PNNL-13501 - Pacific Northwest National Laboratory

Study Control Number: PN99018/1346
Development of an Aquatic Bio-Optical Monitoring Buoy
Dana Woodruff, Paul Farley, Karen Steinmaus
Satellite algorithm development is needed in coastal and nearshore waters to take advantage of a new generation of higher
resolution, recently launched satellites. This project evaluated the use of a bio-optical monitoring buoy with a
complement of environmental and optical sensors to provide near real-time, remotely accessible data for algorithm
development and natural resource/damage assessment of coastal and inland waters.
Project Description
This project developed an approach to collect bio-optical
data in coastal nearshore, and inland waters using a near
real-time remotely accessible bio-optical monitoring buoy
designed to validate ocean color algorithms for satellites
collecting data in coastal environments. The recent
successful launch of the NASA Sea-Viewing Wide Fieldof-View
Sensor ocean color satellite and scheduled
launch of future ocean color sensors requires validation,
modification, and development of ocean color algorithms
for specific use in optically complex nearshore waters. In
situ calibration data has traditionally been collected from
shipboard platforms, requiring labor-intensive field
efforts. This project will provide a streamlined, flexible
approach to collect bio-optical data in geographic regions
(coastal, nearshore, or inland waters) that require further
algorithm development. A portable buoy with a unique
complement of environmental and optical sensors will
allow for a quick response monitoring capability for
natural resource and/or damage assessment in inland and
coastal waters.
Introduction
Global climate change issues have necessitated
multidisciplinary assessment approaches, including the
use of satellites to understand the role of oceanic
phytoplankton and primary production in global ocean
carbon cycling. Although coastal waters account for
approximately 10% of the surface area of the global
oceans, they contribute almost 40% of the total global
primary production. One of the differences between
coastal and oceanic primary production is thought to be
partly a consequence of human-induced activity and
associated impact to nearshore systems. To this end, the
role of satellite monitoring in coastal waters has become
increasingly important, including the ability to convert
satellite-acquired data into reliable estimates of
environmentally significant parameters.
The use of satellite ocean color imagery in biologically
productive coastal regions requires modification of
standard oceanic algorithms and development of new
algorithms for optical properties unique to coastal waters.
Nearshore waters contain higher concentrations and
greater varieties of optical constituents (chlorophyll,
suspended sediments, colored dissolved organic matter)
than oceanic waters. The first ocean color satellite, the
Coastal Zone Color Scanner was operational between
1976 and 1986 and provided extensive data on ocean
chlorophyll estimates; however, the algorithms and sensor
could not adequately address coastal waters due to a
limitation in gain and response of the sensor near land.
The second generation of ocean color satellites recently
became operational with the launch of the Sea-Viewing
Wide Field-of-View Sensor satellite which has improved
radiometric response and additional wavebands making it
more useful in coastal waters than Coastal Zone Color
Scanner was. NASA developed a well-calibrated and
validated suite of algorithms for chlorophyll estimation in
the open ocean. However, these algorithms are proving to
be inadequate for viewing coastal regions, which are
optically more complex. Rapid and accurate methods of
collecting in situ absorption (chlorophyll and DOM) and
backscattering (suspended particulates) data are needed to
develop these new algorithms and to define regional
algorithm boundaries for imagery application. Optical
and environmental data that can be collected from a
remote platform such as a buoy will reduce the cost
significantly and will provide temporal coverage that is
not available using traditional collection methods.
Results and Accomplishments
We evaluated the use of an aquatic bio-optical monitoring
surface buoy to collect ground-truth data for satellite
algorithm development in semiprotected coastal areas
(Figure 1 and the schematic in Figure 2). Incorporated
into the buoy platform were the following capabilities:
1) multipurpose combined satellite validation and
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