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An Instrument for In Situ Measuring the Volume Scattering Function of Water: Design, Calibration and Primary Experiments
State Key Laboratory of Oceanography in the Tropics, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
South China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou 510300, China
* Author to whom correspondence should be addressed.
Received: 29 February 2012; in revised form: 29 March 2012 / Accepted: 30 March 2012 / Published: 10 April 2012
Abstract: The optical volume scattering function (VSF) of seawater is a fundamental property used in the calculation of radiative transfer for applications in the study of the upper-ocean heat balance, the photosynthetic productivity of the ocean, and the chemical transformation of photoreactive compounds. A new instrument to simultaneously measure the VSF in seven directions between 20° to 160°, the attenuation coefficient, and the depth of water is presented. The instrument is self-contained and can be automatically controlled by the depth under water. The self-contained data can be easily downloaded by an ultra-short-wave communication system. A calibration test was performed in the laboratory based on precise estimation of the scattering volume and optical radiometric calibration of the detectors. The measurement error of the VSF measurement instrument has been estimated in the laboratory based on the Mie theory, and the average error is less than 12%. The instrument was used to measure and analyze the variation characteristics of the VSF with angle, depth and water quality in Daya Bay for the first time. From these in situ data, we have found that the phase functions proposed by Fournier-Forand, measured by Petzold in San Diego Harbor and Sokolov in Black Sea do not fit with our measurements in Daya. These discrepancies could manly due to high proportion of suspended calcium carbonate mineral-like particles with high refractive index in Daya Bay.
Keywords: ocean optics; scattering measurements; array detection; calibration test; in-field measurement; scattering volume; optical radiometric calibration
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Li, C.; Cao, W.; Yu, J.; Ke, T.; Lu, G.; Yang, Y.; Guo, C. An Instrument for In Situ Measuring the Volume Scattering Function of Water: Design, Calibration and Primary Experiments. Sensors 2012, 12, 4514-4533.
Li C, Cao W, Yu J, Ke T, Lu G, Yang Y, Guo C. An Instrument for In Situ Measuring the Volume Scattering Function of Water: Design, Calibration and Primary Experiments. Sensors. 2012; 12(4):4514-4533.
Li, Cai; Cao, Wenxi; Yu, Jing; Ke, Tiancun; Lu, Guixin; Yang, Yuezhong; Guo, Chaoying. 2012. "An Instrument for In Situ Measuring the Volume Scattering Function of Water: Design, Calibration and Primary Experiments." Sensors 12, no. 4: 4514-4533.