Hawaii Ocean Time-series (HOT)
in the School of Ocean and Earth Science and Technology at the University of Hawai'i
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Samples for Chlorophyll a (chl a) and pheopigments were collected onto glass fiber filters (Whatman GF/F, 25 mm diameter) and measured fluorometrically on a Turner Designs Model 10-AU flourometer with 100% acetone as the solvent using standard techniques (Strickland and Parsons, 1972). The average precisions during 2015 determined from triplicate analyses are presented in the Table below.
A contour plot of chlorophyll a concentrations measured using standard fluorometric techniques from 0 to 200 dbar during 1988-2015 is shown in Figure 45. A chlorophyll maximum with concentrations up to about 0.3 mg m-3 is observed at approximately 110m depth. The magnitude of this feature exhibits significant interannual variability, with a pronounced period of low chlorophyll concentration lasting from 1992-1998. Chlorophyll a concentrations at depths shallower than 50m display an annual cycle with winter maxima and summer minima.