Time-averaged and diagnostic fields in the 4D-Var algorithms

[arango]

The following time-averaged CPP options are now available:

• AVERAGES: use if writing out time-averaged nonlinear model fields.
• AD_AVERAGES: use if writing out time-averaged adjoint model fields. Used primarily in adjoint sensitivity simulations.
• RP_AVERAGES: use if writing out time-averaged representer model fields. Used only in the R4D-Var algorithm (W4DVAR) to save the representer model time-averaged fields for each outer loop in separated files.
• TL_AVERAGES: use if writing out time-averaged tangent linear model fields. It will used in future to load averages of the TLM kernel.

Notice that only one of these CPP options can be activated at the same time. They are mutually exclusive! This is because the same internal arrays (declared in mod_averages.F) are uses to stored the accumulated field sums.

Now, the I4D-Var and 4D-PSAS algorithms (IS4DVAR and W4DPSAS, respectively) will write out the time-averaged and diagnostic fields for each outer loop in separated files if the AVERAGES and/or DIAGNOSTICS_TS/DIAGNOSTICS_UV options are activated.

Many thanks to Andy Moore for suggesting this useful capabilities for the 4D-Var data assimilation algorithms. This will become handy in 4D-Var reanalysis of ocean circulation for a particular region.