Search results | Digital Commons of Moss Landing Marine Laboratories

Title: Stray light correction of the marine optical system,
Description: The Marine Optical System is a spectrograph-based sensor used on the Marine Optical Buoy for the vicarious calibration of ocean color satellite sensors. It is also deployed from ships in instruments used to develop bio-optical algorithms that relate the optical properties of the ocean to its biological content. In this work, an algorithm is applied to correct the response of the Marine Optical System for scattered, or improperly imaged, light in the system. The algorithm, based on the measured response of the system to a series of monochromatic excitation sources, reduces the effects of scattered light on the measured source by one to two orders of magnitude. Implications for the vicarious calibration of satellite ocean color sensors and the development of bio-optical algorithms are described. The algorithm is a one-dimensional point spread correction algorithm, generally applicable to nonimaging sensors, but can in principle be extended to higher dimensions for imaging systems. © 2009 American Meteorological Society., Cited By (since 1996):6, Oceanography, CODEN: JAOTE, , , Downloaded from: journals.ametsoc.org/doi/pdf/10.../2008JTECHO597.1 (16 June 2014).
Author: Feinholz, Flora, Yarbrough, Lykke, Brown, Johnson, Clark
Date: 2009-01-01T00:00:00Z

Title: The Marine Optical Buoy (MOBY) radiometric calibration and uncertainty budget for ocean color satellite sensor vicarious calibration,
Description: For the past decade, the Marine Optical Buoy (MOBY), an autonomous radiometric buoy stationed in the waters off Lanai, Hawaii, has been the primary in-water oceanic observatory for the vicarious calibration of U. S. satellite ocean color sensors, including the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) and the Moderate Resolution Imaging Spectrometer (MODIS) instruments on the National Aeronautics and Space Administration's (NASA's) Terra and Aqua satellites. The MOBY vicarious calibration of these sensors supports international efforts to develop a global, multi-year time series of consistently calibrated ocean color data products. A critical component of the MOBY program is establishing radiometric traceability to the International System of Units (SI) through standards provided by the U. S. National Institute of Standards and Technology (NIST). A detailed uncertainty budget is a core component of traceable metrology. We present the MOBY uncertainty budget for up-welling radiance and discuss approaches in new instrumentation to reduce the uncertainties in in situ water-leaving radiance measurements., Cited By (since 1996):10, Oceanography, Art. No.: 67441M, CODEN: PSISD, ,
Author: Brown, Flora, Feinholz, Yarbrough, Houlihan, Peters, Yong, Mueller, Johnson, Clark
Date: 2007-01-01T00:00:00Z

Title: Ocean optics protocols for satellite ocean color semsor validation, revision 4, Volume VI: Special topics in ocean protocols and appendices,
Description: , , ,
Author: Mueller, Clark, Kuwahara, Lazin, Brown, Fargion, Yarbrough, Feinholz, Flora, Broenkow, Kim, Johnson, Yuen, Strutton, Dickey, Abbott, Letelier, Lewis, McLean, Chavez, Barnard, Morrison, Subramaniam, Manov, Zheng, Harding Jr., Barnes, Lykke
Date: 2003-01-01T00:00:00Z

Title: Simultaneous measurement of up-welling spectral radiance using a fiber-coupled CCD spectrograph,
Description: Determination of the water-leaving spectral radiance using in-water instrumentation requires measurements of the upwelling spectral radiance (L u) at several depths. If these measurements are separated in time, changes in the measurement conditions result in increased variance in the results. A prototype simultaneous multi-track system was developed to assess the potential reduction in the Type A uncertainty in single set, normalized water-leaving radiance achievable if the data were acquired simultaneously. The prototype system employed a spectrograph and multi-track fiber-coupled CCD-detector; in situ in-water tests were performed with the prototype system fiber-coupled to a small buoy. The experiments demonstrate the utility of multi-channel simultaneous data acquisition for in-water measurement applications. An example of the potential impact for tracking abrupt responsivity changes in satellite ocean color sensors using these types of instruments as well as for the satellite vicarious calibration is given., Cited By (since 1996):1, Oceanography, Art. No.: 66800J, CODEN: PSISD, ,
Author: Yarbrough, Flora, Feinholz, Houlihan, Kim, Brown, Johnson, Voss, Clark
Date: 2007-01-01T00:00:00Z

Title: An example crossover experiment for testing new vicarious calibration techniques for satellite ocean color radiometry,
Description: Vicarious calibration of ocean color satellites involves the use of accurate surface measurements of waterleaving radiance to update and improve the system calibration of ocean color satellite sensors. An experiment was performed to compare a free-fall technique with the established Marine Optical Buoy (MOBY) measurement. It was found in the laboratory that the radiance and irradiance instruments compared well within their estimated uncertainties for various spectral sources. The spectrally averaged differences between the National Institute of Standards and Technology (NIST) values for the sources and the instruments were<2.5% for the radiance sensors and<1.5% for the irradiance sensors. In the field, the sensors measuring the above-surface downwelling irradiance performed nearly as well as they had in the laboratory, with an average difference of<2%.While the water-leaving radiance L w calculated from each instrument agreed in almost all cases within the combined instrument uncertainties (approximately 7%), there was a relative bias between the two instrument classes/techniques that varied spectrally. The spectrally averaged (400-600 nm) difference between the two instrument classes/techniques was 3.1%. However, the spectral variation resulted in the freefall instruments being 0.2% lower at 450 nm and 5.9% higher at 550 nm. Based on the analysis of one matchup, the bias in L w was similar to that observed for L u(1 m) with both systems, indicating the difference did not come from propagating L u(1 m) to L w. © 2010 American Meteorological Society., Cited By (since 1996):6, Oceanography, CODEN: JAOTE, ,
Author: Voss, Mclean, Lewis, Johnson, Flora, Feinholz, Yarbrough, Trees, Twardowski, Clark
Date: 2010-01-01T00:00:00Z

