Rainer Bleck, LANL
The impact of numerical accuracy during vertical advection of T/S, which is part of the vertical regridding process in HYCOM, is investigated. The impact of several advection schemes on the vertical structure of the T/S field is quantified in terms of the amount of available potential energy generated during the regridding process. As expected, the piecewise linear method (PLM) used in HYCOM version 2.0 is found to substantially reduce vertical diffusion inherent in the piecewise constant or donor-cell method used in earlier versions of the HYCOM grid generator. A counterintuitive result of this study is that the piecewise parabolic method makes the regridding process more diffusive than does PLM.