod-
tions, and train the new workforce.
ucts demonstrates the demand for these intensive summer
Scientists have contributed to significant, and in some
courses. The limitation in both cases is funding to cover
cases, immediate improvements to data products by con-
faculty salaries, travel, laboratory and field costs, and student
ducting research on topics such as in-water and atmospheric
per diem expenses. The committee considers such costs to
algorithms, sensor performance, and regional validation
be small compared to the benefits of maintaining a highly
of in-water and atmospheric correction algorithms. This
trained and skilled workforce.
research can provide critical feedback to the mission if there
is clear communication with the project team, via open meet-
Collaborating and Coordinating Internationally to
ings and workshops where results are discussed and their
Sustain Ocean Color Observations
meaning debated.
For example, application scientists were among the
Two international committees—the IOCCG and the
first to note that initial SeaWiFS processing had yielded
OCR-VC16 organized under the Committee on Earth Observ-
anomalous water-leaving radiance spectra with unusually
ing Satellites (CEOS)—support international cooperation
low radiance in the blue bands (in fact, negative radiances in
for ocean color research and operations. The IOCCG is a
many coastal waters). It required several years of interaction
committee of users and space agency representatives. Among
between applications scientists and the SeaWiFS project, and
the primary IOCCG products are monographs on a wide
several reprocessings, to fix the problem.
range of topics that provide essential consensus advice to
In addition, NASA, NSF, and NOAA have supported
those planning and operating satellite ocean color missions.
investigators who use ocean color imagery for basic research.
The OCR-VC is a consortium of representatives from agen-
The applications described in Chapter 2 lead to better under-
cies that operate satellite ocean color missions. It seeks to
standing of ocean processes and make important societal
coordinate activities related to post-launch calibration and
contributions.
validation, data merging, and sharing of essential pre-launch
Further, competitive research programs often result in
characterization and calibration information. OCR-VC also
new applications for or new approaches to using ocean color
promotes training programs and outreach.
data; these new applications add value to the mission. Lastly,
The activities of the IOCCG and OCR-VC are increas-
research projects naturally integrate graduate students into
ingly important to U.S. users of satellite ocean color products
the ocean color community, which is critical to maintain
because neither NASA nor NOAA will provide all required
a capable workforce in the private sector, at NASA and at
data products for at least a decade. For example, the United
NOAA, with continuity through missions.
States currently has no geostationary mission in orbit and
limited availability of high spatial resolution imagery (250-
Training and Recruitment Through Summer Courses to 300-m pixels). Second, non-U.S. missions have the poten-
tial to provide essential backup for global imagery in the
Many scientists in academia and government, and sev-
event of a failure during the launch or in the early stages of
eral federal agency program managers, are graduates of sum-
a U.S. mission. Finally, merging data from multiple sensors
mer courses such as those at the University of Maine or Cor-
significantly enhances global coverage. For these reasons, it
nell University. For example, the intensive summer course in
is essential that NASA and NOAA continue to support the
optical oceanography and remote sensing at the University
activities of the IOCCG and the OCR-VC.
of Maine was first taught in the mid-1980s by experts from
The production of a climate-quality long-term record
around the world. It is held every two or three years and has
of ocean color requires international collaboration. As dis-
achieved an international reputation as a career-molding
cussed above, establishing a climate-quality long-term data
course. Applications always far outnumber the 12 to 15
record exceeds the capacity and mandate of a single U.S.
seats available. The course has evolved with the science to
agency. In general, it is difficult to maintain such long-term
include lectures and extensive hands-on laboratory and field
commitments due to budget uncertainties. International
work, using many instruments of optical oceanography and
collaboration to establish a long-term record can be a good
vicarious calibration. NASA and other federal agencies have
hedge against the uncertain funding from any single space
provided substantial funding for the course.
agency or nation.
The IOCCG is currently organizing a recurring sum-
mer lecture series, “Frontiers in Ocean Optics and Ocean
Colour Science.” This class would build on and complement
16 See http://www.ioccg.org/ groups/OCR-VC.htm.
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68 SUSTAINED OCEAN COLOR RESEARCH AND OPERATIONS
Examples of successful international collaboration effort. Essential components would include revisiting cali-
already exist in several domains. The Centre National bration factors and how they change over time for multiple
d’Etudes Spatiales (CNES) and NASA have established a sensors; updating in situ databases for product validation;
fruitful partnership to prepare, implement, and exploit altim- evaluating quality of in situ data; generating match-up data-
eter missions (Jason series and Topex/Poseidon), leading to sets (satellite and in situ) to confirm accuracy; incorporating
long-term, global sea-level data records that demonstrate a VIIRS/NPP data into the time-series; and other activities.
gradual increase in sea level (IPCC, 2007). The Group for
Conclusion: The CCI initiative presents an opportunity for
High-Resolution Sea Surface Temperature (GHRSST) has
real progress toward establishing a seamless time-series
brought together many space agencies involved in measur-
for a climate-quality ocean color data record. Engaging
ing sea surface temperature from space in order to establish
experts at NASA and NOAA could significantly contribute
standards, perform comparisons of products and algorithms,
to the success of this initiative with mutual benefits for the
and produce global datasets by merging data from different
United States and the international community.
satellites.
These efforts involved not only space agencies but also
Conclusion: The IOCCG is the logical entity to lead
the science community, which has to be organized in order to
the planning and to build international support for the
have a strong and single voice. The ocean color community
establishment of a global climate-quality ocean color data
still lacks this mechanism, but the creation of the OCR-VC
record. NASA’s and NOAA’s support for and engagement
represents a step forward. The OCR-VC provides a frame-
with this group will be essential to the success of these
work for agencies to strengthen collaboration and leverage
efforts.
individual efforts. The IOCCG is considering options for
how to make such a virtual constellation a reality for the
ocean color community.
