The TRR 181 seminar is held by Dr. Hossein Kafiabad (The University of Edinburgh) on April 28, 11 am.

Grid-based calculation of Lagrangian mean

Abstract

Lagrangian averaging has been shown to be more effective than Eulerian mean in separating waves from slow dynamics in two-timescale flows. It also appears in many reduced models that capture the wave feedback on the slow flow. Its calculation, however, requires tracking particles in time, which imposes several difficulties in grid-based numerical simulations or estimation from fixed-point measurements. To circumvent these difficulties, we propose a grid-based method to calculate Lagrangian mean without tracking particles in time, which also reduces computation, memory footprint and communication between processors in parallelised numerical models. We also explore an application of this method in the context of shallow-water equations by quantifying the validity of wave-averaged geostrophic balance -- a modified form of geostrophic balance accounting for the effect of strong waves on slow dynamics.