Performance Evaluation of Three Parameterizations on Internal Tidal Mixing in the Northern Pacific

Abstract

The accurate assessment of the energy dissipation of internal tides (ITs) is of great importance because ITs contribute significantly to abyssal mixing. Thus, in this study, the IT-driven dissipation and diapycnal diffusion in the northern Pacific are estimated using parameterizations proposed by St. Laurent et al. (2002), Koch-Larrouy et al. (2007), and de Lavergne et al. (2020) (hereafter referred to as LSJ02, KL07, and dL20, respectively). The performances of the three parameterizations are evaluated by comparing the calculated results with fine structure observations. In particular, the dissipation estimated by LSJ02 parameterization shows a bottom-intensified characteristic, with the patterns showing good agreement with the observations near seamounts. Moreover, 43% of the results calculated using the LSJ02 parameterization have errors lower than one order of magnitude in the generation sites of ITs. Meanwhile, the strongest dissipation estimated by the KL07 parameterization shifts to the thermocline, with the results showing the highest level of consistency with observations in the generation sites. The proportion of results with errors lower than one order of magnitude is 80.7%. Furthermore, the results calculated by dL20 parameterization agree well with the observations in the upper and middle layers, with the parameterization showing an accurate estimation of the remote dissipation. The percentages of the errors lower than one order of magnitude between the dL20 parameterization and observations account for 77.1% and 88.7% in the generation sites and far-field regions, respectively.