Remote sensing of water parameters in Madura Bay
Amann, V.; Doerffer, R.; Helbig, H.; Kadri, T.M.; van der Piepen, H.; van der Piepen, J.S.; Soejoeti, Z. (1989). Remote sensing of water parameters in Madura Bay. Neth. J. Sea Res. 23(4): 473-482
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, more
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| Authors | | Top |
- Amann, V.
- Doerffer, R.
- Helbig, H.
- Kadri, T.M.
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- van der Piepen, H.
- van der Piepen, J.S.
- Soejoeti, Z.
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| Abstract |
During the Madura Bay Remote Sensing Experiment, which was conducted as part of the Snellius-II Expedition in August, 1984, space-borne, air-borne and ship-borne radiometric data were collected. They have been analysed in terms of chlorophyll, suspended matter, yellow substance and sea-surface temperature to map the distribution patterns and temporal variability of different water masses. A general correlation analysis between ship-borne radiance measurements and biochemical data (sea truth) indicates that the dominant factors which determine the reflectance spectra are the total amount of scattering and absorbing substances in the water, sun and sky glitter, and the chlorophyll and phaeophytin concentration. For a coastal area strongly influenced by river run-off , the chlorophyll concentration is comparatively low. As a result, the chlorophyll fluorescence is weak, but can still be detected. The blue/green colour ratio and the fluorescence line height along the flight tracks derived from the Ocean Color Radiometer (OCR) over three consecutive days indicate at least three different types of water, viz. clear ocean water in the eastern part of the Bay, mixed water with moderate contents of chlorophyll and suspended matter in the middle and western parts of the Bay and finally estuarine and river water containing large amounts of inorganic and dissolved organic matter near the mouths of Solo and Brantas rivers and in the Strait itself. Distribution patterns change from one day to the next, possibly as a result of tidal effects. Vertical radiation profiles derived from aircraft flights at different altitudes and from modelling the radiative transfer through the atmosphere give an indication of how well ocean colour/chlorophyll fluorescence can be monitored through a typical tropical atmosphere from satellite altitude. Model calculations and comparative measurements show that even the small fluorescence signals (corresponding to a low pigment concentration) can still be detected above the atmosphere, while colour ratios, especially in the blue part of the spectrum, are heavily masked by aerosol and Raleigh scattering and have to be corrected carefully prior to any interpretation. At all wavelengths, upwelling spectra contain a considerable amount of light specularly reflected at the sea surface. |
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