id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
373	Level of no motion in 4DVar Balance Operator	arango	arango	"The error covariance balance operator was updated to include the options for what state variable to use as a constraints (in the off-diagonal terms), and a level of no motion option when computing the balanced free-surface contribution.

Notice that the following new parameters were added to input script '''External/s4dvar.in''':
{{{
! Balance operator level of no motion depth (m) used when computing balanced
! free-surface contribution, [1:Ngrids].

      LNM_depth == 1000.0d0               ! meters, positive

! Balance operator level of no motion flag used to compute balanced
! free-surface contribution:
!
!      [0] Integrate from local bottom to the surface
!      [1] Integrate from LNM_depth to surface or integrate from local bottom
!          if shallower than LNM_depth
!

      LNM_flag  =  0

! Balance operator logical switches for state variables to consider in the
! error covariance multivariate constraints.

balance(isSalt) =  T                      ! salinity
balance(isFsur) =  T                      ! free-sruface
balance(isVbar) =  F                      ! 2D momentum (ubar, vbar)
balance(isVvel) =  T                      ! 3D momentum (u, v)
}}}

I also cleaned few things:

 * Removed the internal flag '''SET_ZETA'''.  This is now the default configuration in all adjoint-based algorithm. This option was introduced a while ago during the perfect restart. The assignment of the free-surface to is its fast-time averaged value is now done by calling '''set_zeta''' in '''main3d''' and not in '''rhs3d'''.  This change was supported in the adjoint-based algorithms by activating this flag. This is fully tested and we get identical solutions.

 * Removed obsolete routine '''load_forcing''' from '''frc_adjust.F'''. This is not longer necessary.

 * Added a new global attribute '''state_vector''' to output NetCDF file containing the variables and their order in the 4DVar state vector."	upgrade	closed	major	Adjoint Based Algorithms	Adjoint	3.3	Done