An analysis, in temperature space, of the cross-shore heat flux by internal waves in shallow coastal water

Nonlinear internal waves, propagating toward the coast, transport significant amounts of energy and drive cross-shore water mass exchange and heat transport near the coast. Here we utilize field observations to quantify heat transport by nonlinear internal tides and high-frequency internal waves propagating to the coast in water depths ranging from 50 to 10 m. Data sets include extensive arrays of moored ADCPs and temperature, salinity and pressure sensors collected off of central California in 2017 and in Massachusetts Bay in 2008 and 2009. We analyze the cross-shore heat flux driven by internal waves in temperature space in order to diagnose water mass transformations and identify water temperature classes that significantly contribute to net cross-shore heat flux by internal waves. Heat flux by internal waves occurs at distinct temperature classes over time. This analysis distinguishes periodic fluxes from those that produce a net (wave-averaged) flux. For example, bottom water masses of the same temperature class are often advected back-and-forth by internal waves and do not contribute to a net heat flux. This method also demonstrates changes in temperature class of waters being transported cross-shore by internal waves. For example, the onshore flux of surface waters by internal waves tend to be at a lower temperature than the surface waters advected offshore.