Remote sensing of marine environment: Applied surveillance with focus on optical properties of phytoplankton, coloured organic matter and suspended matter

Abstract

Light from the Sun reaching the Earth and sea surface contains the entire wavelength band from ultraviolet (180-400 nm), visible (400-700 nm) and far into the infrared and radio wave region (>700 nm). The light penetrates into the sea, and gives energy to phytoplankton and macroalgal photosynthesis. The different wavelengths of the light is selectively absorbed by the sea water itself and by different active optical components in the water such as phytoplankton, coloured dissolved organic matter and total suspended matter. The major goal of this study is to elucidate, understand and to predict the behaviour of these optically significant components.

The thesis describes the development, from the start of the harmful algae bloom (HAB) monitoring in Norway (1988) from moored buoys with optical instruments and a HAB observation network along the Norwegian coast, until today (2009) using hyperspectral imagers on different platforms as airplanes, balloons or kites. The use of different platforms such as satellite remote sensing combined with ship-borne water sampling and analyses of chlorophyll a, total suspended matter and turbidity (Ferrybox), the Norwegian HAB observation network and high-performance liquid chromatography (HPLC) pigment analysis of water samples as a classification tool are all combined in this study. The combination of these tools is still available because Norway has an active HAB observation network and functional Ferrybox network mounted on ships of opportunity. In the experiment from 2004 the Ferrybox was mounted on the coastal express vessel Trollfjord.

Hyperspectral techniques are shown to be useful to monitor and forecast phytoplankton and kelp distribution. Methodology for the use of hyperspectral imaging (HI) from airplane to detect kelp forests and HI combined with a microscope for optical fingerprinting of different pigment-groups of micro- and macro algae are demonstrated. The results also show that HI is a valuable tool for local remote sensing, and an extended tool for identification, calibration and validation of remotely sensed ocean colour.