Retrieving in situ particulate absorption spectra in optically clear waters: An example from the Equatorial Pacific
Wayne
Slade, School of Marine Sciences, University of Maine, wayne.slade@gmail.com
Rois
Langner, Bigelow Laboratory for Ocean Sciences, rlangner@bigelow.org
Emmanuel
Boss, School of Marine Sciences, University of Maine, emmanuel.boss@maine.edu
Collin
Roesler, Darling Marine Center, University of Maine, collin.roesler@maine.edu
Michael
Behrenfeld, Department of Botany and Plant Pathology, Oregon State University, mjb@science.oregonstate.edu
(Presenting)
In situ measurements of inherent optical properties in clear open ocean waters brings attention to a number of instrumentation and calibration issues, foremost, that measurements are made relative to pure water. Using a WET Labs ac9 or ac-s, these measurements are difficult when the signal is within the resolution limit of the instrument. Drift in instrument electronics or optics and fouling of optical windows at this resolution can provide further issues affecting precise absorption measurements. Pure water calibrations used to correct these issues are also difficult while at sea and with limited resources. However, by using a WET Labs ac9 configured with a switchable 0.2 mm filter cartridge we can calculate the difference between temporally adjacent filtered and unfiltered observations, producing calibration-independent robust and accurate particulate absorption spectra that are of the same magnitude as the resolution of the instrument.
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