A unique NIST tabletop-sized instrument, called the "traveling SIRCUS" (a miniature version of the agency's Spectral Irradiance and Radiance Calibrations with Uniform Sources facility), was transported to Hawaii last year to calibrate the Marine Optical Buoy systems (known as MOBY) that measure the color and magnitude of light reflected from and within the ocean. Data from these systems are used to calibrate satellite-borne color mapping instruments.
Ocean color is important in climate research because variations in the visible light spectrum reflect the concentration of microscopic marine plants, which utilize carbon dioxide from the ocean/atmosphere system for photosynthesis. These phytoplankton absorb blue light and reflect predominantly green light, whereas water reflects predominantly blue. The satellite observations are used to produce global assays of biomass and carbon production in the world's oceans.
The laser-based traveling SIRCUS helped correct errors in the buoy's measurements.
The corrections are having an impact on scientists' calculations of the biomass and carbon concentrations present in the oceans, which will provide a more accurate understanding of Earth's carbon balance and its effect on climate.