7.1 Introduction
Soon after the first satellite images of the Earth became available in the 1960s,
biological oceanographers started to wonder whether it was possible to measure the
ocean’s phytoplankton biomass from space. Yentsch (1965) first discussed the
distribution of chlorophyll and phaeophytin in the ocean and described how their
varying patterns might appear in satellite images. In 1967, the debut of the first
airborne spectroradiometer on the C-47 aircraft of the Woods Hole Oceanographic
Institute represented the birth of biological ocean remote sensing (Clarke et al.
1970). In the 1970s, several research institutions and research groups pioneered
instrument and radiative transfer theory development that provided the basis for a
proof-of-concept satellite mission. These included, for example, the Scripps
VisLab’s development of various spectroradiometers, the NOAA R/V Discoverer’s
optical survey of the Peru coastal upwelling, and theoretical work of Preisendorfer,
Morel, Gordon, Zaneveld, and their coworkers (e.g., Preisendorfer 1976; Morel and
Prieur 1977; Zaneveld 1982; Gordon and Morel 1983). After more than a decade of
effort, in 1978, the Coastal Zone Color Scanner (CZCS) was launched onboard the
Nimbus-7 satellite and, until 1986, provided unprecedented data to study the ocean’s
biology (Hovis et al. 1980). Initial results showed moderate success in estimating the
surface chlorophyll concentration (Gordon et al. 1980; Smith and Baker 1982), and
numerous studies of the ocean’s primary productivity, biogeochemistry, and
response to climate perturbations followed thereafter. These were summarized in a
special volume of the Journal of Geophysical Research (Mitchell 1994).
There was a 10 year gap between 1986 and 1996 before the next ocean color
sensor, the short-lived Ocean Color and Temperature Sensor (OCTS, Nov 1996–
June 1997), was carried aboard the Japanese Midori satellite. Soon thereafter, the
Sea-viewing Wide Field-of-view Sensor (SeaWiFS, August 1997–December
2010) was launched onboard the Orbview-2 satellite, ushering in the modern era of
continuous space-based ocean color observations (Hooker et al. 1992; McClain
2009). Since then, many follow-on ocean color sensors have been launched into
space by the U.S. NASA, the European Space Agency (ESA), and other international agencies. These include the Moderate Resolution Imaging Spectroradiometer (MODIS, 1999–present for Terra and 2002–present for Aqua, NASA), the
Medium Resolution Imaging Spectrometer (MERIS, 2002–2012, ESA), the Ocean
Color Monitor (OCM-1, 1999–present; OCM-2, 2009–present, India), and more
recently, the Geostationary Ocean Color Imager (GOCI, 2010–present, South
Korea) and the Visible Infrared Imager Radiometer Suite (VIIRS, 2011–present,
NASA and NOAA). For a reference, Table 7.1 lists the characteristics of several
ocean color sensors commonly used by the scientific community. After proper
calibration and validation, the frequent and synoptic observations of the global and
regional oceans from these large-swath satellite observations have been used in a
variety of research and applications well beyond the original scope of mapping
ocean chlorophyll. For example, ocean color observations have been used to study
the ocean’s biogeochemistry and primary production, to trace ocean circulation
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C. Hu and J. Campbell
Soon after the first satellite images of the Earth became available in the 1960s,
biological oceanographers started to wonder whether it was possible to measure the
ocean’s phytoplankton biomass from space. Yentsch (1965) first discussed the
distribution of chlorophyll and phaeophytin in the ocean and described how their
varying patterns might appear in satellite images. In 1967, the debut of the first
airborne spectroradiometer on the C-47 aircraft of the Woods Hole Oceanographic
Institute represented the birth of biological ocean remote sensing (Clarke et al.
1970). In the 1970s, several research institutions and research groups pioneered
instrument and radiative transfer theory development that provided the basis for a
proof-of-concept satellite mission. These included, for example, the Scripps
VisLab’s development of various spectroradiometers, the NOAA R/V Discoverer’s
optical survey of the Peru coastal upwelling, and theoretical work of Preisendorfer,
Morel, Gordon, Zaneveld, and their coworkers (e.g., Preisendorfer 1976; Morel and
Prieur 1977; Zaneveld 1982; Gordon and Morel 1983). After more than a decade of
effort, in 1978, the Coastal Zone Color Scanner (CZCS) was launched onboard the
Nimbus-7 satellite and, until 1986, provided unprecedented data to study the ocean’s
biology (Hovis et al. 1980). Initial results showed moderate success in estimating the
surface chlorophyll concentration (Gordon et al. 1980; Smith and Baker 1982), and
numerous studies of the ocean’s primary productivity, biogeochemistry, and
response to climate perturbations followed thereafter. These were summarized in a
special volume of the Journal of Geophysical Research (Mitchell 1994).
There was a 10 year gap between 1986 and 1996 before the next ocean color
sensor, the short-lived Ocean Color and Temperature Sensor (OCTS, Nov 1996–
June 1997), was carried aboard the Japanese Midori satellite. Soon thereafter, the
Sea-viewing Wide Field-of-view Sensor (SeaWiFS, August 1997–December
2010) was launched onboard the Orbview-2 satellite, ushering in the modern era of
continuous space-based ocean color observations (Hooker et al. 1992; McClain
2009). Since then, many follow-on ocean color sensors have been launched into
space by the U.S. NASA, the European Space Agency (ESA), and other international agencies. These include the Moderate Resolution Imaging Spectroradiometer (MODIS, 1999–present for Terra and 2002–present for Aqua, NASA), the
Medium Resolution Imaging Spectrometer (MERIS, 2002–2012, ESA), the Ocean
Color Monitor (OCM-1, 1999–present; OCM-2, 2009–present, India), and more
recently, the Geostationary Ocean Color Imager (GOCI, 2010–present, South
Korea) and the Visible Infrared Imager Radiometer Suite (VIIRS, 2011–present,
NASA and NOAA). For a reference, Table 7.1 lists the characteristics of several
ocean color sensors commonly used by the scientific community. After proper
calibration and validation, the frequent and synoptic observations of the global and
regional oceans from these large-swath satellite observations have been used in a
variety of research and applications well beyond the original scope of mapping
ocean chlorophyll. For example, ocean color observations have been used to study
the ocean’s biogeochemistry and primary production, to trace ocean circulation
172
C. Hu and J. Campbell