Abstract

<jats:title>Abstract</jats:title>
<jats:p>Tidal currents, particularly in narrow channels, can be challenging to characterize due to high current speeds (&gt; 1 m s<jats:sup>−1</jats:sup>), strong spatial gradients, and relatively short synoptic windows. To assess tidal currents in Agate Pass, WA, we cross-evaluated data products from an array of acoustically-tracked underwater floats and from acoustic Doppler current profilers (ADCPs) in both station-keeping and drifting modes. While increasingly used in basin-scale science, underwater floats have seen limited use in coastal environments. This study presents the first application of a float array towards small-scale (&lt; 1 km), high resolution (&lt; 5 m) measurements of mean currents in energetic tidal channel and utilizes a new prototype float, the µFloat, designed specifically for sampling in dynamic coastal waters. We show that a float array (20 floats) can provide data with similar quality to ADCPs, with measurements of horizontal velocity differing by less than 10% of nominal velocity, except during periods of low flow (0.1 m s<jats:sup>−1</jats:sup>). Additionally, floats provided measurements of the three dimensional temperature field, demonstrating their unique ability to simultaneously resolve <jats:italic>in situ</jats:italic> properties that cannot be remotely observed.</jats:p>