Title: Validation of ADEOS-II GLI ocean color products using in-situ observations,
Description: The Global Imager (GLI) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) made global observations from 2 April 2003 to 24 October 2003. In cooperation with several institutes and scientists, we obtained quality controlled match-ups between GLI products and in-situ data, 116 for chlorophyll-a concentration (CHLA), 249 for normalized water-leaving radiance (nLw) at 443 nm, and 201 for aerosol optical thickness at 865 nm (Tau_865) and Angstrom exponent between 520 and 865 nm (Angstrom). We evaluated the GLI ocean color products and investigated the causes of errors using the match-ups. The median absolute percentage differences (MedPD) between GLI and in-situ data were 14.1-35.7% for nLws at 380-565 nm, 52.5-74.8% nLws at 625-680 nm, 47.6% for Tau_865, 46.2% for Angstrom, and 46.6% for CHLA, values that are comparable to the ocean-color products of other sensors. We found that some errors in GLI products are correlated with observational conditions; nLw values were underestimated when nLw at 680 nm was high, CHLA was underestimated in absorptive aerosol conditions, and Tau_865 was overestimated in sunglint regions. The error correlations indicate that we need to improve the retrievals of the optical properties of absorptive aerosols and seawater and sea surface reflection for further applications, including coastal monitoring and the combined use of products from multiple sensors. © The Oceanographic Society of Japan/TERRAPUB/Springer 2006., Cited By (since 1996):9, ,
Author: Murakami, Sasaoka, Hosoda, Fukushima, Toratani, Frouin, Mitchell, Kahru, Deschamps, Clark, Flora, Kishino, Saitoh, Asanuma, Tanaka, Sasaki, Yokouchi, Kiyomoto, Saito, Dupouy, Siripong, Matsumura, Ishizaka
Date: 2006-01-01T00:00:00Z

Title: Stray light correction algorithm for multichannel hyperspectral spectrographs,
Description: An algorithm is presented that corrects a multichannel fiber-coupled spectrograph for stray or scattered light within the system. The efficacy of the algorithm is evaluated based on a series of validation measurements of sources with different spectral distributions. This is the first application of a scattered-light correction algorithm to a multichannel hyperspectral spectrograph. The algorithm, based on characterization measurements using a tunable laser system, can be extended to correct for finite point-spread response in imaging systems. © 2012 Optical Society of America., Cited By (since 1996):1, Oceanography, CODEN: APOPA, ,
Author: Feinholz, Flora, Brown, Zong, Lykke, Yarbrough, Johnson, Clark
Date: 2012-01-01T00:00:00Z

Title: Results in coastal waters with high resolution in situ spectral radiometry: The Marine Optical System ROV,
Description: The water-leaving spectral radiance is a basic ocean color remote sensing parameters required for the vicarious calibration. Determination of water-leaving spectral radiance using in-water radiometry requires measurements of the upwelling spectral radiance at several depths. The Marine Optical System (MOS) Remotely Operated Vehicle (ROV) is a portable, fiber-coupled, high-resolution spectroradiometer system with spectral coverage from 340 nm to 960 nm. MOS was developed at the same time as the Marine Optical Buoy (MOBY) spectrometer system and is optically identical except that it is configured as a profiling instrument. Concerns with instrument self-shadowing because of the large exterior dimensions of the MOS underwater housing led to adapting MOS and ROV technology. This system provides for measurement of the near-surface upwelled spectral radiance while minimizing the effects of shadowing. A major advantage of this configuration is that the ROV provides the capability to acquire measurements 5 cm to 10 cm below the water surface and is capable of very accurate depth control (1cm) allowing for high vertical resolution observations within the very near-surface. We describe the integrated system and its characterization and calibration. Initial measurements and results from observations of coral reefs in Kaneohe Bay, Oahu, extremely turbid waters in the Chesapeake Bay, Maryland, and in Case 1 waters off Southern Oahu, Hawaii are presented., , ,
Author: Yarbrough, Feinholz, Flora, Houlihan, Johnson, Kim, Murphy, Ondrusek, Clark
Date: 2007-01-01T00:00:00Z

Title: Stray-light correction algorithm for spectrographs,
Description: In this paper, we describe an algorithm to correct a spectrograph's response for stray light. Two recursion relations are developed: one to correct the system response when measuring broad-band calibration sources, and a second to correct the response when measuring sources of unknown radiance. The algorithm requires a detailed understanding of the effect of stray light in the spectrograph on the instrument's response. Using tunable laser sources, a dual spectrograph instrument designed to measure the up-welling radiance in the ocean was characterized for stray light. A stray-light correction algorithm was developed, based on the results of these measurements. The instrument's response was corrected for stray light, and the effects on measured up-welling in-water radiance were evaluated., Cited By (since 1996):27, Oceanography, CODEN: MTRGA, ,
Author: Brown, Johnson, Feinholz, Yarbrough, Flora, Lykke, Clark
Date: 2003-01-01T00:00:00Z