Ocean Color Observations

SS7.01: Optical Properties of Oceanic Case 1 Waters: Still An Issue?
Organizers: André Morel, Laboratoire d'Océanographie de Villefranche, Villefranche-Sur-Mer, France, (morel@obs-vlfr.fr) and Hervé Claustre, Université Pierre et Marie Curie et CNRS, Villefranche-Sur-Mer, France (claustre@obs-vlfr.fr)

Oceanic Case 1 waters are generally considered as a simple two-component system (water + locally created biogenous material), whose optical properties can be indexed on the chlorophyll concentration, [Chl-a]. This assertion is in a first approximation justified, especially when considering the complexity of Case 2 waters. However, the simplicity is fallacious, because a variability inside the biogenous compartment certainly does exist. This variability has been progressively documented, and recent studies show that mean and general relationships used to describe the optical properties in Case 1 waters in relation to [Chl-a] do not strictly apply in certain regions (e.g. Antarctic, Arctic, Mediterranean Sea), or when they roughly apply, distinct nuances are systematically detectable (e.g. in various oligotrophic zones, or seasonally in the same zone). These discrepancies, or nuances, likely originate from biogeochemical differences, including varying pigment composition, varying proportions between the photoautotrophic, the heterotrophic pools, and the biodetritic pool (dissolved as CDOM, or particulate debris); perhaps exogenous (aeolian) inputs, are also responsible for some deviations. Such differences have a direct impact upon the skill of algorithmic schemes in use when processing Ocean Color data, and which are based on mean relationships. It seems timely to review these recent findings, understand the causes of the natural bio-optical variability in Ocean Case 1 waters, to fix the errors associated with the use of mean relationships, and, better, to propose and validate locally adapted relationships and algorithms.

SS7.02: Hyperspectral Signatures of Case 2 Waters
Organizer: Robert Arnone, Naval Research Laboratory (arnone@nrlssc.navy.mil)

The session is aimed at examining coastal processes through the use of hyperspectral ocean color. Understanding how spectral signatures change within the coastal zone provides new abilities to trace coastal changes and water mass movements (such as river plumes and bottom vegetation). Hyperspectral sensing from aircraft and satellite sensors provide new capability for understanding the coastal environment. Recent advances in space / airborne spectroscopy provide new abilities for researchers in addition to coastal managers to monitor coastal regions. Spectral signatures of case 2 water represent a complex interaction of water components and/ or bottom interaction. This session will explore the use of hyperspectral signatures to uncouple the composition of coastal waters. These include the water optical properties of absorption from phytoplankton, CDOM, detritus and scattering by organic / inorganic particles. Additionally, these signatures can be influenced by water depth and bottom type. The session will focus of advanced algorithms for ocean color in case 2 waters and will include methods for atmospheric correction and in water algorithms for biological, geological and optical properties.