Uncertainties in Internal Tide Generation and Energy Flux in the Tasman Sea

Macquarie Ridge, southwest of New Zealand, is a site of enhanced internal-tide generation, which produces a horizontal internal tide beam that propagates northwest across the Tasman Sea. This beam has been identified in satellite altimetry, gliders, and in situ measurements. Here, we use numerical models to estimate internal-tide generation and energy fluxes, and their associated uncertainties, at Macquarie Ridge. First, we compare realistic simulations from fully-nonlinear and quasi-linear models with in situ measurements to determine best estimates of internal tide generation and energy flux. Next, we use the quasi-linear model (CSW) to conduct numerous sensitivity experiments that quantify the uncertainties in internal-tide generation due to numerical approximations (e.g., grid resolution) and unknown environmental conditions (e.g., local stratification anomalies). Lastly, we use CSW, in conjunction with estimates of mesoscale currents and stratification, to quantify uncertainties in energy flux due to internal-tide interactions with mean flows at a range of time and length scales. These analyses provide context for analyzing observations and more sophisticated numerical simulations of the Tasman Sea.