Cooperative Institute for Research in Environmental Sciences

New ways of discretizing global climate models

Shan Sun (1,2) and Rainer Bleck (1,2,3)

(1) CIRES, (2) NOAA ESRL, (3) NASA GISS

A 3-dimensional global ocean circulation model, named iHYCOM, is under development at NOAA’s Earth System Research Laboratory. The model is destined to become the oceanic counterpart of the finite-volume, flow- following, icosahedral atmospheric model FIM (http://fim.noaa.gov). FIM uses an icosahedral horizontal grid and a hybrid-isentropic vertical coordinate.

Preliminary results from the ocean model alone and the coupled model will be discussed. Numerical merits of new ways of discretizing equations will be assessed by comparing iHYCOM and the standard HYCOM, both are forced with the same CORE forcings. Several performance measures indicate that running HYCOM on an icosahedral mesh is feasible. This paves the way for efficient coupling to an icosahedral atmospheric model without the need for an interpolating flux coupler.