What is Ocean Color?
The "color" of the ocean is determined by the interactions of incident light
with substances or particles present in the water. The most significant
constituents are free-floating photosynthetic organisms (phytoplankton) and
inorganic particulates. Phytoplankton contain chlorophyll, which absorbs light
at blue and red wavelengths and transmits in the green. Particulate matter can
reflect and absorb light, which reduces the clarity (light transmission) of
the water. Substances dissolved in water can also affect its color.
The phrase "ocean color data" refers to accurate measurements of light intensity at visible wavelengths. As ocean color data is related to the presence of the
constituents described above, it may therefore be used to calculate the
concentrations of material in surface ocean waters and the level of biological
activity. Ocean color observations made from Earth orbit allow an oceanographic
viewpoint that is impossible from ship or shore -- a global picture of
biological activity in the world's oceans.
The Ocean Color Time-Series Project
The GES DISC is a partner in the Ocean Color Time-Series Project, a NASA REASoN CAN Project. This project is analyzing and processing CZCS, OCTS, SeaWiFS, and MODIS-Aqua data to create a uniform time-series commencing in 1978 and continuing to present. As part of this Project, the GES DISC provides multiple data sets and visualization capabilities in Giovanni, the GES DISC Online Interactive Visualization and Analysis Infrastructure, and is advancing the use of ocean color data with Giovanni for oceanographic education in the Laboratory for Ocean Color Users (LOCUS).
Ocean Color at the GES DISC -- History of Achievement
The GES DISC, and in its prior incarnation as the DAAC, has been a pioneer in the distribution of ocean color data. The Coastal Zone Color Scanner archive was one of the first instances of a system that provided a visual "browse" preview of remote sensing images to enhance data ordering. The SeaWiFS archive provided data access to this important mission on the first full day of data acquisition in September 1997. The MODIS data system provided full access to a extensive suite of remotely-sensed data products. The DAAC also developed a variety of informational and outreach materials to enhance knowledge, and provided constant support services to users.
Evolution and Change in the 21st Century
As ocean color data analysis has progressed, the NASA Ocean Biology Processing Group (built from the SeaWiFS Project) has undertaken data access and distribution through the Ocean Color Web. This allows ongoing data analysis and data reprocessing activities to be performed concurrently. At the same time, the GES DISC now provides simple and basic ocean color data analysis with Giovanni. Giovanni currently provides an online data analysis environment, offering a unique combination of data visualization and data access to the OBPG data archive. Giovanni is a featured component of the Laboratory for Ocean Color Users (LOCUS).
Questions about ocean color data in Giovanni and general questions about oceanography related to the use of this tool can be sent to GES DISC Help. Questions about ocean color data from historical and current NASA missions may be posted on the Ocean Color Forum.
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Atmos Composition
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