Chapter 2
Satellite Water Colour Observations
in African Seas
Jim Gower and Stephanie King
Abstract Satellite water colour image data can now be used to show the spatial
patterns of coastal and ocean water properties, especially surface chlorophyll concentration, on scales covering from kilometers to the entire globe. The repeated coverage
shows weekly, seasonal and longer term variability, and provides a unique resource
for regions where in-situ data sources are scarce, as is the case for most waters round
the continent of Africa. Easy access to extensive data sets of satellite-measured
chlorophyll, characterized through the average absorption and scattering properties
of phytoplankton, and through natural fluorescence, are now available from Goddard
Interactive Online Visualization ANd aNalysis Infrastructure (GIOVANNI), developed by the US National Aeronautics and Space Administration (NASA), and other
data systems. In addition, data such as the MCI index from MEdium Resolution
Imaging Spectrometer (MERIS), available by the European Space Agency (ESA),
derived using spectral bands near 700 nm in the near-infrared part of the spectrum,
provide further information on blooms and aquatic vegetation. We present here results of satellite observations of various African seas, showing some of the variety
of observations and time series results possible.
2.1 Satellite Ocean Colour Data
“Satellite water colour data” refers to the relatively low (typically 1 km) spatial
resolution optical image data of oceans and coastal waters provided by specialized
satellite imagers. Data are collected in carefully chosen spectral bands, typically
10–20 nm wide. Land imaging usually requires higher spatial resolution (to 30 m
or less) and often uses broad spectral bands (100 nm) or even the full available
optical window (panchromatic images). Important requirements for water imaging
are frequent repetition, with the satellites providing near-daily coverage, though
frequently interrupted by cloud, and precise short and long-term calibration.
The US ocean colour satellite sensors Coastal Zone Color Scanner (CZCS), Seaviewing Wide Field of view Scanner (SeaWiFS), MODerate Resolution Imaging
J. Gower () · S. King
Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, BC V8L 4B2, Canada
e-mail: Jim.Gower@dfo-mpo.gc.ca
V. Barale, M. Gade (eds.), Remote Sensing of the African Seas,
31
DOI 10.1007/978-94-017-8008-7_2,
© Springer Science+Business Media Dordrecht 2014
Satellite Water Colour Observations
in African Seas
Jim Gower and Stephanie King
Abstract Satellite water colour image data can now be used to show the spatial
patterns of coastal and ocean water properties, especially surface chlorophyll concentration, on scales covering from kilometers to the entire globe. The repeated coverage
shows weekly, seasonal and longer term variability, and provides a unique resource
for regions where in-situ data sources are scarce, as is the case for most waters round
the continent of Africa. Easy access to extensive data sets of satellite-measured
chlorophyll, characterized through the average absorption and scattering properties
of phytoplankton, and through natural fluorescence, are now available from Goddard
Interactive Online Visualization ANd aNalysis Infrastructure (GIOVANNI), developed by the US National Aeronautics and Space Administration (NASA), and other
data systems. In addition, data such as the MCI index from MEdium Resolution
Imaging Spectrometer (MERIS), available by the European Space Agency (ESA),
derived using spectral bands near 700 nm in the near-infrared part of the spectrum,
provide further information on blooms and aquatic vegetation. We present here results of satellite observations of various African seas, showing some of the variety
of observations and time series results possible.
2.1 Satellite Ocean Colour Data
“Satellite water colour data” refers to the relatively low (typically 1 km) spatial
resolution optical image data of oceans and coastal waters provided by specialized
satellite imagers. Data are collected in carefully chosen spectral bands, typically
10–20 nm wide. Land imaging usually requires higher spatial resolution (to 30 m
or less) and often uses broad spectral bands (100 nm) or even the full available
optical window (panchromatic images). Important requirements for water imaging
are frequent repetition, with the satellites providing near-daily coverage, though
frequently interrupted by cloud, and precise short and long-term calibration.
The US ocean colour satellite sensors Coastal Zone Color Scanner (CZCS), Seaviewing Wide Field of view Scanner (SeaWiFS), MODerate Resolution Imaging
J. Gower () · S. King
Institute of Ocean Sciences, Fisheries and Oceans Canada, Sidney, BC V8L 4B2, Canada
e-mail: Jim.Gower@dfo-mpo.gc.ca
V. Barale, M. Gade (eds.), Remote Sensing of the African Seas,
31
DOI 10.1007/978-94-017-8008-7_2,
© Springer Science+Business Media Dordrecht 2014