TRR 181 Seminar "Reducing spurious diapycnal mixing in ocean circulation models."

The TRR 181 seminar is held byMargarita Smolentseva (AWI, PhD in M5) on December 6, 11 am at AWI (Am Handelshafen 12, Bremerhaven), building E, room E5100.

Abstract

Spurious diapycnal mixing of water masses occurs in ocean circulation models as an artefact appearing in the results of numerical algorithms application. Most of the models used in climate research are based on geopotential vertical coordinates, such as z- or generalised terrain following coordinates, which levels intersect isopycnals. This causes spurious diapycnal mixing during diffusion of a water-parcel by high-order upwind transport schemes. The growth of potential energy of the system appears without any sources which could cause it. This behavior is physically incorrect and leads to the energetic inconsistency. In order to reduced spurious dipycnal mixing, modified advective schemes with the dissipative part of the transport operators directed isopycnally were considered. Rediparametrisation (Redi 1982) was implemented in the ocean circulation model FESOM2.0 developed and used in AWI. Additionally, the choice of a high-order advection scheme can be essential for reducing artificial numerical spurious mixing. With the need to improve the accuracy of the standard 3rd/4th order vertex-centered advection schemes, they we compared them to two high-order transport algorithms. We also propose a finite-volume analog of the P1 finite-element advection scheme with consistent mass-matrix.