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griddap Subset tabledap Make A Graph wms files Title Summary FGDC ISO 19115 Info Background Info RSS Email Institution Dataset ID Profile - R4.x257.230.0016 - DP05_chl - 28.44N, 87.68W - 2017-05-02 The optical absorption spectra from seawater?s particulate and dissolved components can be used to compute the penetration of light to various depths, estimate the proportion of living to non-living particulate matter, assess photosynthetic light availability and the type of phytoplankton present, and to validate satellite or airborne ocean color measurements. Chlorophyll and phaeopigment concentrations are often used to estimate the amount of phytoplankton present, and to allow extrapolation of in situ fluorometric measurements. Water was collected using a Conductivity, Temperature, Depth (CTD) rosette near the surface and from several depths at each sampling station occupied by the DEEPEND cruise DP05 (see GRIIDC dataset R4.x257.226:0014). A variable amount (<1 to 5 l) of this water was filtered through glass-fiber filter pads. The filter pads were stored for subsequent analysis. Some of the filtrate was passed through an additional nylon membrane (0.2 µm) filter, and also retained for shore based analysis. Optical absorption of the particulate material on the filter pads was determined on shore, using the quantitative filter technique (Yentsch, 1962; Kiefer and SooHoo, 1982). The spectral transmission of light (400-800nm) passing through each filter pad was measured, both before and after the phytoplankton pigments are extracted from the particles retained on the filter pad using methanol (Kishino et al., 1985). These techniques allow the optical absorption spectra of the particles in the water to be determined, as well as the proportion of absorption due to pigmented or detrital material. The extraction of pigments allows the chlorophyll a and phaeopigment concentration to be determined fluorometrically using an acidification technique (Holm-Hansen et al., 1965; Holm-Hansen and Riemann, 1978). The filtrate from the at sea filtration is analyzed using a spectrophotometer to determine the absorption spectra (200-800nm) of the colored dissolved material (Colored Dissolved Organic Matter (CDOM)) in the water sample. This data was collected during the same cruise as GRIIDC CTD dataset R4.x257.230:0013.\n\ncdm_data_type = Profile\nVARIABLES:\nprofile (DP05_chl)\nz\ntime (seconds since 1970-01-01T00:00:00Z)\nlatitude (degrees_north)\nlongitude (degrees_east)\n... (10 more variables)\n (external link) University of South Florida / College of Marine Science R4_x257_230_0016_DP05_chl

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