THE USE OF MODIS DATA TO DEFINE NATURAL BOUNDARIES AND REGIONS IN THE MARINE WATER COLOUMN

Abstract. This study looks at the elements that define a natural boundary and its marine variant. It then aims to quantify and delimit natural marine boundaries from satellite sea surface temperature and ocean colour imagery. Natural boundaries often have a fuzzy or zonal nature, can be dependent on and independent from the character of the region which they bound, and have temporal characteristics that occur over a variety of temporal scales. Natural marine boundaries have the added complexity of occurring in three dimensions and of being temporally dynamic throughout the water column. A monthly time-series of MODIS satellite imagery from July 2002 to June 2006 was used in this study. The standardised principle component analysis (sPCA) was used to identify the mean state of identifiable natural process and to quantifying a degree of spatio-temporal (seasonal) dichotomy in detected marine processes. Component images from the sPCA provided a spatial representation of marine phenomena, while sPCA loadings indicated the temporal fluxes exhibited in a given component. Classification of significant sPCA components was conducted to derive regional boundaries. Initially, this was performed in an unsupervised manner using an ISO process. Subsequent classified images were then simplified using a combination of dendrograms and knowledge-based examination. A comparison of these results with similarly derived regionalisation showed that the spatio-temporal representations have the potential to further inform marine spatial management regimes. It was also shown that the delimitation of natural phenomena is feasible and can have seasonal dynamics represented.