1. February 2012 Milestone Materials Implicit coupling design document NUOPC Layer software prototype bundled with ESMF Updated NUOPC Layer reference manual Updated prototype examples under SVN, esmfcontrib Prototype atmosphere-ocean coupled applications:  NOGAPS-HYCOM – functional prototype, w/ concurrent exec.  COAMPS(-NCOM) – in progress  NEMS-GFS(-HYCOM) – in progress

2. Functions of prototype Extended the architecture in which major components (ATM, OCN, ICE, LND, WAV) are siblings to cases where coupling includes implicit dependencies. A single component instance can interact on multiple time scales. ( → No need to introduce multiple components) Use of Run() phases to access the component code for split time scales. A unified generic driver component applies to both implicit and explicit (and mixed) cases. Uses the same underlying data structure. The unified generic driver component supports sequential and concurrent execution of components.

3. Interoperability impact The implicit coupling problem is addressed by the same familiar data structures used for explicit coupling. Small, specific specialization routines promote clear separation of concerns. This makes code changes, e.g. switching from an explicit coupling problem to an implicit or semi-implicit problem, well defined. The generic implementation of the actual run sequence execution strictly follows ESMF and NUOPC rules. There should only be rare cases to override it. The NUOPC_RunSequence data structure holds the potential to support reverse execution. It may be possible to leverage this as a portable way to implement adjoints used in data assimilation.

4. More information See: http://www.earthsystemmodeling.org/plans/milestone_1105_nuopc.shtml For additional information on this milestone, including links to NUOPC Layer code, documentation, and supporting design documents.