Traceability in Ocean Color: the MOBY Example

Developing and maintaining accurate climate data records on regional and global scales are key objectives of the NOAA Climate Mission Goal. Current climate-relevant satellite ocean remote sensing parameters include sea- surface height, sea-surface temperature, sea-ice, ocean surface winds, and ocean color water-leaving spectral radiance. Many ocean color remote sensing missions, including the Sea-viewing Wide Field-of-View (SeaWiFS) sensor and the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) sensors, have developed a set of protocols for on-orbit sensor characterization and calibration that includes in situ vicarious calibration using the Marine Optical BuoY (MOBY), the primary U.S. facility for vicarious calibration of ocean color satellite sensors. Having just celebrated 10 years of continuous operation, over 8400 MOBY data sets have been acquired and used in the vicarious calibration of these ocean color satellite sensors. In this talk, we present the efforts undertaken by the MOBY team to ensure measurement traceability to the International System of Units (SI). The term traceability in this context has a specific meaning, requiring a full analysis and description of uncertainties and an unbroken chain of calibrations back to an internationally recognized primary standard maintained by a national metrology institute (NMI), in this case the U.S. National Institute of Standards and Technology.