A team led at NASA's Goddard Space Flight Center in Greenbelt, Md., has developed an instrument capable of observing ocean color during normal sunlight conditions and under moonlight — a first-ever capability that will allow scientists to monitor the health and chemistry of the planet’s oceans literally around the clock.
The prototype Ocean Color Underwater Low Light Advanced Radiometer (OCULLAR) has shown in field testing that it can measure ocean color under low-light conditions across multiple wavelength bands, from the ultraviolet to the near-infrared. In contrast, current remote-sensing instruments can obtain measurements — based on electromagnetic energy emitted by the sun, transmitted through the atmosphere, reflected off Earth’s surface, or upwelled from water masses — only during daylight hours, said Principal Investigator Stan Hooker.
Of particular interest to scientists studying ocean color is phytoplankton, the microscopic ocean plants that form the base of the oceanic food web. The tiny plants use sunlight and carbon dioxide to produce organic carbon. This process, called photosynthesis, is possible because plants contain chlorophyll, green-colored compounds that trap the energy from sunlight.
Because different types of phytoplankton contain different kinds of chlorophyll, measuring the color of a particular area allows scientists to estimate the amount and general type of phytoplankton there. Since phytoplankton also depend on specific conditions for growth, they frequently become the first to be affected by pollution or some other change in their environment.
Until now, however, obtaining these measurements was limited to daylight hours and only during the spring, summer and fall months in the polar regions — a problem Hooker sought to correct with OCULLAR. The successful OCULLAR demonstration leads the way to anticipated commercialization and creates a new capability for oceanographers, climate scientists, and others interested in quantifying, understanding, and monitoring the biological productivity of oceans, coastal areas, and inland waters.
Also: Learn about a Data Assimilation System for Coastal Ocean Prediction.