ORCA1 configuration details are to be added to v3.3beta. ORCA1 is in use with several different vertical grids including a 75 level version which uses a double tanh function to set the vertical spacing. This same vertical grid is also used with some configurations of ORCA025. Support for ORCA1 will therefore be added in two stages:

1. The introduction of an optional double tanh function in domzgr. This will be selected via a logical (ldbletanh) set in each par*.h90 file. This will be false and the associated parameters set to "pp_do_not_use" for all configurations except for ORCA025 (key_orca_r025). In par_ORCA_R025.h90 two alternative sets are provided: one for 75 levels (with ldbletanh=T) and one for the standard 46 level case (with ldbletanh=F). The standard case will be used unless key_orca_r025=75 is defined.

2. The ORCA1 settings (par_ORCA_R1.h90) and associated changes will be added to the system with similar support for 75 and 46 level versions.

Support has been added for the use of key_dynldf_c3d with the ORCA1 configuration. This entails simple changes to ldfdyn_c3d.h90 and includes a generalisation of the vertical scaling coefficient from a function of jk to a function of depth so that it can be used with different numbers of vertical levels. The function (thanks to Ian Culverwell, UKMO) provides exactly the original values when using the standard 31 ORCA levels.

The allocation of ocean domains to ioserver processes is not done well in the default code when land-only regions are discarded (i.e. jpni*jpnj is not equal to jpnij). A development copy of the nemo_v3_3beta branch has been made (DEV_r2460_v3_3beta_NOL) which contains a suggested fix. This solution exchanges information via the layout.dat file and, therefore, requires a double start when starting with a new decomposition. The first attempt will create the layout.dat file and then exit gracefully. Subsequent submissions will run as normal and use the information in layout.dat to assign ocean processes to io servers based on their position in a virtual jpni by jpnj decomposition which does not discard land-only regions.