Proceedings Article | 5 October 2007
KEYWORDS: Absorption, Remote sensing, Water, MODIS, Satellites, Optical properties, Statistical analysis, Reflectivity, Magnesium, Error analysis
The coastal zone is of enormous importance to the environmental, economic, and social well being of nations. It is
subject to increasing pressures from many sources, including industrial development, urban expansion, the exploitation
of marine resources, and tourism. In order to understand and address the effects of natural and anthropogenic forces in
the Southeastern coastal zone of Brazil, time-series of in-situ and satellite-based environmental observations are being
developed to account for the interconnectivity of processes within the system. In this work, data collected during
December 2004-January 2006 at the ANTARES time series station near Ubatuba, Southeast Brazil (23°44'S and
45°00'W) are analyzed. The data set includes measurements of near-surface chlorophyll-a concentration (CHL),
absorption by particles, detritus, and colored dissolved organic matter (CDOM), and above-water hyperspectral
reflectance. A triangular diagram, based on the relative contribution to spectral absorption of the optically active
constituents, is used to classify the waters, revealing CDOM-dominated Case 2 waters. Seasonal changes in water
composition and optical properties are examined. Applying the OC2v4, OC4v4, and OC3M algorithms to the radiometric
data, after proper spectral integration, the CHL estimates are generally too high compared with fluorometric
determinations, which might be caused by relatively large CDOM absorption at the coastal site.
