id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
584	WARNING: major overault of ROMS kernel to complete nesting Phase III	arango	arango	"The ROMS algorithms were updated to include the final '''Phase III''' of nesting.  The nesting algorithms are now working for the idealized '''DOGBONE''' test case in composite and refinement grid configurations.

We get identical nesting solutions in serial with partitions, shared-memory ('''OpenMP'''), and distributed-memory ('''MPI''') for tile partitions of '''1x1''', '''2x2''', and '''3x3'''.  I have been debugging these algorithms since early January. It was quite tedious to get this working in all these computer configurations.

The development of '''Phase III''' was very difficult and I rewrote the main interface ('''nesting.F''') several times.  I was looking for an algorithm that it is easy to adjoint.  We plan to support adjoint-based algorithms (4D-Var) with nested grids in the future...

The ROMS nesting algorithms are very elegant but tricky. I assume that it will take sometime to the '''Users''' to master it.  We expect fine tuning of these algorithms in the future as we build more complex nesting applications.

The information for this release will be available in the [https://www.myroms.org/forum/viewtopic.php?f=13&t=2912 ROMS forum] shortly.

Good luck"	release	closed	major	Nesting/Composed Grids	Nonlinear	3.7	Done