358
S. Sathyendranath and T. Platt
phytoplankton types. The influence of the atmosphere will ensure that ocean-colour
studies would always have to deal with a small signal in a high noise environment.
The non-linearity in the relationships between the radiometric quantities derived
from satellites and the in-water constituents of interest will always be a problem to
contend with.
The technological developments go hand in hand with innovative products. On
the other hand, many of the secondary products depend on the availability of long
time series of standardised products. So there will always be demands for sustained,
long-term, consistent observations as well as for technological advancement and
development of novel products. In a world with limited resources, some of these
requirements may at times be in conflict with each other, and ambitions to push
the limits of what is possible technologically would have to be balanced against the
need to create the longest possible, climate-quality data records for addressing key
issues facing us today, such as climate change.
In 1921 Sir C.V. Raman, in an article in Nature, argued that it was optical processes in the ocean, rather than the reflection of sun light, that gave sea water its
characteristic blue colour (Raman, 1921), refuting the earlier suggestion by Lord
Rayleigh that sea was blue due to reflection of the blue of the sky. It then appeared
a solved problem, and of not much further scientific interest, until the influence
of phytoplankton on the colour of the sea was articulated (e.g., Morel and Prieur,
1977). That led to the launch of the first ocean-colour sensor, the Coastal Zone
Colour Scanner. Since then, the biological applications have been the driver for
ocean-colour research. Yet, it has always been physics that drives the theoretical
work to understand the optical processes responsible for variations in ocean colour.
Interestingly, Raman came to the forefront again when the importance of Raman
scattering in determining the marine light field was discovered well after the launch
of the CZCS (e.g., Stavn and Weidemann, 1988). Ocean-colour science is interdisciplinary in nature, and it is the constant interplay between physics and biology that
has made ocean colour a fascinating subject of study. It will surely remain so for
several more decades to come.
Acknowledgements This work was supported by the Canadian Space Agency through its GRIP
and EOPI programmes, and by NERC (UK) through its 2025 and NCEO programmes. We thank
Vittorio Barale for all his patience as the editor, and Nicolas Hoepffner for his helpful comments
on an earlier version of the manuscript.
References
Devred E, Sathyendranath S, Platt T (2007) Delineation of ecological provinces using ocean colour
radiometry. Mar Ecol Prog Ser 346:1–13
Doerffer R, Schiller H (1998) Determination of Case 2 water constituents using radiative transfer simulation and its inversion by neural networks. In: Ackleson SG, Campbell J (eds.)
Proceedings of the Ocean Optics XIV, Office of Naval Research, Washington, DC
GCOS (2004) Implementation plan for the global observing system for climate in support of
UNFCCC. GCOS-92, WMO/TD No 1219
IOCCG (1999) Status and plans for satellite ocean-colour missions: considerations for complementary missions. In: Yoder JA (ed.) Reports of the International Ocean-Colour Coordinating
Group, No. 2, IOCCG, Dartmouth, Canada
S. Sathyendranath and T. Platt
phytoplankton types. The influence of the atmosphere will ensure that ocean-colour
studies would always have to deal with a small signal in a high noise environment.
The non-linearity in the relationships between the radiometric quantities derived
from satellites and the in-water constituents of interest will always be a problem to
contend with.
The technological developments go hand in hand with innovative products. On
the other hand, many of the secondary products depend on the availability of long
time series of standardised products. So there will always be demands for sustained,
long-term, consistent observations as well as for technological advancement and
development of novel products. In a world with limited resources, some of these
requirements may at times be in conflict with each other, and ambitions to push
the limits of what is possible technologically would have to be balanced against the
need to create the longest possible, climate-quality data records for addressing key
issues facing us today, such as climate change.
In 1921 Sir C.V. Raman, in an article in Nature, argued that it was optical processes in the ocean, rather than the reflection of sun light, that gave sea water its
characteristic blue colour (Raman, 1921), refuting the earlier suggestion by Lord
Rayleigh that sea was blue due to reflection of the blue of the sky. It then appeared
a solved problem, and of not much further scientific interest, until the influence
of phytoplankton on the colour of the sea was articulated (e.g., Morel and Prieur,
1977). That led to the launch of the first ocean-colour sensor, the Coastal Zone
Colour Scanner. Since then, the biological applications have been the driver for
ocean-colour research. Yet, it has always been physics that drives the theoretical
work to understand the optical processes responsible for variations in ocean colour.
Interestingly, Raman came to the forefront again when the importance of Raman
scattering in determining the marine light field was discovered well after the launch
of the CZCS (e.g., Stavn and Weidemann, 1988). Ocean-colour science is interdisciplinary in nature, and it is the constant interplay between physics and biology that
has made ocean colour a fascinating subject of study. It will surely remain so for
several more decades to come.
Acknowledgements This work was supported by the Canadian Space Agency through its GRIP
and EOPI programmes, and by NERC (UK) through its 2025 and NCEO programmes. We thank
Vittorio Barale for all his patience as the editor, and Nicolas Hoepffner for his helpful comments
on an earlier version of the manuscript.
References
Devred E, Sathyendranath S, Platt T (2007) Delineation of ecological provinces using ocean colour
radiometry. Mar Ecol Prog Ser 346:1–13
Doerffer R, Schiller H (1998) Determination of Case 2 water constituents using radiative transfer simulation and its inversion by neural networks. In: Ackleson SG, Campbell J (eds.)
Proceedings of the Ocean Optics XIV, Office of Naval Research, Washington, DC
GCOS (2004) Implementation plan for the global observing system for climate in support of
UNFCCC. GCOS-92, WMO/TD No 1219
IOCCG (1999) Status and plans for satellite ocean-colour missions: considerations for complementary missions. In: Yoder JA (ed.) Reports of the International Ocean-Colour Coordinating
Group, No. 2, IOCCG, Dartmouth, Canada