Absorption modeling in case II waters: the need to distinguish colored dissolved organic matter from nonchlorophyllous particulates

摘要

Abstract: The presented study examines, for substantial datasets in different Case II waters, the variability of the spectral absorption of Non-Chlorophyllous Particles (NCP) and Colored Dissolved Organic Matter (CDOM). The investigation has considered the validity of the currently proposed modeling of the absorption of these tow components as a single variable, in applications to Case II water environments. In order to encompass a broad range of environmental situations in the comparison of NCP and CDOM absorption spectra, two very different sites were selected. The locations investigated were the Southern Baltic Proper and a site in the Northern Adriatic close to the Italian coast. These two regions differ both in their basic oceanographic properties and int heir relative proportions of both space and time, combining a series of seasonal oceanographic campaigns in the Baltic with a complete annual time series of monthly measurements at a fixed point in the Adriatic. The analysis has shown that, in the selected European Case II waters, the observed variability of the spectral absorption of NCP and CDOM, both with respect to each other as well as to the total absorption, are independent. It is therefore suggested that, in the frame of Reflectance modeling in Case II waters, attention must be placed on accounting for NCP an CDOM individually when defining the absorption segment. !15