69
of primary production (Koblentz-Mishke et ai., 1970) that reveal a pattern of distribution
remarkably similar to the (admittedly much more colourful, glossy and spectacular) composite
images of chlorophyll concentration produced by technicians of the Goddard Space Flight
Center and the University of Miami (USA). In these early reports, geographic differences
were ascribed to variability in solar radiation, upwelling conditions along continents, and
monsoonal wind direction, and along fronts. Also, features such as the development of the
spring bloom in the North Atlantic had been identified in the sixties by the CPR survey
(Glover, 1967).
Other conventional techniques, based on compilations of nutrient depletion, light
measurements, and primary production estimated with Steemann-Nielsen's 14C method in seas
and oceans allover the world, have been used by Berger et ai. (1987) to reveal globe-wide
patterns of phytoplankton distribution and productivity. However, CZCS pictures are
extremely detailed geographically, and, even more importantly, near-synoptic over enormous
areas. Moreover, the frequency of observations of large regions inaccessible by other means
(especially ships) is unique. Time series of CZCS images have revealed that the dynamics of
the pelagic ecosystem are much greater than expected, and governed to a large extent by
physical forcing. Conversely, physical oceanographers can use the complicated patterns of
pigment distribution as markers of small-scale and large-scale water movements (Holligan,
this volume). A major disadvantage of the CZCS was that the signal due to the presence of
phytoplankton cannot be distinguished from the signal due to the abiotic light absorption
component. In neritic regions, much light is absorbed by Gilvin (Geibstoff or yellow
substance) and particulate detritus, and absorption by phytoplankton pigments in such areas
is relatively insignificant at most wavelength ranges in the visible part of the spectrum at the
4 spectral bands (443, 520, 550 and 670 mm) that are used for the CZCS images. The
persistent chlorophyll abundance in the shallow North Sea throughout the year on CZCS series
(Fig. 5) is not in agreement with Seatruth observations (Fig. 1), and merely reflects
non-phytoplanktonic detrital suspended matter that may become particularly dense after winter
storms. A successor to CZCS, SeaWiFS, which uses twice the number of spectral bands and
much higher radiometric sensitivity in order to allow discrimination between phytoplankton
and detritus, possibly even between different algal groups absorbing light at different
bands/wavelengths, will be launched in 1992. Another ocean color sensor will be on Japan's
space agency NASDA's ADEOS satellite starting in 1996. Images derived from NOAA-n
satellites and A VHRR will continue to provide distribution maps of coccolithophorids, a group
of algae that is of major importance in the global CO2 cycle, which scatter light intensely
when present in blooms (milky waters: Ackleson et aI., 1988).
of primary production (Koblentz-Mishke et ai., 1970) that reveal a pattern of distribution
remarkably similar to the (admittedly much more colourful, glossy and spectacular) composite
images of chlorophyll concentration produced by technicians of the Goddard Space Flight
Center and the University of Miami (USA). In these early reports, geographic differences
were ascribed to variability in solar radiation, upwelling conditions along continents, and
monsoonal wind direction, and along fronts. Also, features such as the development of the
spring bloom in the North Atlantic had been identified in the sixties by the CPR survey
(Glover, 1967).
Other conventional techniques, based on compilations of nutrient depletion, light
measurements, and primary production estimated with Steemann-Nielsen's 14C method in seas
and oceans allover the world, have been used by Berger et ai. (1987) to reveal globe-wide
patterns of phytoplankton distribution and productivity. However, CZCS pictures are
extremely detailed geographically, and, even more importantly, near-synoptic over enormous
areas. Moreover, the frequency of observations of large regions inaccessible by other means
(especially ships) is unique. Time series of CZCS images have revealed that the dynamics of
the pelagic ecosystem are much greater than expected, and governed to a large extent by
physical forcing. Conversely, physical oceanographers can use the complicated patterns of
pigment distribution as markers of small-scale and large-scale water movements (Holligan,
this volume). A major disadvantage of the CZCS was that the signal due to the presence of
phytoplankton cannot be distinguished from the signal due to the abiotic light absorption
component. In neritic regions, much light is absorbed by Gilvin (Geibstoff or yellow
substance) and particulate detritus, and absorption by phytoplankton pigments in such areas
is relatively insignificant at most wavelength ranges in the visible part of the spectrum at the
4 spectral bands (443, 520, 550 and 670 mm) that are used for the CZCS images. The
persistent chlorophyll abundance in the shallow North Sea throughout the year on CZCS series
(Fig. 5) is not in agreement with Seatruth observations (Fig. 1), and merely reflects
non-phytoplanktonic detrital suspended matter that may become particularly dense after winter
storms. A successor to CZCS, SeaWiFS, which uses twice the number of spectral bands and
much higher radiometric sensitivity in order to allow discrimination between phytoplankton
and detritus, possibly even between different algal groups absorbing light at different
bands/wavelengths, will be launched in 1992. Another ocean color sensor will be on Japan's
space agency NASDA's ADEOS satellite starting in 1996. Images derived from NOAA-n
satellites and A VHRR will continue to provide distribution maps of coccolithophorids, a group
of algae that is of major importance in the global CO2 cycle, which scatter light intensely
when present in blooms (milky waters: Ackleson et aI., 1988).