CONCLUSION
Another promising development is ESA’s Climate
Change Initiative (CCI) to produce Essential Climate Vari- The expanding user community and the diversity of
ables (ECV; CDRs in NOAA/NASA terminology). ESA ocean color applications that fuel research and benefit ocean
selected ocean color as one of the first 10 ECV projects that ecosystem health demonstrate the critical need to sustain and
began in summer 2010. The goals for the ocean color ECV advance ocean color observations from satellites well into
are: generate the most complete multi-sensor global satellite the future. As discussed in detail in Chapter 2, ocean color
data products for climate research and modeling that meet remote sensing is the only way to obtain a global view of the
Global Climate Observing System (GCOS) ocean color ocean biology. Ocean color data are essential to improving
ECV requirements; quantify pixel uncertainties for different the understanding of the climate system, including global
regions; and assess the applicability and impact of ocean color carbon fluxes. Ocean color satellite observations also are
ECV products on ecosystem and climate models. Another key used to assess the health of the marine ecosystem and its
goal is to form teams of observational scientists and climate ability to sustain important fisheries. Any interruption in
modelers to ensure that ECVs are correctly incorporated in the ocean color record would severely hamper the work of
climate models and models of climate impacts. climate scientists, fisheries and marine resource managers,
ESA recognizes the importance of international coop- and an expanding array of other users, from the military to
eration for this project and lists NASA, NOAA, JAXA, and oil spill responders.
the IOCCG as external partners. Further, a closer NASA/ Increasing the spatial or temporal resolution, especially
NOAA-led partnership with ESA would be a major contri- in coastal waters, would enable further advances in research
bution to the OCR-VC and could stimulate participation by and resource management. In particular, an ocean color
other agencies (e.g., JAXA, ISRO), potentially bringing other satellite in geostationary orbit would fill an important gap in
expertise and satellite datasets into the project. From users’ observational capability (Appendix D). High spectral imag-
perspective, this international partnership could go a long ing and a satellite in geostationary orbit would significantly
way toward providing high-quality ocean color data from improve the ability to monitor for example HABs and coral
many different missions and for many applications. reef health. Similarly, the addition of Bio-Argo floats would
Prototype products of the first 10 ECVs will be available turn the two-dimensional satellite ocean color imagery
in 2011-2012. Complete time-series (from multiple sensors) into dynamic three-dimensional depictions of the ocean
will be available beginning in mid-2013. The objective for biosphere. These and other enhancements described above
the ocean color time-series is to reduce bias among sensors would add tremendous value to oceanography, but they will
(MERIS, SeaWiFS, and MODIS) to less than 1 percent, an be difficult to balance with the requirements to simply main-
ambitious goal that will require reprocessing of all satellite tain the current capabilities, especially in the current budget
datasets. environment. Thus, it will require careful and strategic long-
A NASA/NOAA-led project, similar to NASA’s SIMBIOS term planning, in addition to international collaboration and
program, could help meet this goal and complement the ESA coordination, to meet these diverse needs.
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ADVANCING GLOBAL OCEAN COLOR REMOTE SENSING INTO THE FUTURE
Mission planning proved the concept (CZCS) and led to vision for the development of U.S. ocean color missions and
the successful demonstration that water-leaving radiance can the delivery of ocean color products to users. The long-term
be of such high accuracy that climate trends can be quantified vision also needs to ensure the next generation of satellite
(SeaWiFS and MODIS). However, building a climate-quality oceanographers is sufficiently trained in order to maintain the
time-series comes with stringent requirements—most nota- required expertise at every level, from sensor engineering to
bly the need for continuity and sensor inter-calibration. Now, data processing and application.
planning will need to extend beyond the next mission and In the long term, simply sustaining the current capabili-
establish a strategy to sustain the climate-quality data record. ties of ocean color remote sensing will fall short of support-
ing the array of ocean color applications described in Chapter
Conclusion: A data-oriented long-term planning approach 2. Many ocean color applications require a commitment to
will need to replace a mission-oriented approach for the advancing current capabilities. Foremost, these advances
global climate-quality ocean color record. need to include hyperspectral and active imaging capabilities
and a sensor in geostationary orbit for coastal applications.
To develop this climate-quality time-series and to Therefore, the committee recommends above that
advance ocean remote sensing, strategic long-term plan - NASA and NOAA form a working group to determine the
ning and budgeting is required for all aspects of follow-on most effective way to satisfy each agency’s need for ocean
missions, including how data are reprocessed, accessed, color products from VIIRS and future ocean color sensors.
and stored across the individual missions. In addition, the This working group could be the focal point for U.S. collabo-
institutional memory and workforce need to be maintained rations with the international community and for articulating
and transitioned across individual missions to ensure some U.S. needs for specific data from international missions, for
measure of consistency and to avoid inefficiencies. NOAA helping to negotiate how those needs will be met and for
and NASA will continue to have mutual interests in the ocean advocating for advanced capabilities to support future ocean
color climate data record as well as in advances in remote color applications.
sensing. Therefore, they would benefit from sharing in the Moreover, because the community will require distinct
development of these long-term plans. types of satellite sensors to meet all data product needs, no
Going forward, a national working group similar to single nation will be able to develop or even maintain capa-
the international IOCCG working group, with strong gov- bilities on its own. NASA and NOAA will need to continue
ernance, clear mandate, and financial resources, is needed to actively engage and contribute to the development of the
to guide the direction of ocean color remote sensing in the international OCR-VC. Ocean color remote sensing needs to
United States and to implement changes at the national level. be an internationally shared effort.
This committee also would provide oversight and long-term
