Seasonal-to-Interannual Modulation of Fine-Scale Thermohaline Structure

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ABSTRACTOCE-0452574The goal of this studyl is sustained sampling of upper ocean hydrography to resolve the seasonal-to-interannual modulation of meso- and fine-scale thermohaline structure. Underwater gliders will be deployed to make repeated occupations of a 1300-km meridional section northward from Hawaii to 35 degrees N along 158degrees W. The observations will quantify the modulation of: (1) the horizontal density ratio in the mixed layer and upper thermocline, (2) spice variability in the thermocline, (3) horizontal variability in mixed-layer depth, (4) horizontal variability in the deep chlorophyll maximum, (5) depth-average velocity and vorticity. Using two Spray gliders deployed near the Hawaii Ocean Time-series (HOT) site off Hawaii, the section will be repeated on a roughly monthly basis. After making repeated sections for four months, the gliders will be recovered and freshly serviced glider will be redeployed. The gliders will carry sensors to measure temperature, salinity, depth, and fluorescence. Sampling characteristics of the relatively slow gliders will be assessed by comparison with data from a rapidly towed vehicle .Broader ImpactsThe fundamental goal of quantifying low-frequency modulation of fine-scale structure is relevant for climate dynamics concerns such as CLIVAR. The observations will address the problem of parameterizing "sub-grid-scale" processes in climate models. The glider sections will benefit from, and extend, the activities at the HOT site. Education and outreach activities include the training of a graduate student, the establishment of a web site, and dissemination of data. The graduate student will be involved in every aspect of the glider operation and data analysis. A web site will be developed with a purpose of making simple plots available to the public. The PIs will participate in community discussions on how to archive and distribute glider data to interested scientists.