Rainer Bleck and Shan Sun (NASA-GISS)
The recent IPCC call for century-scale climate forecasts has prompted
extensive experimentation with HYCOM coupled to the GISS atmospheric
circulation model. In the course of this work, the coupled model has
taught us a number of lessons about critical aspects of century-scale
earth system modeling. In this talk we share our experience with
particular focus on
(a) long-term conservation of properties conserved in the real system;
(b) net heat uptake/loss by the ocean and its sensitivity to numerical
vertical diffusion;
(c) the sensitivity of ENSO variability to near-surface vertical
resolution and the vertical extent of HYCOM's z coordinate
subdomain;
(d) efforts to tune the surface mixed layer to minimize trends in sea
ice coverage and to obtain a realistic SST in the equatorial cold
tongue;
(e) the fickleness of the meridional overturning circulation;
(f) ocean-atmosphere flux coupling issues.