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The generic NetCDF output routines nf_fwrite2d, nf_fwrite3d, and nf_fwrite4d routines were modified yesterday and included inside a module to allow optional arguments (see ​src:ticket:226). Since these routines are now inside an explicit interface, we need to follow the rules of pointer association for arrays passed as arguments. Notice that we follow such rules in other ROMS routines. I just missed such association in the IO routined modified by ​src:ticket:226. The three compilers that I tried pgf90, gfortran, and ifort 10.0 did not gave me errors.

However, Rosa Balbin tried using ifort 10.1 and got the error reported in the ​forum. We upgraded ifort to version 10.1 and were able to reproduce this error.

It is interesting how the other compiler relax such rules. The ifort folks treated this relaxation as a compiler bug which they corrected in version 10.1. I am personally sympathetic with strict compilers.

This is a big update for the incremental, strong constraint, 4DVar data assimilation algorithm (IS4DVAR). A new preconditioning conjugate gradient algorithm based on the Lanczos methodology is implemented. Two versions of the preconditioning are available:

• Spectral limited-memory preconditioner (Fisher, 1998)

• Ritz limited-memory preconditioning (Tshimanga et al., 2008)

Many thanks to Andy Moore for his help on implementing and testing the new algorithm.

Andy wrote a nice technical description and usage guidelines in ​wikiROMS for the new algorithm.

This the last stage of the upgrade for the IS4DVAR algorithm. The intermediate IS4DVAR driver Drivers/is4dvar_ocean.h and its associated conjugate gradient algorithm Utility/cgradient.h are removed and not longer supported. This algorithm computed incorrectly the background and observation cost functions when more that one outer loop is used (Nouter >1). This is corrected in the new algorithm.

From now on, only Drivers/is4dvar_lanczos_ocean.h and Utility/cgradient_lanczos.h will be supported and becomes the default IS4DVAR algorithm. No longer the option LANCZOS is needed to activate this algorithm. Several parameters and sections of code from the old driver are also removed for clarity and to avoid confusion.