A new technology instrument system for the in-situ measurement of the optical properties of marine waters in the 400 to 900 nm range is to be developed. The data collected will contribute towards a full understanding of the links between marine water constituent levels and corresponding upwelling radiances measured by remote sensing instruments.
The marine radiometric spectrometer system MARAS has been developed to perform spectral radiometry in the ocean. By simultaneous collection of upwelling and downwelling scalar and vector spectral irradiance the apparent optical properties of a water body can be estimated. The multicollector system has collectors mounted at 2 depths so that it is relatively impervious to changes in the ambient light levels and only requires relative, rather than absolute, calibration of its sensor sensitivities.
The measurements of apparent optical properties are used in an inversion system which has been developed and tested by simulated radiative transfer models and can be shown to yield useful estimates of the inherent absorption and scattering properties of the ocean. The direct effect of ocean constituents on both the measurements themselves, and on the derived apparent and inherent optical properties are demonstrated.
The instrument concept will utilise available off-the-shelf CCD array detectors, associated electronics and frame-grabbing technology. Combined with low numerical aperture fibre optics, these two-dimensional detector systems now offer the ability to simultaneously record target, reference and calibration radiance spectra. Through the use of frame-grabbing and integration techniques, and without sophisticated cooling systems, these detectors can achieve high effective sensitivity. This will allow scope for innovative concepts in the fore-optics design and the data capture and processing software, while removing the requirement for the development of new electronics or recording systems.
Funding SchemeCSC - Cost-sharing contracts