Observations of Shoaling Internal Tides in Mamala Bay, HI

Shoaling internal tides in Mamala Bay, Hawaii were observed generating sudden drops in temperature and increases in salinity followed by turbulent fluctuations. Field work in the springs of 2010 and 2011 monitored currents, density, and turbulent kinetic energy (production and dissipation) in the presence of these events at 23m depth. The suite of instruments was tied into the University of Hawaii Kilo Nalu Nearshore Observatory for real-time data analysis. The shoaling "bores" were the main stratifying mechanism, cause of across shore near-bed flow, and significantly altered Reynolds shear stress profiles. During unstratified periods in which bores were not present, flow conditions and estimates of bottom roughness matched those found in the historical record for this site. During bore stratified periods, the estimates for bottom roughness were altered considerably. This is critical for understanding bottom roughness estimates in nearshore reef environments.