Building an idealised coupled system:

A quick update

Polly Smith, Amos Lawless, Alison Fowler*

School of Mathematical and Physical Sciences, University of Reading, UK

* funded by NERC

Objective

To use an idealised system to gain a greater theoretical understanding of the coupled atmosphere-ocean data assimilation problem:

• explore different approaches to coupled 4D-Var data assimilation using a single-column, coupled atmosphere-ocean model

Building the idealised systemTask 1: develop an idealised, single-column, coupled atmosphere-ocean model with a strong-constraint incremental 4D-Var assimilation scheme.

For this we need a model that

• is simple and quick to run• is able to represent realistic atmosphere-ocean coupling

Atmosphere:• simplified ECMWF single column model (SCM)

Ocean:• single column KPP (K-Profile Parameterisation) mixed-layer

ocean model

Update on progress so far· revisited stripped down SCM code, now includes simplified

version of IFS turbulent diffusion scheme· option to run with:

dynamics + turbulent diffusion only dynamics + full physics (i.e. original code)

· simplified turbulent diffusion scheme computes surface fluxes to pass to ocean model => ready to couple to ocean model

· (almost) ready to start writing adjoint models· continuing to produce & update documentation· svn repository now in place

ECMWF vdf only ECMWF full physics pjs vdf240oE, 19.89oS