The colour of large water bodies is an important indicator of ocean health. Clean ocean water absorbs longer wavelengths of light (reds) meaning that the shorter wavelengths are reflected and that is why the sea usually looks blue. The precise spectral signature of the ocean, of which the notion of colour is a crude summary, depends on many things, including the incident solar radiation, the depth of the water where a colour measurements is made, and most importantly the microscopic particles suspended or moving in the water. Deviations from clean water can be a proxy for the health of the water ecosystem. Currently regular measurements of ocean colour (using simple, but uncalibrated, colour cameras) are made by crews on tourist vessels plying the Hauraki Gulf.
The purpose of this project is to design and build a sky-corrected spectrometer for measuring the spectral signature of water. Sky-correction is required because naive spectral measurements do not account for the incident solar illumination. The reflectance function of the ocean layers is independent of the spectrum of the illumination so this must be removed as part of the calibration and measurement process.
The project will require students interested in optics, analog and digital electronics, digital signal processing, and embedded software development.
The outcomes of this project include (a) a prototype hardware system for simultaneously acquiring the spectra of the ocean and sky, (b) a calibration measurement and correction procedure, (c) control and signal processing software, and (d) an evaluation of the accuracy and feasibility of the system.
Lab allocations have not been finalised