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Downwelling Surface Spectral Irradiance Measurements with the Marine Optical BuoY



Bettye C. Johnson, M Feinholz, S Flora, M Yarbrough, Terrance Houlihan, D Peters, Dennis Clark


The Marine Optical BuoY (MOBY), off the coast of Lanai, Hawaii, has made in situ, in-water up-welling spectral radiance and downwelling surface spectral irradiance measurements since July 1997. The MOBY observatory concept was developed and implemented specifically to serve as the primary in-water oceanic observatory for the vicarious calibration of U. S. satellite ocean color sensors SeaWiFS and MODIS. This required establishment of long term radiometric stability, traceable to national standards, for all measurements. The downwelling surface irradiance measurements are primarily used for reliable determinations of the diffuse attenuation coefficient from the up-welling spectral radiance data. In this paper, we present the preliminary results for the MOBY surface irradiance time series. The MOBY results are hyperspectral, high resolution, and full spectral coverage (340 nm to 955 nm). We describe the calibration and characterization of this data set, and the present status of its uncertainty. The data set is of interest because the results can be spectrally averaged (e.g., photosynthetically active radiation (PAR) response) and studied for trends, a study of interest to the global dimming community because there are very few well-calibrated, long term sites in open ocean environments.
Proceedings Title
Ocean Optics XIX Conference
Conference Dates
October 6-10, 2008
Conference Location
Barga, IT


global dimming, MOBY, radiometry, surface spectral irradiance


Johnson, B. , Feinholz, M. , Flora, S. , Yarbrough, M. , Houlihan, T. , Peters, D. and Clark, D. (2008), Downwelling Surface Spectral Irradiance Measurements with the Marine Optical BuoY, Ocean Optics XIX Conference, Barga, IT (Accessed April 21, 2024)
Created December 31, 2008, Updated February 19, 2017