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MOBY, A Radiometric Buoy for Performance Monitoring and Vicarious Calibration of Satellite Ocean Color Sensors: Measurement and Data Analysis ProtocolsThe Marine Optical Buoy (MOBY) is the centerpiece of the primary ocean measurement site for calibration of satellite ocean color sensors based on independent in situ measurements. Since late 1996, the time series of normalized water-leaving radiances L(sub WN)(lambda) determined from the array of radiometric sensors attached to MOBY are the primary basis for the on-orbit calibrations of the USA Sea-viewing Wide Field-of-view Sensor (SeaWiFS), the Japanese Ocean Color and Temperature Sensor (OCTS), the French Polarization Detection Environmental Radiometer (POLDER), the German Modular Optoelectronic Scanner on the Indian Research Satellite (IRS1-MOS), and the USA Moderate Resolution Imaging Spectrometer (MODIS). The MOBY vicarious calibration L(sub WN)(lambda) reference is an essential element in the international effort to develop a global, multi-year time series of consistently calibrated ocean color products using data from a wide variety of independent satellite sensors. A longstanding goal of the SeaWiFS and MODIS (Ocean) Science Teams is to determine satellite-derived L(sub WN)(labda) with a relative combined standard uncertainty of 5 %. Other satellite ocean color projects and the Sensor Intercomparison for Marine Biology and Interdisciplinary Oceanic Studies (SIMBIOS) project have also adopted this goal, at least implicitly. Because water-leaving radiance contributes at most 10 % of the total radiance measured by a satellite sensor above the atmosphere, a 5 % uncertainty in L(sub WN)(lambda) implies a 0.5 % uncertainty in the above-atmosphere radiance measurements. This level of uncertainty can only be approached using vicarious-calibration approaches as described below. In practice, this means that the satellite radiance responsivity is adjusted to achieve the best agreement, in a least-squares sense, for the L(sub WN)(lambda) results determined using the satellite and the independent optical sensors (e.g. MOBY). The end result of this approach is to implicitly absorb unquantified, but systematic, errors in the atmospheric correction, incident solar flux, and satellite sensor calibration into a single correction factor to produce consistency with the in situ data.
Document ID
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Clark, Dennis K.
(National Environmental Satellite Service Suitland, MD, United States)
Yarbrough, Mark A.
(Moss Landing Marine Labs. CA, United States)
Feinholz, Mike
(Moss Landing Marine Labs. CA, United States)
Flora, Stephanie
(Moss Landing Marine Labs. CA, United States)
Broenkow, William
(Moss Landing Marine Labs. CA, United States)
Kim, Yong Sung
(Data Systems Technologies, Inc. Rockville, MD, United States)
Johnson, B. Carol
(National Inst. of Standards and Technology Gaithersburg, MD, United States)
Brown, Steven W.
(National Inst. of Standards and Technology Gaithersburg, MD, United States)
Yuen, Marilyn
(National Environmental Satellite Service Suitland, MD, United States)
Mueller, James L.
(San Diego State Univ. San Diego, CA, United States)
Date Acquired
September 7, 2013
Publication Date
April 1, 2003
Publication Information
Publication: Ocean Optics Protocols for Satellite Ocean Color Sensor Validation. Volume 6: Special Topics in Ocean Optics Protocols and Appendices
Subject Category
Instrumentation And Photography
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.
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