Seminar: Micro-rosette: a novel means of sampling for autonomous platforms

Ellen Briggs, PhD
Assistant Professor
Department of Ocean & Resources Engineering
University of Hawai’i at Mānoa

We have been developing a ‘micro-rosette’ for collecting water samples on mobile platforms such as profiling floats. Not all sensing technologies can measure at the rate required for mobile platforms so here we use this micro-rosette to collect and store samples to be measured at a later time. For Argo-style profiling floats, there is a ~9-day park cycle between profiles during which the sample analyses can be completed. The original aim was to measure DIC (dissolved inorganic carbon) through a method using a gas diffusion cell and C⁴D (capacitively coupled contactless conductivity detector) which requires sub-mL sample but analysis takes a couple hours to complete. Preliminary evaluation of the micro-rosette has been performed in a 5k L test tank and on a CTD/rosette down to 500 m depth off the coast of San Diego. Benchtop evaluation of the DIC measurement indicates precision of <0.2% RSD or + 4 µmol kg^-1 for samples <250 µL. Work is ongoing to integrate the micro-rosette onto a profiling float and to successfully deploy the DIC system in the field under elevated pressure. The micro-rosette may potentially open new opportunities for other analyses where sampling rate is the critical shortcoming, thereby expanding the capabilities of profiling floats to capture vertical profiles of other biogeochemical properties.

***Please join us ten minutes early for a virtual coffee hour hosted by Dr. Deniz Gedikli.***

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Meeting ID: 966 9616 0414
Passcode: 610418